INDEX []INDEX Sr. No. Article Name Author Page No 1 FAILURE MECHANISM OF 2DFRP COMPOSITE AND 3D...

INDEX

Sr.

No. Article Name Author

Page

No

1

FAILURE MECHANISM OF 2DFRP

COMPOSITE AND 3D FIBER POLYMERIC

COMPOSITE

Malikarjun M. Gurav 01

2 INVERTER FRIDGE Jyoti S. Jadhav 08

3 PRESERVATION OF THE COLD: THERMAL

INSULATION Prasad D. Kulkarni 14

4 THERMOELECTRIC REFRIGERATION Paresh M. Wadekar 17

5 SHAPE MEMORY ALLOY –SMART

MATERIAL Pravin U. Mane 20

6

RELIABILITY ANALYSIS AND LIFE CYCLE

COST OPTIMIZATION OF CNC TURNING

CENTER

Rajkumar B. Patil 24

7

EXPERIMENTAL METHOD TO CHECK

FLOW UNSTEADINESS AND PRESSURE

PULSATIONS IN A NUCLEAR REACTOR

COOLANT PUMP

Rahul R. Gaji 29

8 ADVANCED CAR TECHNOLOGIES BY 2020 Rajendra V. Pethkar

33

9

APPLICATION OF SURROGATE-COUPLED

EVOLUTIONARY COMPUTING TO ENHANCE CENTRIFUGAL-PUMP

PERFORMANCE

S. A. I. Bellari

35

10 DESIGN OF DIE SET FOR INNER LINK

PLATE OF STACKER CHAIN

Satish A. Mullya

39

11 NANO GENERATORS: WHAT, HOW AND

WHERE?

Sachin A. Urunkar

44

12 WATER TOWERS Sandip S. Chavan 50

13 KNOWLEDGE BASED ENGINEERING - IN

PRODUCT DEVELOPMENT Sumit V. Patil 51

14 HEAT TRANSFER ENHANCEMENT FROM

DISCRETE FINS Sujit V. Yadav 57

15 ULTRASONIC VIBRATIONS ASSISTED IN EDM

Vaibhav S. Ganachari 61

16 RAPID PROTOTYPING: INTRODUCTION Vinayak T. Kumbhar 65

17 TECHNIQUES OF COATINGS FOR CUTTING

TOOL Yuvraj P. Ballal 70

Vision of the Institute

To be a leader in producing professionally competent engineers

Mission of the Institute

We at ADCET, Ashta are committed to achieve our vision by

Imparting effective outcome based education

Preparing students through skill oriented courses to excel in their profession with

ethical values

Promoting research to benefit the society

Strengthening relationship with all stakeholders

Department Vision

To be a leader in developing mechanical engineering graduates with knowledge, skills &

ethics.

Department Mission

We, at the Department of Mechanical Engineering are committed to achieve our vision by,

M1- Imparting effective outcome based education.

M2- Preparing students to serve the society with professional skills and ethical values.

M3- Cultivating skills and attitude among students and faculties to promote research

Programme Educational Objectives (PEOs)

1. Provide solutions to the problems of mechanical and relevant engineering disciplines

using the knowledge of fundamental science and skills developed during graduation

studies.

2. Demonstrate an understanding about selected specific areas of mechanical

engineering in career development.

3. Communicate and function effectively using professional ethics, social and

environmental awareness.

4. Engage in lifelong learning, for effective adaptation to technological changes.

Program Outcomes (POs):

Students of Mechanical Engineering Graduates will be able to:

1. Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals, and an engineering specialization to the solution of complex engineering

problems.

2. Problem analysis: Identify, formulate, review research literature, and analyze complex

engineering problems reaching substantiated conclusions using first principles of mathematics, natural sciences, and engineering sciences.

3. Design/development of solutions: Design solutions for complex engineering problems

and design system components or processes that meet the specified needs with appropriate consideration for the public health and safety, and the cultural, societal, and environmental

considerations.

4. Conduct investigations of complex problems: Use research-based knowledge and

research methods including design of experiments, analysis and interpretation of data, and

synthesis of the information to provide valid conclusions.

5. Modern tool usage: Create, select, and apply appropriate techniques, resources, and

modern engineering and IT tools including prediction and modeling to complex engineering

activities with an understanding of the limitations.

6. The engineer and society: Demonstrate understanding of contemporary knowledge of

engineering to assess societal, health, safety, legal and cultural issues and the consequent

responsibilities.

7. Environment and sustainability: Understand the impact of the professional engineering solutions in societal and environmental contexts, and demonstrate the knowledge of, and

need for sustainable development.

8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and norms of the engineering practice.

9. Individual and team work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.

10. Communication: Communicate effectively on complex engineering activities, write

effective reports, make effective presentations, and give and receive clear instructions.

11. Project management and finance: Demonstrate knowledge and understanding of the

engineering and management principles and apply these to manage projects and in

multidisciplinary environments.

12. Life-long learning: Recognize the need for, and have the ability to engage in

independent and life-long learning in the broadest context of technological change.

PSO1. An ability to find out, articulate the local industrial problems and solve with the use

of mechanical engineering tools for realistic outcomes.

PSO2. An ability of collaborative learning to find out cost-effective, optimal solution for

social problems

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Department of Mechanical Engineer ing Page 1

1. FAILURE MECHANISM OF 2DFRP COMPOSITE AND 3D FIBER

POLYMERIC COMPOSITE

Malikarjun M. Gurav

Asst. Professor

INTRODUCTION

Composite materials are one of the widely used materials because they are lighter, stronger and

corrosion resistant. Composite materials have been designed to perform load bearing function by

providing desirable combination of high specific strength and specific stiffness. These desirable

properties can be achieved through different stacking sequences of lamina and through

manufacturing techniques.

2D FRP composite have fibers in two directions, that is, warp and weft fibers (Figure 1a).

Application of 2D FRP composites are restricted in many composites structures which are to be

designed to support transverse load. In addition, 2D FRP composites have low through-thickness

properties, high manufacturing cost, less delamination (that is, Separation of layers) and impact

resistant, low strain-to-failure and inter laminar fracture toughness and they are expensive in

thick laminate applications (Fredrik, 2009). To overcome this weakness of 2D FRP composites,

3D FRP composites are developed. The basic concept of 3D FRP composite is that, it has

reinforcement in the third direction also called warp weaver along with warp and weft fibers

(warp weaver binds the warp and weft fibers

Motivation for 3D FRP composite is that it has high delimitation resistance for applications

where significant shear is expected. Furthermore, not all application of composites are

necessarily thin shell type, so thicker laminates required laying up many layers which is

expensive and defect prone, that is, cost/quality issue. 3D FRP composite have great potential in

light weight aerospace structures and in industrial applications (Liyoung et al., 2002). But the

major roadblock in using 3D FRP composite material is the lack of suitable testing method and

standard to determine their mechanical properties.

The aim of this research work is to develop a reliable testing standard for compressive testing of

3D FRP composites. The specific aim of this research work is to check the feasibility of ASTM

standard D6641 for testing of 3D FRP composites. This research work explores the differences in

compression testing of 2D and 3D FRP composites through: a) Review of existing literature. b)

Performing experimental testing for both 2D and 3D FRP composites based on ASTM standard

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D6641 (compression through combined end and shear loading) and investigating the resulting

failure mechanism using SEM (Scanning Electron Micrograph). c) Simulating the ASTM D6441

test using Finite Element Analysis and analysing and comparing the failure stress state in the

specimens for both 2D and 3D FRP composites. Drawing conclusion about the suitability of

ASTM D6441 for its use with 3D fiber reinforced composites and making recommendations for

further work in this area.

In this literature, it is found that the compressive properties of 3D FRP composite is lower than

the 2D FRP composite (Brandt et al., 1996; Farley et al., 1992; Guess and Reedy, 1986), but 3D

FRP composite posses high strain to failure ratio as compared to 2D FRP composite, which

makes 3D FRP composite much more ductile material than 2D FRP composite This reduction in

the compressive properties is mostly because of the fibers crimping due weft yarn and warp

weaver.

Under compression load bearing yarn starts kinking, this is observed by (Cox et al., 1994 and

1992; Kuo and Ko, 2000). Kink band formation in 3D FRP composite is different from 2D FRP

composite, in 3D FRP composite, the kink band forms at the outer most surface yarn, where

crimping is excessive due to warp weaver. It is observed that two kink bands forms due to

pinching of surface yarn, when surface yarn breaks, its stiffness reduced but it prevents other

yarn from buckling. So, 3D FRP composite failed at different locations as compare to 2D FRP

composite where kink band forms in plane causing failure As 3D FRP composite failed at

different location by increasing load, so it possesses high strain to failure.

Up till now, a number of testing standards have been developed for the compression testing of

2D FRP composite, these standards have been used by various researchers and showed good

repeatability and agreements with the theoretical predictions. Different ASTM standards used for

compression testing of 2D FRP composite along with loading schemes are shown in Figure 3.

These standards however, cannot be used for 3D FRP composite because the same test may result

in a different internal stress state for 3D FRP composite as opposed to achieved stress state in 2D

FRP composite.

Different researchers have used available 2D FRP composite standards for 3D FRP composite,

but the results obtained through these test showed higher standard deviations coefficient of

variance. On the basis of literature surveys major findings in the development of 3D FRP

composite testing standards are:

i. In-homogeneity of local displacement field (Kuo et al., 2003);

ii. Different failure modes occurring simultaneously in 3D FRP composite (Callus et al., 1999);

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iii. Standard deviation (SD) and Coefficient of Variance (COV) variation in result data (Mahadik

et al., 2011; Gerlach et al., 2012);

iv. Existing specimen size, loading configurations and test methods being used do not provide

required failure stress state within the specimen (Harper et al., 1993; Seng, 1992);

v. Non availability of validated test methods for properties predictions.

The Standard whose feasibility for the testing of 3D FRP composite is considered as ASTM

D6641 (ASTM D6641), in this test method compressive stress is introduced into specimen

through combined end and shear loading. It is a well developed standard for testing of 2D FRP

composites (Unidirectional and Bidirectional composites); it is used to measure compressive

modulus, poison’s ratio, ultimate compressive strength, and ultimate compressive strain. In this

study, ASTM D6641 is used for testing of 3D FRP composite, in the same way it is used for 2D

FRP composite, that is, testing procedure, test setup, loading conditions, testing environment,

room temperature and load rate is same. Figure 4 shows ASTM D6641 test fixture, it consists of

four grips and two alignment rods. These grips also act as antibuckling guides, these guides

prevents the specimen from buckling and efficiently transfer entire load in the gage section.

In this test, compressive stress is introduced into the specimen through axial loading, which is

then transferred into the specimen in a form of shear load (along the specimen’s surface) and end

load (at specimen’s ends) through grips. Grips hold the specimen and apply shear load through

friction between grips and specimen. In order to apply uniform shear force on specimens surface,

the grips must be perfect smooth, because of low coefficient of friction of grips extra clamping

force is required which may damage the specimen between grips. So tabbed specimen along with

rough surface grips are used which required less clamping force and avoids damage of specimens

between grips. Tabbed specimens are used to avoid specimen crushing between guides and stress

concentration (Nisitan et al., 2003; Anthoine et al., 1998).

Materials used

Both specimens and tabs material for 2D FRP composite is bi-directional E-Glass plane weave.

For 3D FRP composite specimens are made with 3D fiber reinforced angle-interlocked E-Glass

woven composites and tabs are made with bi-directional E-Glass plane weave. The matrix used is

5052 (Araldite 5052 and Aradur 5052), which is an epoxy based system mixing ratio of

Araldite/Aradur used is 100/38 parts by weight.

Dimensions

Specimens and tab panels for 2D and 3D FRP composite are manufactured through vacuum

infusion technique to achieve uniformity and less void contents. After resin completely infused

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through the panels, it is left for curing for 15 h at 50°C. Specimen and tab dimensions for both

2D and 3D FRP composite are shown in Table 1 and Figure

Results

For comparison of compressive properties and internal failure mechanisms, both the 2D and 3D

FRP composite specimens are made with same dimension and tested according to the ASTM

D6641. Load rate used in testing is 0.5 mm/min and test is carried out at 18°C. Figure 7 shows

tested specimens along with the failure modes, all specimens failed in the gage section which is

an acceptable failure. Load deflection curve of 2D and 3D FRP composite tested

Table 2 shows experimental results of 2D and 3D FRP composite, In 3D FRP composite warp

and weft direction of yarns are very important, because in weft direction only weft yarns are

along the length where as in warp direction both warp yarn and warp weaver are along the length.

The compressive properties and internal failure is different in both directions, so 3D FRP

composite specimens are made in both directions. Table 2 shows that 2D FRP composite failed at

average failure load of 6004 N, and average compressive strength in the loading direction (S22)

is about 266 MPa. The results show that the compressive properties of 3D FRP composite are

less as compare to 2D FRP composite, this is due to fiber crimping caused by the warp weaver

and complex weave architecture. Table 2 shows that the compressive strength of specimens with

warp yarns along the length is 205 MPa which is more as compared to weft yarn along the length

having 176 MPa. This is because in warp direction both the warp weaver and warp yarn takes the

load, so the additional warp weaver in warp direction increases the compressive strength.

SCANNING ELECTRON MICROGRAPH (SEM) INVESTIGATION

In order to investigate internal failure mechanisms in 2D and 3D FRP composite, SEM is carried

out to enhance visual observation and to identify the internal failure mechanisms. For SEM

images, specimens’ desired location is coated with carbon layer to get clear image.

2D FRP composite

2D shows failure and delaminating (separation of layers) at top and bottom face of the specimen

also show magnified image of top and bottom face which identifies fiber micro buckling after

matrix cracking. Figure 9b shows fiber kinking a different location.

3D FRP composite

Both 3D FRP composite specimens are investigated, that is, warp yarn along the length and weft

yarn along the length.

3D FRP composite (warp yarn along length)

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Figure 10 shows failure in 3D FRP composite specimens with warp yarn along the length. In this

case, both warp weaver and warp yarn are along the length. As compared to 2D FRP composite,

there is no fiber micro buckling found at the top and bottom face due to influence of warp weaver

(Figure 10b). In 2D FRP composite delamination is found under compression but in 3D FRP

composite when failure starts, it is arrested by warp weaver and prevents further damage at that

location (Figure 10a). As in these specimens, both warp weaver and warp yarn are along the

length so they have higher compressive strength as compared to specimens which have only weft

warp yarn along specimen length.

3D FRP composite (weft yarn along length)

failure locations of specimens with weft yarns along the length. In this case, only weft yarns are

along the length, so compressive strength in this case is less. Figure 11a shows fibers kinking at

various location inside the specimen and fiber breaking at top and bottom surface due to the

influence of warp weaver. No Delamination is found in this case because; warp weaver binds the

layers together. Figure 11b shows kink band formation at different locations. The dominant

failure mode of 3D FRP composite in this arrangement is due to kinking at different location at

different loads.

Finite element analysis

ASTM D6441 test is simulated by using finite element analysis in ABAQUS to analyze and

compare the failure stress state of 2D and 3D FRP composite specimens. To achieve this, implicit

finite element analysis is carried out in ABAQUS based on homogeneous orthotropic laminate.

Homogeneous orthotropic laminate is considered because 2D FRP composite can be modeled as

laminate (ply’s stacking together to form laminate) whereas 3D FRP composite cannot be

modeled with ply’s due to influence of warp weaver, as it required approximation in order to

model it in a form of layer. After approximation properties of each layer can be calculated

through unit cell model, which is then used to calculate laminate properties, this is a very

extensive exercise and requires complete study. Failure stress state is investigated in the gage

section of the specimen that is along length, width and through thickness at macroscopic scale.

Load applied in the analysis is taken from experimental work (failure load) and effective material

properties are used.

Boundary conditions

Symmetry boundary conditions are applied in ABAQUS. Specimen along with tabs is modeled

with geometric symmetry in two planes, that is, Y-symmetry and Z-symmetry as shown in Figure

12. With this symmetry conditions quarter model is analyzed, which reduced the computational

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time. Each Y and Z symmetry condition has six degree of freedom three translational (U1, U2,

U3) and three rotational (UR1, UR2, UR3) along X, Y and z

Applied load

Compressive load is applied on the specimen according to the ASTM D6641 (ASTM D6641).

Load is applied on the un-tapered tab surface and at the end of specimen simultaneously (Figure

13). To simulate compressive load applied by the fixture grips on the specimen, a shear surface

traction is applied on untapered tab surface and end load is applied on the specimens end parallel

to the fixture grips. In finite element analysis in ABAQUS 2/3 of the load is transferred on the

un-tapered tab surface through shear surface traction and 1/3 of the load is transferred through

the end of the specimen (Seng, 1992; U.S. Department of Federal Aviation Administration,

2002). This end load and shear surface traction .

Element type

In this analysis, 3D solid elements C3DR are used. C3DR is an eight node brick element having

eight nodes in the corner. These elements perform linear interpolation in all three directions. For

comparison of 2D FRP composite with 3D FRP composite solid elements are used. In shell

element, the authors are ignoring through thickness properties by considering thickness is very

small, but here authors want to study the through thickness properties and stress variation.

Material properties

Constitutive material model for orthotropic materials used to calculate stress in finite element

analysis is given in Equations 1 and 2 (Mahmood, 2010). Nine independent material constants

are required to completely define the orthotropic material, that is, Modulus of elasticity

(E1, E2, E3), Modulus of rigidity (G12 ,G23, G1 ) and Poisson ratio (ν12, ν23, ν13 ). The material

properties used in the FE analysis for 2D and 3D FRP composite are given in Table 4.

Finite element results

Failure in 2D and 3D FRP composite is caused by the compressive stress S22 which is desired.

Investigation of stress variation at different locations in the gage section shows uniform stress

distribution and maximum compressive stress is found in the gage section. Stress concentration

effects are only present at tab tapper end as expected, and it does not contribute in specimen

failure. At some locations, mixed stress state (shear, tensile and compressive) is present due to

S11 (Stresses along x-direction) and S22 (Stresses along Y-direction) which is not significant.

The maximum compressive stress found in the gage section due to applied load is shown in Table

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5. This analysis is an exploratory analysis not a predictive analysis, just to see the internal stress

state due to applied load (Not predicting or validating the compressive strength).

Failure stress state in 2D FRP composite

The compressive stresses developed in the gage section due to applied load are around 256 MPa.

The maximum compressive stress developed in the specimen is 488 MPa which is due to stress

concentration, but it will not contribute in specimen failure (Figure 14a). Figure 14b shows stress

variation along length and width of the gage section. Stress paths are plotted at different locations

to see stress variation. Stress path plots at different location.

Failure stress state in 3D FRP composite

Compressive stresses developed in the gage section due to applied load are around 190 MPa. The

maximum compressive stress developed in the specimen is 344 MPa which is due to the stress

concentration, but it will not contribute in specimen failure (Figure 15a). Figure 15b shows stress

variation along length and width of the gage section.

Comparison of FE and experimental result

It comparison of experimental and finite element analysis results of 2D and 3D FRP composite.

The difference between FE and experimental results is less which is expected because effective

material properties are used and applied load is the failure load taken from experiments. The

compressive strength of 3D RFP composite obtained from FE analysis is an effective

compressive strength may not be true compressive strength because material properties used are

parallel to material axis but fabric used is angle interlocked where warp weaver is at an angle.

RESULTS AND DISCUSSION

Experimental results show that all specimens failed in acceptable failure Modes, that is, in the

gage section, which is according to ASTM D6641 standard, and average compressive strength of

3D FRP composite is less as compare to 2D FRP composite. 3D FRP composite are famous for

high strain to failure under compression loading, but load deflection curve do not show such

behavior. Standard deviation and co-efficient of variance for 3D FRP composite is high; this is

due to non uniform internal architecture and mixed failure modes.

SEM investigation shows that in 2D FRP composite, the major cause of failure is due to fiber

micro-buckling, fiber breaking and kink band formation, where as in 3D FRP composite the

major cause of failure is due to fiber breaking and kinking at various locations. Compressive

strength of 3D FRP composite is less as compare to 2D FRP composite; the main reason for this

reduction is fiber crimping caused by the warp weaver and complex weave architecture. In 3D

FRP composite compressive stresses in the warp direction is more because warp weaver and

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warp yarn both share the applied load, where as in weft direction only weft yarn takes the whole

load. This identifies that in case of 3D FRP composite compressive strength must be measured in

both warp and weft direction due to the influence of warp weaver. Failure theories show that

failure occurs in the gage section of the specimen which is desirable. But it does not give any

detail regarding failure mode and failure mechanisms. Based on experimental work, SEM

investigation and finite element analysis; it is clear that ASTM D6641 is not suitable for testing

of 3D FRP composite because SD and COV is high. Further load deflection curves do not show

high stain to failure as expected.

Future recommendations

Micro-mechanics model

In finite element model specimen is modeled with homogeneous orthotropic material which can

identify maximum stress location and stress variation pattern but it does not give any detail

regarding internal failure mechanisms. For this purpose micro mechanics model is required for

detailed FE analysis, it will also helpful in determining material properties of 3D FRP composite.

Advance failure theories for 3D FRP composite

More advanced failure theories such as LARC04 (Langely Research Center) can be applied to

predict failure in 3D FRP composites, because it includes fiber misalignment plane and kink

band angle to determine kink band formation in composites. This failure criterion can be

implemented in FE analysis which can effectively identify fiber and matrix failure along with

failure modes.

Modification in specimen size

Specimen size given in ASTM D6641 standard is not suitable for compression testing for 3D

FRP composite. Specimen size for 3D FRP composite requires modification as compared to 2D

FRP composite, because when the warp weaver is along the width of specimens then at least one

complete cycle of warp weaver must be present along the width of the specimen.

Properties determination for available material

There is a need to determine all material properties of available 3D FRP composite for detailed

FE analysis.

Validation of compressive strength with other standard

In this present work, ASTM D6641 is considered for determination of compressive strength of

3D FRP composite, for validation other compression testing standards such as D3410, D695 can

be used.

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REFERENCES

1. Anthoine O, Grandidie JC, Daridon L (1998). Pure Compression Testing Of Advanced

Fiber Composites. Compos. Sci. Technol. 58:735-740(6).

2. ASTM D6641, Standard test method for determining the compressive properties of

polymer matrix composites laminates using a combined loading compression (CLC) test

fixture.

3. Brandt J, Drechsler K, Arendts Fa-J (1996). Mechanical performance of composites

based on various three-dimensional woven fibre preforms. Comp. Sci. Tech. 56:381-382

4. Callus PJ, Mouritz AP, Bannister MK, Leong KH (1999). Tensile properties and failure

mechanisms of 3D woven GRP composites; Part A, 30:1277-1287

5. Cox BN, Dadhkak MS, Morris WL, Flintoff JG (1994). Failure mechanisms of 3D woven

composites in tension, compression and bending. Acta Metal. Mat. 42:3967-3984

6. Cox BN, Dadkhah MS, Inman RV, Morris WL, Zupon J (1992). Mechanisms of

compressive failure in 3D composites. Acta Metal. Mat. 40:3285-3298.

7. Farey GL, Smith BT, Maiden J (1992). Compression response of thick layer composite

laminates with through-the-thickness reinforcement. J. Rein. Plast Comp. 11:787-810

8. Fredrik S (2009). An Introduction to the Mechanics of 3D-Woven Fibre Reinforced

Composites. ISBN 978-91-7415-295-1.

9. Gerlach R, Clive R, Siviour CR, Petrinic N, Jens W (2012). In-plane and through-

thickness properties, failure modes, damage and delamination in 3D woven carbon fiber

composites subjected to impact loading. 72:397-411.

10. Guess TR, Reedy ED (1986). Additional comparisons of interlocked fabric and laminated

fabric Kevlar epoxy composites. J. Comp. Tech. Res. 8:163-168.

11. Harper JF, Miller NA, Yap SC (1993). Problems associated with the compression testing

of fibers reinforced plastics composites. 12:15-29.

12. Isaac MD, Jyi-iin L, Patrick MS (2008). Three dimensional characterization of textile

composites, Part B. 39:13-19.

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2. INVERTER FRIDGE

Jyoti S. Jadhav Asst. Professor

As we all know compressor is the basic thing that does the actual work in a refrigerator or

air conditioning unit. The amount of cooling simply depends upon the compressor. So by

controlling the compressor we can get the desired cooling effect. In most of the machines the

compressor is run by a motor. So one of the ways of controlling the temperature is to control the

motor which drives the compressor. I will mention one of them for comparison , In older times,

simple 'ON' 'OFF' control was used. In this method the compressor motor was either on or off

according to the preset temperature set point. There was no speed control of the motor. It ran

with full speed until the desired temperature is reached and then it switched off. Again it

switched on if temperature shoots above the setpoint.

This method is not very enticing and also lowers the life of the equipment due to frequent

on and off. In INVERTER COMPRESSOR method, the compressor motor is provided with a

speed control. So, it can change or regulate its speed depending upon the requirement eliminating

frequent 'on' and 'off'. Usually the speed control is employed by the use of variable frequency

technique in which the frequency of the current supplied to the motor is varied.

INVERTER COMPRESSOR

An inverter compressor is a compressor that is operated with an inverter. In the hermetic type, it

can either be a scroll or reciprocating compressor. This type of compressor uses a drive to control

the compressor motor speed to modulate cooling capacity. Capacity modulation is a way to

match cooling capacity to cooling demand to application requirements.

MARKET NEEDS FOR VARIABLE CAPACITY

Many refrigeration and air conditioning systems require reliable processes which are more

efficient, compact, environmental friendly, easy to install and to maintain. The cooling

requirements vary over a wide range during the day and over the year due to ambient conditions,

occupancy and use, lighting etc.

In comfort cooling, there may also be the need for a stable and accurate temperature and

humidity control in areas such as hospitals, IT & telecoms, process cooling. In applications

such as schools, restaurants and office buildings, it is important that the cooling system is

able to adapt to wide daily shifts in load.

In process applications such as fermentation, growing tunnels and industrial processes,

accurate temperature settings are required to secure production quality.

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DIFFERENT MODULATING TECHNOLOGIES

There are several ways to modulate the cooling capacity in refrigeration or air

conditioning and heating systems. The most common in air conditioning are: on-off cycling, hot

gas bypass, use or not of liquid injection, manifold configurations of multiple

compressors, mechanical modulation (also called digital) and inverter technology. Each have

advantages and drawbacks.

On-off cycling: results in switching off the fixed-speed compressor under light load

conditions and could lead to short cycling and the reduction in compressor lifetime.

Efficiency of the unit is reduced by pressure cycling and transient losses. The turndown

capacity is 100% or 0%

Hot gas pass: involves injecting a quantity of gas from discharge to the suction side. The

compressor will keep operating at the same speed but thanks to the bypass,

therefrigerant mass flow circulating with the system is reduced and thus the cooling capacity.

This naturally causes the compressor to run uselessly during the periods where the bypass is

operating. The turndown capacity varies between 0 and 100%.[1]

Manifold configurations: several compressors can be installed in the system to provide the

peak cooling capacity. Each compressor can run or not in order to stage the cooling capacity

of the unit. The turndown capacity is either 0/33/66 or 100% for a trio configuration and

either 0/50 or 100% for a tandem.[2]

Mechanically modulated compressor: this internal mechanical capacity modulation is based

on periodic compression process with a control valve, the 2 scroll set move apart stopping the

compression for a given time period. This method varies refrigerant flow by changing the

average time of compression, but not the actual speed of the motor. Despite an

excellent turndown ratio – from 10 to 100% of the cooling capacity, mechanically modulated

scrolls have high energy consumption as the motor continuously runs.

Inverter compressor: uses an external variable frequency drive - to control the speed of the

compressor. The refrigerant flow rate is changed by the change in the speed of compressor.

The turndown ratio depends on the system configuration and manufacturer. It modulates

from 15 or 25% up to 100% at full capacity with a single inverter from 12 to 100% with a

hybrid tandem.

WORKING PRINCIPLE

The variable frequency drive controls the speed of compressor motor. The compressor is

specifically designed to run at different motor speeds to modulate cooling output. Variable speed

operation requires an appropriate compressor for full speed operation and a special compressor

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lubrication system. Proper oil management is a critical requirement to ensure compressor

lifetime. Proper oil management provides proper lubrication for scroll set at low speed and

prevents excess oil from being injected into the circuit when operating at full speed

APPLICATIONS

Variable speed technology can be implemented in HVACR, close control and process cooling

applications and as diverse as packaged or split air-conditioning units, rooftops,chillers, precision

cooling, VRF and condensing units.

Rooftop: is a very common unit type. The rising cost of energy means that air conditioning

manufacturers must develop new generation of high-efficiency, cost-effective air

conditioners for commercial buildings that meet or exceed a part-load efficiency standard of

typically 18 IEER. The aim is to reduce energy use by 30% over current equipment. Inverter

technology helps OEMs to build units which meet this demand.

Air handling units with integrated cooling are used in commercial applications for air

conditioning and humidity control in diverse ranges of buildings such as small office

buildings, fitness and medical centres. Inverter compressor solutions enable smooth

modulation and huge energy savings.

Modular chillers: a typical modular chiller installation uses multiple fixed-speed. These units

share the same water system to supply the building with cooled or heated water. Hybrid

tandem, associating one inverter and one fixed-speed compressor, can better match the

capacity requirement compared to a modular chiller with fixed-speed tandem compressors

and increases efficiency.

Close control units are used in the cooling of IT and electronic equipment used in data

centres, telecommunications and in manufacturing industries. Power management, energy

consumption and heat loads are major challenges. Maintenance of a stable temperature and

humidity control, compactness of the system and overall efficiency are key design challenges

in these applications for ensuring data safety and availability. This is where inverter

technology makes the difference.

Process cooling In many industries the machinery and processes generate a large amount of

heat which requires cooling, to protect the equipment and / or to ensure that the product

being manufactured is of the required quality. Inverter technology helps to secure the process

while providing greater efficiency.

VRF - Variable Refrigerant Flow VRF units are very popular cooling or reversible

systems (heating and cooling). They combine flexibility for building owners and occupants alike,

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with energy efficiency, high comfort, and ease of installation, without compromising on

reliability. VRF systems already extensively use inverter technology.

REFERENCES

1. http://www.pipelineandgasjournal.com/bypass-method-recip-compressor-capacity-

control

2. http://www.ishrae.in/journals/2000apr/article02.html

3. http://info.aia.org/aiarchitect/thisweek09/0410/0410p_vrf.cfm

http://www.pipelineandgasjournal.com/bypass-method-recip-compressor-capacity-

http://www.ishrae.in/journals/2000apr/article02.html

http://info.aia.org/aiarchitect/thisweek09/0410/0410p_vrf.cfm

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3. PRESERVATION OF THE COLD: THERMAL INSULATION

Prasad D. Kulkarni

Associate Professor

Cryogenic insulation system development began during the period 1877 to 1908,

coinciding with the first liquefaction of key industrial gases. D'Arsonval first demonstrated the

vacuum flask in 1887 [1]. This design was significantly improved by Dewar in 1893 by silvering

the walls of the flask. The concept of filling the vacuum space with powder was illustrated by

Stanley in 1912 [2]. This work led to the development of vacuum flasks (dewars) for the

preservation of cryogens, milk, hot or cold beverages, etc. and later for the preservation of

biological matter for a wide range of farming and medical purposes. From the discovery of

superconductivity in 1911 to its widespread proliferation by 1961, no significant advancements

in superconducting applications were made during this nearly 50-year period. The lull can be

attributed in part due to refrigeration processes that were difficult and inefficient, as well as, the

lack of high-efficiency insulated storage vessels. With the advent of the Cold War after World

War II, especially the beginning of the US space program in the 1960's, there was an explosion in

activity with the development of hydrogen and other liquefiers, advancements in high

performance thermal insulation systems and new cryogenic tank and vacuum piping designs [3].

An early vacuum-jacketed cryogenic tank insulation system design of multiple radiation shields,

shown in FIGURE 2, was advanced by Cornell in 1947 [4]. Multilayer' insulation (MLn, which

could provide at least an order of magnitude of improvement in the performance as compared to

evacuated perlite, was first demonstrated by Peterson in 1951 [5]. MLI systems were well

developed by about 1960 through the work of Matsch, Kropschot, Hnilicka, and others [6,7,8].

Later innovations improving the performance of dewars included vapor shield cooling, neck tube

cooling and low heat leak supports [9].

Of course, there were other supporting technologies that enabled thermal insulation

systems for superconducting applications, such as the process of welding of stainless steel (e.g.,

[9]) and the accidental invention of Teflon [10]. Key innovations in welding were brought about

through World War II [11]. Scott's original textbook on cryogenic engineering devotes many

pages on "insulation" and most of these involve the discussion of obtaining high vacuum

including the use of Teflon; however MLI is never mentioned [12]. These technologies

culminated in the production of large size vacuum-jacketed tanks (~50,000 liters liquid nitrogen

or liquid hydrogen), high vacuum levels with longer retention life and low heat flux insulation

systems (i.e., 10 to 100 times lower than evacuated perlite). Although the majority of the work

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after WWII was focused on liquid hydrogen production and storage, the areas of

superconductivity and liquid helium were direct beneficiaries. It is important to note that the

Collins liquefier was invented and developed during the same timeframe.

FIGURE 2. Early cryogenic tank design with multiple radiation shields from U.S. Patent 2,643,022 (left) and later

MLI system concept from U.S. Patent 3,007,596 (right).

This simpler refrigeration technology together with the new high efficiency cryogen storage

technology enabled the explosion in liquid helium experimentation and research in

superconducting applications. Worldwide, the number of labs with liquid helium capability grew

from only 15 in 1946 to more than 200 by 1960 [13]. The cryogenic tank technology has

improved over the years from storing a cryogen for a few hours to many months. The storage life

of cryogens extends to years for space probes thus demonstrating the technology has made

improvements by many orders of magnitude.

REFERENCES

[1] Almqvist, Ebbe, History ofIndustrial Gases, Kluwer Academic I Plenum Publishers, New

York, 2003, pp. 170-178.

[2] Stanley, W., Heat-insulated receptacle, US Patent No. 1,071,817, 1912. Sloop, John L.,

Liquid Hydrogen as a Propulsion Fuel. 1941 to 1959, NASA SP-4404 (1978).

[3] Cornell, W.D., "Radiation shield supports in vacuum insulated containers," US Patent

2,643,022(1947).

[4] Peterson, P., "The heat-tight vessel," University of Lund, Lund, Sweden (1951).

[5] Matsch, L.C., "Thermal insulation," US Patent No. 3,007,596(1956).

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[6] Kropschot, R.H., et aI, "Multiple-layer insulation," in Advances in Cryogenic Engineering

5, American Institute of Physics, New York, 1960, pp. 189-197.

[7] Hnilicka, M.P., "Engineering aspects of heat transfer in multilayer reflective insulation

and performance of NRC insulation," in Advances in Cryogenic Engineering. 5,

American Institute of Physics, New York, 1960, pp: 199-208.

[8] Scurlock, Ralph G., Low Loss Storage and Handling ofCryogenic LiqUids: The

Application of Cryogenic Fluid Dynamics, Kryos Publications (2006).

[9] Anon., "Scientist sees rustless iron, stainless steel," The Southeast Missourian, September

12, 1929.

[10] Funderburg, Anne Cooper, "Making Teflon Stick," Invention and Technology

magazine, summer 2000.

[11] Smith, Patricia L., "Welding and WW n," Welding Design and Fabrication, June

1,2005.

[12] Scott, Russel B., Cryogenic Engineering, National Bureau of Standards for the Atomic

Energy Commission, pp. 142-214.

[13] Thevenot, Roger, A History ofRefrigeration throughout the World, International

Institute of Refrigeration, Paris, 1979, pp. 272-291.

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4. THERMOELECTRIC REFRIGERATION

Paresh M. Wadekar

Asst. Professor

Refrigeration means removal of heat from a substance or space in order to bring it to a

temperature lower than those of the natural surroundings. In this context, Thermoelectric

Refrigeration aims at providing cooling effect by using thermoelectric effects rather than the

more prevalent conventional methods like those using the ‘vapour compression cycle’ or the ‘gas

compression cycle’.

There are 5 thermoelectric effects and these are observed when a current is passed

through a thermocouple whose junctions are at different temperatures. These phenomenon are the

Seeback effect, the Peltier effect, the Joulean effect, the conduction effect, and the Thomson

effect. Thermoelectric cooling, also called "Peltier Effect", is a solid-state method of heat transfer

through dissimilar semiconductor materials. It is based on the thermoelectric effect known as

‘Peltier Effect‘ according to which if current is passed through a thermocouple, then the heat is

absorbed at one junction of the thermocouple and liberated at the other junction. So by using the

cold junction of the thermocouple as the evaporator, a heat sink as the condenser and a DC power

source as the compressor of the refrigerator, cooling effect can provided.

Thermoelectric Coolers are solid state devices without moving parts, fluids or gasses. The

basic laws of thermodynamics apply to these devices just as they do to conventional heat pumps,

absorption refrigerators and other devices involving the transfer of heat energy. However, the

construction and structural details of a TE module are quite different from normal refrigerators

and requires a knowledge of materials and semiconductor technology in addition to heat transfer.

Therefore, selection of the proper TE Cooler for a specific application requires a valuation of the

total system in which the cooler will be used. In a TE, energy may be transferred to or from the

thermoelectric system by three basic modes: conduction, convection, and radiation. Comparison

and evaluation of various refrigeration systems requires a parameter which is applicable for all

refrigerating machines. The performance of cooling machines is therefore expressed in terms of a

non-dimensionless parameter called the Coefficient of Performance (C.O.P.) which is expressed

as the ratio of useful effect to work input. There is ease of interchanging the cooling and heating

functions by reversing the direction of current in the thermocouple. Thermoelectric systems are

vibration less and have no moving parts. Hence there is no problem of wear and noise. There is

no problem of containment and pollution because no refrigerant or chemical is used. Since there

is no bulky equipment it provides ease of miniaturization for small capacity systems. The

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capacity can be controlled easily by varying the current and hence the amount of heat absorbed or

evolved at the junctions. The system is highly reliable (with a life of > 250,000 hours). This

system also has the capacity to operate under various values of gravity (including zero gravity)

and in any position.

DETAILS OF THERMOELECTRIC MODULE

In practical use, couples are combined in a module where they are connected electrically

in series, and thermally in parallel. Normally a module is the smallest component commercially

available. Modules are available in a great variety of sizes, shapes, operating currents, operating

voltages and ranges of heat pumping capacity. The present trend, however, is toward a larger

number of couples operating at lower currents. The user can select the quantity, size or capacity

of the module to fit the exact requirement without paying for excess power.

Fig. Thermoelectric module principle

Fig. Thermoelectric Module

In a typical domestic refrigerator, a cooling power of about 50 watt is needed. The thermo

elements are connected by flat strips of a good electrical conductor, e.g. copper or aluminum, so

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as to form a rectangular array. If the spaces between the elements are large they should be filled

with a good thermal insulator, but if they are small this is unnecessary. The faces of the metal

connectors are ground flat and are pressed against the flat surfaces of two large metal slabs to

which fins are attached. It is important that the slabs should be electrically insulated from the

metal connecting strips but the thermal contact must be good. These metal slabs are drawn

together by bolts arranged round their periphery.

Specification of Thermoelectric module

BIBLIOGRAPHY

1. A. K. Pramanick and P. K. Das , "Constructal design of a thermoelectric device,"

Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur.

2. B. J. Huang, C. J. Chin and C. L. Duang , "A design method of thermoelectric cooler,"

Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan.

3. Development of a heat exchanger for the cold side of a thermoelectric module

J.G. Via´n *, D. Astrain Department of Mechanical Engineering, Universidad Pu´

blica de Navarra, UPNA, 31006 Pamplona, Spain

4. D. Zhao and G. Tan, "A review of thermoelectric cooling: Materials, modeling and

applications," Applied Thermal Engineering, vol. 66, no. 1–2, pp. 15-24, May 2014.

5. M. K. Rawat, H. Chattopadhyay and S. Neogi, "A review on developments of

thermoelectric refrigeration and air conditioning systems: a novel potential green

refrigeration and air conditioning technology," International Journal of Emerging

Technology and Advanced Engineering, vol. 3, no. 3, pp. 362-367, Feb 2013.

6. Performance Prediction and Irreversibility Analysis of a Thermoelectric Refrigerator with

Finned Heat Exchanger F. Meng, L. Chen¤ and F. Sun college of Naval Architecture

and Power, Naval University of Engineering, Wuhan 430033, P.R. China.

OPERATING VOLTAGE 12 VDC

CURRENT MAX 6 AMP

VOLTAGE MAX 15.2 VDC

POWER MAX 92.4 VDC

POWER NOMINAL 60 WATTS

DIMENSIONS 40mm*40mm*3.6mm

CABLE LENGTH 100-300mm

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5. SHAPE MEMORY ALLOY –SMART MATERIAL

Pravin U. Mane

Asst. Professor

The technology push, towards ‘smart’ systems with adaptive And or intelligent functions and

features, necessitates the increased use of sensors, actuators and micro-controllers; thereby

resulting in an undesirable increase in weight and volume of the associated machine components.

The development of high ‘functional density’ and ‘smart’ applications must overcome technical

and commercial restrictions, such as available space, operating environment, response time and

allowable cost. In particular, for automotive construction and design: increased mass directly

results in increased fuel consumption, and automotive suppliers are highly cost-constrained.

Research on the application of smart technologies must concentrate on ensuring that these

‘smart’ systems are compatible with the automotive environment and existing technologies. The

integration and miniaturization of integrated micro controllers and advanced software has

enabled considerable progress in the field of automotive sensors and control electronics.

However, the technical progress for automotive actuators is relatively poorly advanced.

Currently, there are about 200 actuation tasks are performed on vehicles with conventional

electro-magnetic motors, which are potentially sub-optimal for weight, volume and reliability.

Shape memory alloy (SMA) or ‘‘smart alloy’’ was first discovered

by Arne Oleander in 1932 and the term ‘‘shape-memory’’ was first described by Vernon in 1941

for his polymeric dental material. The importance of shape memory materials (SMMs) was not

recognized until William Buehler and Frederick Wang revealed the shape memory effect (SME)

in a nickel-titanium (NiTi) alloy in 1962, which is also known as NiTinol (derived from the

material composition and the place of discovery, i.e. a combination of NiTi and Naval Ordnance

Laboratory). Since then, the demand for SMAs for engineering and technical applications has

been increasing in numerous commercial fields; such as in consumer products and industrial

applications, structures and composites, automotive, aerospace, mini actuators and micro-

electromechanical systems (MEMS), Robotics, biomedical and even in fashion. Although iron-

based and copper-based SMAs, such as Fe– Mn–Si, Cu–Zn–Al and Cu–Al–Ni, are low-cost and

commercially

Available, due to their instability, impracticability (e.g. brittleness)

and poor thermo-mechanic performance; NiTi-based SMAs are much more preferable for most

applications. However, each material has their own advantage for particular requirements or

applications. In this work, a brief summary of SMA, its design feasibility and the variety of SMA

applications are compiled and presented. SMA applications are divided into several sections

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based on the application domain, such as automotive, aerospace, robotics and biomedical, as well

in other areas. Most of the work presented here has an emphasis on NiTi SMAs, but other forms

or types of smart materials such as high temperature shape memory alloys (HTSMAs), magnetic

shape memory alloys (MSMAs), SMM thin film (e.g. NiTi thin film) and shape memory

polymers (SMPs) are also discussed. However, intensive topics such as metallurgy,

thermodynamics and mechanics of materials will not be addressed in detail.

2. Shape memory alloy overview:

SMAs are a group of metallic alloys that can return to their original form (shape or size) when

subjected to a memorization process between two transformation phases, which is temperature or

magnetic field dependent. This transformation phenomenon is known as the shape memory effect

(SME). The basic application of these materials is quite simple, where the material can be readily

deformed by applying an external force, and will contract or recover to its original form when

heated beyond a certain temperature either by external or internal heating (Joule heating); or

other relevant stimuli such as a magnetic field for MSMAs.

2.1. Shape memory effect and Pseudo elasticity

Practically, SMAs can exist in two different phases with three different crystal structures (i.e.

twinned martensite, detwinned martensite and austenite) and six possible transformations. The

austenite structure is stable at high temperature, and the martensite structure is stable at lower

temperatures. When a SMA is heated, it begins to transform from martensite into the austenite

phase. The austenite-start-temperature (As) is the temperature where this transformation starts

and the austenite-finish-temperature (Af) is the temperature where this transformation is

complete. Once a SMA is heated beyond As it begins to contract and transform into the austenite

structure, i.e. to recover into its original form. This transformation is possible even under high

applied loads, and therefore, results in high actuation energy densities. During the cooling

process, the transformation starts to revert to the martensite at martensite start- temperature (Ms)

and is complete when it reaches the Martensite finish-temperature (Mf). The highest temperature

at which martensite can no longer be stress induced is called Md and above this temperature the

SMA is permanently deformed like any ordinary metallic material. These shape change effects,

which are known as the SME and pseudoelasticity (or superelasticity), can be categorised into

three shape memory characteristics as follows:

(1) One-way shape memory effect (OWSME):

The one-way SMA (OWSMA) retains a deformed state after the removal of an external force,

and then recovers to its original shape upon heating.

(2) Two-way shape memory effect (TWSME) or reversible SME:

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In addition to the one-way effect, a two-way SMA (TWSMA) can remember its shape at both

high and low temperatures. However, TWSMA is less applied commercially due to the ‘training’

requirements and to the fact that it usually produces about half of the recovery strain provided by

OWSMA for the same material and it strain tends to deteriorate quickly, especially at high

temperatures. Therefore, OWSMA provides more reliable. Various training methods have been

proposed, and two of them are: Spontaneous and external load-assisted induction.

(3) Pseudoelasticity (PE) or Superelasticity (SE):

The SMA reverts to its original shape after applying mechanical loading at temperatures between

Af and Md, without the need for any thermal activation. In addition to the ‘material TWSME’

above, a biased OWSMA actuator could also act as a ‘mechanical TWSME’ at a macroscopic

(structural) level; which is more powerful, reliable and is widely implemented in many

engineering applications. The SME is a diffusionless solid phase transition between martensitic

and austenitic crystal structures There are other transformations associated with shape memory

such as rhombohedral (R-phase), bainite and the ‘rubberlike behaviour’ (RLB) in martensite

stage ,which are not discussedin detail, in this work.Hysteresis is a measure of the difference in

the transition temperatures between heating and cooling (i.e. DT = Af _ Ms), which is generally

defined between the temperatures at which the material is in 50% transformed to austenite upon

heating and in 50% transformed to martensite upon cooling .This property is important and

requires careful consideration during SMA material selection for targeted technical applications;

e.g. a small hysteresis is required for fast actuation applications (such as MEMSs and robotics),

larger hysteresis is required to retain the predefined shape within a large temperature range (such

as in deployable structures and pipe joining) .In addition, the transition temperatures referred to

identify the operating range of an application. These transition temperatures and the hysteresis

loop behaviour are influenced by the composition of SMA material, the thermomechanical

processing tailored to the SMA and the working environment of the application itself (e.g.

applied stress) . These transition temperatures can be directly measured with various techniques

such as differential scanning calorimetry (DSC), dilatometry, electrical resistivity measurement

as a function of temperature, and can be indirectly determined from a series of constant stress

thermal cycling experiments. Some of the SMAs physical and mechanical properties also vary

between these two phases such as Young’s modulus, electrical resistivity, thermal conductivity

and thermal expansion coefficient. The austenite structure is relatively hard and has a much

higher Young’s modulus; whereas the martensite structure is softer and more malleable; i.e. can

be readily deformed by application of an external force . When an external stress is applied

below the martensite yield strength (approximately 8.5% strain for NiTi alloys and 4–5% for

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copper-based alloys ), the SMA deforms elastically with recoverable strain. However, a large

non-elastic deformation (permanent plastic deformation) will result beyond this point. Most

applications will restrict the strain level; e.g. to 4% or less, for NiTi alloys.

Recent developments

In the 1990’s, the term shape memory technology (SMT) was introduced into the SMM

community .SMA application design has changed in many ways since then and has found

commercial application in a broad range of industries including automotive, aerospace, robotics

and biomedical. Currently, SMA actuators have been successfully applied in low frequency

vibration and actuation applications. Therefore, much systematic and intensive research work is

still needed to enhance the performance of SMAs, especially to increase their bandwidth, fatigue

life and stability. Recently, many researchers have taken an experimental approach to enhance

the attributes of SMAs, by improving the material compositions (quantifying the SMA phase

transition temperature to achieve a wider operating temperature range, and better material

stability, as well as to improve the material response and stroke with better mechanical design (or

approach), controller systems and fabrication processes. Research into alternative SMMs, forms

or shapes, such as MSMA, HTSMA, SMP, shape memory ceramic, SMM thin film or a

combination of them (i.e. hybrid or composite SMMs), are also intensively being conducted, and

the number of commercial applications is growing each year.

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6. RELIABILITY ANALYSIS AND LIFE CYCLE COST OPTIMIZATION OF

CNC TURNING CENTER

Rajkumar B. Patil

Asst. Professor

1. Introduction

In today's competitive marketplace, the reliability of a product/system is becoming

increasingly more important [1]. The informed customers not only weigh the ability of the

product to meet their requirements, and the purchase price of the product, but also the costs that

will be incurred to maintain the function of the product over its life time [2]. Hence, lowering the

life cycle cost of a product will increase its value and attractiveness to the customer. Reliability

and maintainability greatly influence the life cycle cost of complex systems [3]. Reliability

analysis helps to manage the product/ system failures while life cycle cost (LCC) analysis deals

with the cost implications over the operational life of the system. Reliability and LCC can have

implications in terms of risk, safety, profit margins, cost of maintenance and operations etc [4].

The life cycle costs can be categorized as acquisition costs and sustaining costs. The acquisition

cost is the easily identifiable element in the life cycle of any system. But, to estimate the

sustaining costs, it is required to apply reliability and maintainability (R&M) principles. R&M

technology helps to predict failures and cost of failures. The mean time between failures (MTBF)

and the mean time to repair (MTTR) are important parameters from R&M theory that impact

LCC.

During the last four decade, most of the mechanical systems have become complex and

are incorporated with electrical, electronics and software systems. Reliability analysis of such

systems is essential in order to satisfy customers, failure free operations, minimizing LCC etc.

Computerized numerical control (CNC) turning centers have increasingly been introduced into

sophisticated mechanical machining processes [5]. As a result of their considerable inherent

flexibility, stable machining accuracy and high productivity, CNC turning centres are of immense

interest to the users. However, as the breakdown of a single CNC machining centre may result in

the production of an entire workshop being halted and repairs are more difficult and expensive

when a breakdown occurs, CNC machining centre are capable of creating lot of troubles to the

users [6]. In the meantime, the manufacturers are also required to improve continuously the

reliability of CNC turning centre to sharpen their competitive edge in the marketplace. So the

reliability of CNC turning centre has an increased significance and paramount importance both to

the manufacturers and the users.Keeping in this view, it is proposed to carry out reliability and

LCC analysis of CNC turning center. The main objectives of the case study in this paper are:

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To understand the nature of failure patterns of the CNC turning center;

To estimate the reliability characteristics of the selected machine based on the assessment

of trends in maintenance data;

To estimate the LCC of CNC turning center;

To identify the critical components of the CNC turning center, which require further

improvement through effective maintenance policy to enhance reliability; and

Further the emphasis is on to optimize the LCC of CNC turning center.

2. Literature Review

The reliability engineering discipline has undergone evolutionary growth and

advancements during the last six to eight decades; especially after world war II. As a result

many studies have been reported in the published literature. In this section, some of the reliability

studies conducted over the years have been revisited, highlighting the applications and

methodologies used.Reliability centered maintenance (RCM) is a method for maintenance

planning developed within the aircraft industry and later adapted to several other industries and

military branches. Rausand [7] presented a structured approach to RCM, and discussed the

various steps in the approach. It is found that, RCM policy is better policy than age related

maintenance policy [8].A procedure for the evaluation and selection of rolling contact bearings

for an application from reliability point of view is suggested by Sehgal et al., [9] which is based

on graph theory and matrix method. Proposed procedure can also compare two or more bearings

based on coefficient of similarity/ dissimilarity. Barabady and Kumar [10] evaluated reliability

characteristics of crushing plant number 3 at Jajarm Bauxite Mine in Iran. The test statistics U, χ2

distribution has been used for trend test and correlation and K-S test (goodness of fit) for best fit

distribution. Conveyor subsystem and screen subsystem are found to be critical from a reliability

point of view.Zio [1] discussed some critical issues in the field of reliability and safety in his

paperreliability engineering: old problems and new challenges’;especially in case of complex

system. Modern systems have four basic components: hardware, software, organizational and

human.Louit et al., [11] reviews several tests available to assess the existence of trends and

presented a framework for model selection to represent the failure process for a component or

system. The model selection framework is directed towards the discrimination between the use of

statistical distributions to represent the time to failure (renewal approach); and the use of

stochastic point process (repairable system approach), when there may be the presence of system

ageing or reliability growth.Castet and Saleh [12] conducted a nonparametric analysis of satellite

reliability for 1584 Earth-orbiting satellites launched between January 1990 and October 2008.

The results of this analysis are useful for space industry for redesigning subsystems, screen

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programs etc.Lad and Kulkarni [13] estimated reliability of machine tool in absence of field

failure data. It uses the knowledge and experience of maintenance personnel to obtain the

parameters of lifetime distribution of the repairable and non-repairable components/ assemblies.

This technique is useful for designers to use reliability based approaches to design more reliable

machine.Decision making processes are critical for organizations within a scenario of intense

competitiveness. Godoy et al. [14] focused on condition managed critical spares (CMS) and

presented a technique to enhance spare parts ordering decision making when companies need to

ensure a reliability threshold restricted by lead time. Reliability centered maintenance data can

also be used for spare part control [15]. Reliability of the system can be improved through

preventive maintenance schedule. Chen [16] applied genetic algorithm method for deciding

preventive maintenance schedule of reusable rocket engine (RRE). Furthermore, Wolde [17]

presented a case study of optimizing inspection intervals for railway carriers in order to minimize

cost of maintenance.Barabadi et al. [18] considered different factors such as the operational

environment, maintenance policy, operator skills, etc. for spare part provision studies. It is found

that the forecasting of spare parts based on the reliability characteristics of an item is one of the

most effective strategies for preventing unplanned stoppage due to lack of spare parts. Kumar et

al. [19] concluded that reliability of equipment is extremely important to maintain quality. This is

achieved by using proper maintenance and design changes for unreliable subsystems and

components of a complex system. It is significant to develop a strategy for maintenance,

replacement and design changes related to those subsystems and components. An analysis of

down time along with causes is essential to identify the unreliable components and subsystems.

The literature review shows that reliability and LCC analysis technique has been applied

to evaluate different types of systems, subsystems and components. These techniques helps to

improve availability, performance and minimize LCC of the system. Most of the researchers

carried out analysis at system level of subsystem level. CNC turning center is having various

subsystem and each subsystem with many components. Reliability of each component is equally

important. In this work it is proposed to carry out reliabilities of components of CNC turning

center and to optimize LCC.

4. Results and Discussion

In this case study, life cycle cost of CNC turning center is optimized using reliability and

maintainability principles. It is essential to grasp and remove the factors and modes responsible

for system failure at various stages of life cycle of CNC turning center. Reliability characteristics

are estimated based on the assessment of trends in field failure data. Reliability analysis and life

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cycle cost optimization is helpful for deciding reliability centered maintenance (RCM) policies.

From the analysis, it is found out that, the components such as spindle bearing, spindle belt,

spindle drawbar, tool, tool holder (disk), Drive Battery, hydraulic pipe, lubricant pipe, Coolant

hose and solenoid valve are critical from reliability and LCC point of view. With certain design

changes and implementation of RCM policy it is found that the reliability of the system is almost

increased by 0.45 and system MTBF is increased from 15000 hours to 17000 hours. Following

conclusions are drawn from reliability analysis and life cycle cost optimization of CNC turning

center:

The initial cost of the CNC turning center should not be the only criteria of procurement. The

initial price of system is around 13% of the life cycle cost.

Maintenance cost, operating cost and support costs dominates the life cycle cost. They

contribute almost 86% of the total LCC.

Certain design modification helps to reduce life cycle cost by 20%.

Further, the total LCC can be optimized by reducing operating cost, failure costs and support

cost.

References

1. Saleh, J., H., and Marais, K., 2006, Highlights from the early (and pre-) history of reliability

engineering, Reliability engineering and system safety, Elsevier, 91 (2006) 249-256.

2. Zio, E., 2009, Reliability engineering: old problems and new challenges, Reliability

engineering and system safety, Elsevier, 94 (2009) 125-141.

3. Barringer, H., P., 1996, An overview of reliability engineering principles, PennWell

conference & exhibitions, Houston, TX, pp. 1-6.

4. Barringer, H., P., 2003, A life cycle cost summary, International conference on maintenance

societies (ICOMS - 2003), Australia, pp. 1-20.

5. Wang, Y., Yam, R., C., M., Zuo, M., J., and Tse, P., 2001, A comprehensive reliability

allocation method for design of CNC lathes, Reliability engineering and system safety,

Elsevier, 72 (2001) 247-252.

6. Wang, Y., Jia, Y., Yu, J., and Yi, S., 1999, Field failure database of CNC lathes, International

journal of quality and reliability management, Emerald, Vol. 16, No. 4, 330-340.

7. Rausand, M., 1998, Reliability centered maintenance, Reliability engineering and system

safety, Elsevier, 60 (1998) 121-132.

8. Crocker, J., and Kumar, U., D., 2000, Age-related maintenance versus reliability centered

maintenance: a case study on areo-engines, Reliability engineering and systems safety,

Elsevier, 67 (2000) 113-118.

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9. Sehgal, R., and Gandhi O., P., 2000, Angra S., Reliability evaluation and selection of rolling

element bearings, reliability engineering and system safety, Elsevier, 68 (2000), pp. 39-52.

10. Barabady, J., and Kumar, U., 2008, Reliability analysis of mining equipment: a case study of

a crushing plant at Jajarm Bauxite mine in Iran, Reliability engineering and system safety,

Elsevier, 93 (2008) 647-653.

11. Louit, D., M., Pascual R., and Jardine, A., K., S., 2009, A practical procedure for the

selection of the time-to-failure models based on the assessment of trends in maintenance data,

Reliability engineering and system safety, Elsevier, 94 (2009) 1618-1628.

12. Castet, J., F., and Saleh, J., H., 2009, Satellite and satellite subsystems reliability: statistical

data analysis and modeling, Reliability engineering and system safety, Elsevier, 94 (2009)

1718-1728.

13. Lad, B., K., and Kulkarni, M., S., 2010, A parameter estimation method for machine tool

reliability analysis using expert judgment, International journal of data analysis techniques

and strategies, Vol. 2, No. 2, pp. 155-169.

14. Godoy, D., R., Pascual, R., and Knights, P., 2013, Critical spare parts ordering decisions

using conditional reliability and stochastic lead time, Reliability engineering and systems

safety, Elsevier, 119 (2013), 199-206.

15. Jaarsveld, W., V., and Dekker, R., Spare parts stock control for redundant systems using

reliability centered maintenance data, Reliability engineering and systems safety, Elsevier, 96

(2011) 1576-1586.

16. Chen, T., Li, J., Jin, P., and Cai, G., 2013, Reusable rocket engine preventive maintenance

scheduling using genetic algorithm, Reliability engineering and systems safety, Elsevier, 114

(2013) 52-60.

17. Wolde, M., T., and Ghobbar, A., A., 2013, Optimizing inspection intervals – reliability and

availability in terms of a cost model: a case study of railway carriers, Reliability engineering

and systems safety, Elsevier, 114 (2013) 137-147.

18. Barabadi, A., Barabady, J., and Markeset, T., 2014, Application of reliability models with

covariates in spare prediction and optimization – a case study, Reliability engineering and

system safety, Elsevier, 123 (2014) 1-7.

19. Kumar, S., Chattopadhyay, G., and Kumar, U., 2007, Reliability Improvement through

Alternative Designs-A Case Study, Reliability engineering and system safety, pp. 983-991.

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7. EXPERIMENTAL METHOD TO CHECK FLOW UNSTEADINESS AND

PRESSURE PULSATIONS IN A NUCLEAR REACTOR COOLANT PUMP

Rahul R. Gaji

Asst. Professor

1. Introduction

Nuclear reactor coolant pump (RCP), the device in the reactor core and the steam

generator to transfer the heat energy [1-3], is the "heart" of a nuclear reactor driving the

circulation flow of the coolant in the main loop. The nuclear reactor coolant pump is the only

rotating part of the nuclear island, so it belongs to the nuclear safety grade one facility. Besides, it

is also the main energy-consuming equipment in the nuclear power plants, which must be

guaranteed to operate continuously for long-term and trouble- free. An investigation on the

internal flow in the mixed-flow nuclear reactor coolant pump is one of the key problems for the

reactor coolant pump development in large pressurized water reactor. Some investigations have

been conducted to study the design of the mixed-flow pump [4,5] and flows instabilities [6,7].

However, most of them only focus on the unsteady pressure pulsation in impeller [8,9] or the

performance of the nuclear reactor coolant pump [10-13]. Unsteady flow structure of a mixed-

flow nuclear reactor coolant pump, especially in some special regions, is very important to the

safety analysis of a nuclear reactor, as it could generate serious flowinduced vibration threatening

the pump integrity [8]. So a comprehensive analysis and prediction of pressure pulsation caused

by intense rotor- stator interaction are essential for the design of the mixed-flow nuclear reactor

coolant pump. At present, in order to improve the efficiency and stable operation of the nuclear

reactor coolant pump, the complicated internal unsteady flow structures should be thoroughly

illustrated.

The nuclear reactor coolant pump has a special structure equipped with a spherical casing,

which determines a typical and complex flow pattern within the pump. Claus Knierim, et al [14]

designed a new type of reactor coolant pump for a 1400 MW nuclear power plant. The impeller

and diffuser were gradually optimized based on the computational fluid dynamics (CFD). The

volute casing is a spherical shape with a discharge nozzle facing the impeller, and flow structures

in the region around the discharge nozzle are uniform. The region of the discharge nozzle itself is

characterized by the fact that the flow below the outlet port is divided into two parts. One portion

flows out of the casing discharge nozzle, whereas the other portion circulates around the casing

once more prior to exiting. Kato et al [15,16] described internal flows of a high-specific-speed

mixed-flow pump at low flow- rates using large-eddy simulation (LES), and it showed that the

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head-flow curve exhibited weak instability characteristics. Antonio Posa et al [17] reported the

LES method using in a mixed-flow pump, where a structured cylindrical coordinate solver with

optimal conservation properties was utilized in conjunction with an immersed- boundary method.

And the overall agreement with the experimental results was excellent, demonstrating the

robustness and feasibility of the approach in rotating machinery applications. It demonstrated that

LES method was adequate to predict complicated flow patterns of a high- specific-speed mixed-

flow pump. With the development of noncontact measuring techniques, unsteady PIV (Particle

Image Velocimetry) [18] and LDV (Laser Doppler Velocimetry) measuring techniques are often

applied to investigate complex unsteady internal flow in pumps, so no external disturbance would

be imposed on the flow field. Miyabe [6,7] used PIV and pressure fluctuation measurements to

investigate the propagation mechanism of a rotating stall in a mixed-flow pump. It was found that

unstable performance was caused by periodical large scale abrupt backflow generated from the

diffuser to the impeller outlet. However, most of the researches focus on the design and the

instability flow of the impeller and diffuser in a mixed-flow pump [19-22], and unsteady flows in

a mixed- flow nuclear reactor coolant pump (here in after referred to as RCP) with the specific

spherical casing are rarely conducted. Consequently, true internal flow structures have not been

thoroughly revealed.

Fig.1 Diagram of mixed flow RCP model

2. Experimental Setup

In order to validate the accuracy of numerical method, experimental investigation of the

RCP model pump is carried out in a closed- loop test rig to guarantee measuring accuracy.

Details of the test loop are shown in Fig.2. The water temperature is about 25 ℃during

experiments. Flow rates of the RCP at various conditions are measured by electronic flow meter

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with an absolute accuracy of ±0.2% of the measured value. Two pressure gauges at the pump

inlet and outlet piping’s are used to obtain the pump head with the accuracy lower than 1%. An

auxiliary pump is used to overcome the pressure drop in the system. The rotating speed of the

RCP model pump was ensured to be at the design value 1480r/min by adopting a frequency

inverter during the experimental process. Fig.2 gives the test used impeller [19].

Fig.2 Test loop and impeller

References

1. Gao, H., Gao, F., Zhao, X., Chen, J., and Cao, X., (2011). Transient flow analysis in

reactor coolant pump systems during flow coastdown period. Nuclear Engineering and

Design, vol.241, no.2, p. 509–514.

2. Poullikkas, A., (2000). Two phase flow performance of nuclear reactor cooling pumps.

Progress in Nuclear Energy, vol.36, no. 2, p. 123–130.

3. Cho, Y.-J., Kim, Y.-S., Cho, S., Kim, S., Kim, Y., Park, J., and Kim, B., (2014).

Advancement of reactor coolant pump (RCP) performance verification test in KAERI.

Proceedings of the 2014 22nd International Conference on Nuclear Engineering

ICONE22, p. 1–6.

4. Bing, H., Cao, S., (2013). Multi-parameter optimization design, numerical simulation and

performance test of mixed-flow pump impeller. Science China Technological Sciences,

vol.56, no. 9, p. 2194–2206.

5. Kim, S., Lee, K.-Y., Kim, J.-H., Kim, J.-H., Jung, U.-H., Choi, Y.-S., (2015). High

performance hydraulic design techniques of mixed-flow pump impeller and diffuser.

Journal of Mechanical Science and Technology, vol.29, no. 1, pp. 227–240.

6. Miyabe, M., Furukawa, A., Maeda, H., Umeki, I., and Jittani, Y., (2008).On improvement

of characteristic instability and internal flow in mixed flow pumps.Journal of Fluid

Science and Technology, vol.3, no. 6, p. 732–743.

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7. Miyabe, M., Maeda, H., Umeki, I., Jittani, Y., (2006). Unstable head-flow characteristic

generation mechanism of a low specific speed mixed flow pump. Journal of Thermal

Science, vol.15, no. 2, p. 115–120.

8. Cheong, J., (2000). An analytical prediction on the pump-induced pressure pulsation in a

pressurized water reactor.Annals of NuclearEnergy, vol.27, no.15, p. 1373–1383.

9. Chun-lin, W., Tong-xiang, Y. I., Zhi-wang, W.,Hong-guang, L., Un, L. J., (2009).

Analysis on pressure fluctuations of unsteady flow field in mixed-flow main coolant

pump.Journal of power engineering, vol.29, no.11, p. 1036– 1040.

10. Bing, H., Cao, S., Tan, L., Zhu, B.,(2013). Effects of meridional flow passage shape on

hydraulic performance of mixed-flow pump impellers. Chinese Journal of Mechanical

Engineering, vol.26, no. 3, p. 469–475.

11. Chan, A. M. C., B, M. K., Nakamura, H., Kukita, Y., (1999). Experimental study of two-

phase pump performance using a full size nuclear reactor pump. Nuclear Engineering and

Design, vol.193, p. 159–172.

12. Xie, R., Shen, F., Wang, X., (2011).A new CFD-based method study on modelling design

of nuclear main pump impeller.Proceedings of the 2011 Asia-Pacific Power and Energy

Engineering Conference. IEEE Computer Society, p. 1–4.

13. Zhang, N., Yang, M., Gao, B., Li, Z., Ni, D., (2015). Experimental investigation on

unsteady pressure pulsation in a centrifugal pump with special slope volute.Journal of

Fluids Engineering, vol.137 (June), p. 061103.

14. Knierim, C., Baumgarten, S., Fritz, J., (2005). Design process for an advanced reactor

coolant pump for a 1400 mw nuclear power plant. 2005 ASME Fluids Engineering

Division Summer Meeting and Exhibition, p. 1–7.

15. Kato, C., Mukai, H., Manabe, A., (2003). Large-Eddy simulation of unsteady flow in a

mixed-flow pump. International Journal of Rotating Machinery, vol.9, p. 345–351.

16. Kato, C., Mukai, H., Manabe, A., (2002). LES of internal flows in a mixed-flow pump

with performance instability. Proceedings of ASME FEDSM2002, p. 1–8.

17. Posa, A., Lippolis, A., Verzicco, R., Balaras, E., (2011). Large-eddy simulations in

mixed- flow pumps using an immersed-boundary method. Computers & Fluids, vol.47,

no.1, p. 33–43.

18. Inoue, Y., Nagahara, T., (2012). Application of PIV for the flow field measurement in a

mixed-flow pump. IOP Conference Series: Earth and Environmental Science, vol.15, no.

2, p. 022011.

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8. ADVANCED CAR TECHNOLOGIES BY 2020

Rajendra V. Pethkar

Associate Professor

Attending auto shows and reading articles over the past one year has my brain awash in

future technology. Mercedes-Benz showed off its fully autonomous F015 Luxury in Motion

concept car in Las Vegas, while Buick, Chevrolet, Hyundai, Infiniti and Volkswagen all had

concepts sporting advanced features in modern cars. Many of these technologies are a ways off,

but others are just around the corner, or even entering showrooms right now. The rate at which

technology is changing personal transportation accelerates every year, which can make predicting

the arrival of future car tech a dicey proposition. This automotive technologies will go from

science fiction to commonplace in just the next 5 years. These listed these below in an effort to

identify the top 10 advanced car technologies we’ll see in showrooms by 2020.

Autonomous Vehicle — let’s just get this one out of the way. Note I didn’t say fully

autonomous vehicle. Why? Because it will take more than 5 years before a car can drive

anywhere, at all times, without human oversight. But by 2020 we’ll have cars capable of being

fully autonomous in certain circumstances, most likely rural interstates with minimal variables

(and no inclement weather). Think early days of cruise control.

Driver Override Systems —This relates to autonomous technology, but it’s different because

it’s the car actively disregarding your commands and making its own decisions. We’ve already

got cars that will stop if you fail to apply the brakes. But by 2020 cars will apply the brakes even

if the driver has the gas pedal floored. The rapid increase in sensor technology will force a shift

in priority, giving the car final say not you.

Biometric Vehicle Access —The switch we’ve seen in recent years from keys to keyless entry

and start will be followed by a switch to key-fob-less entry and start. You’ll be able to unlock

and start your car without anything more than your fingerprint (or maybe your eyeball, but

fingerprint readers are more likely than retina scanners). Sound a lot like the latest form of cell

phone security? It should, because it’s exactly the same concept.

Comprehensive Vehicle Tracking — Insurance companies, and some state governments, are

already talking about fees based on how many miles a person drives. By 2020 insurance

companies will offer a reduced rate for drivers that agree to full tracking of their behaviour. I’m

hopeful this technology remains voluntary, but do I foresee a likely future where insurance

companies will require comprehensive driver tracking? Sadly, yes.

Active Window Displays — Head-Up Display (HUD) technology has come a long way from the

dim, washed out green digits some cars projected on their windshields 20 years ago. But as good

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as HUD is in 2015, by 2020 we will see active glass capable of displaying vibrant images.

Imagine a navigation system that actually highlights the next turn (as seen from your perspective,

through the windshield) as you approach it.

Remote Vehicle Shutdown — This technology already exists, with OnStar leveraging it

regularly. In recent years the telematics company has shut down hundreds of stolen cars, ending

police chases quickly and with little drama. By 2020 remote vehicle shutdown will enter the

social consciousness, negatively impacting nightly news ratings everywhere.

Active Health Monitoring — Ford Motor F +1.18% Company has previewed the idea of

seatbelt or steering wheel sensors that track vital statistics, though the rapid development of

wearable technology means most cars will just wirelessly pair with these devices (think cell

phone for your body). Combine this with basic autonomous technology and you’ve got a car that

can pull over and call paramedics when the driver has a heart attack.

Four-Cylinder Supercar — Ford just showed an all-new GT supercar using a twin-turbo V6.

While it may rub traditional performance enthusiasts the wrong way, a lightweight V6 making

over 600 horsepower will offer world-beating performance, especially if it’s got a light, carbon-

fibre body to pull around. By 2020 we’ll see the first full-fledged, 200-plus mph supercar with a

four-cylinder engine (cubic inches be damned).

Smart/Personalized In-Car Marketing —we already getting Facebook, Twitter and Gmail ads

based on your behaviour. By 2020 the average car will be fully connected to the internet,

meaning your vehicle will provide marketers with a powerful set of metrics to customize their

message. Hopefully these will manifest as an opt-in feature, but get ready for personalized,

location-based ads in your car’s display.

References

1. Seiffert, U., "Review of Recent Activities and Trends in the Field of Automobile

Materials," SAE Technical Paper 810129, 1981, doi: 10.4271/810129.

2. Automotive Engineering (January 2002): “Spark-ignition engine trends”

3. Bernard, L. &Rinolfi R. (2001): “The Future of Engine Technology”, Centro Ricerche

Fiat SCpA, Presentation at Internal Combustion Engines 2001 (Naples), SAE_NA 2001-

01-086

4. Steinemann, P.P. (1999): “R&D Strategies for New Automotive Technologies: Insights

from Fuel Cells”, International Motor Vehicle Program (IMVP),Massachusetts Institute

of Technology, November 1999

5. SadayukiTsugawa, Issues And Recent Trends In Vehicle Safety Communication

Systems,IATSS Research, Science Direct,Volume 29, Issue 1, 2005, Pages 7–15

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9. APPLICATION OF SURROGATE-COUPLED EVOLUTIONARY

COMPUTING TO ENHANCE CENTRIFUGAL-PUMP PERFORMANCE

S. A. I. Bellari

Professor

INTRODUCTION

With the advancement of computational capability, 3-dimensional simulation of any complex

geometries like of turbomachines are possible. Even analysis of multistage pump is possible but

detail analysis takes long time. Optimization of a turbomachines needs large number of

performance data at different design points to generate an objective function. This process may

take long simulation time and indirectly cost of optimization increases. Derakhshan et al. (2013)

reported performance enhancement approach of turbomachines by optimizing its parameters by

experimental and numerical methods. Hundreds of parameters of an impeller can be altered and

the performance can be upgraded. The parameter such as number of blades affects the low-

pressure area at the blade inlet and the jet wake formation in the blade passages (Houlinet al.,

2010). A change in blade angles, changes the hydraulic efficiency and the cavitation formation

(Kamimoto and Matsuoka, 1956; Luo et al., 2008; Sanda and Daniela, 2012). Cao et al. (2004),

Shi et al. (2010) and Marsis et al. (2013) also reported an improvement in pump’s performance

by changing the design parameters.

However, the evaluation of all the parameters for optimization requires a high-dimensional

analysis which is even more time consuming. To avoid this issue a recently developed regression

based techniques which generates low-fidelity model also called as surrogates are being used to

assist engineers to optimize geometry in less time. The issue of ‘dimensionality curse’ of

surrogate models, usually a sensitivity analysis helps to reduce the number of design parameters

(Samad, 2008). Here, the low-fidelity model specifies an approximating function which

approximately mimics the hi-fidelity CFD or CAE model.

The surrogate models used for system optimization are highly dependent on the responses

produced by high-fidelity model (Forrester et al., 2008). The models are also called surrogates,

low-fidelity models, etc. If a designer selects a wrong surrogate for a low-fidelity construction,

he/she may end up with an erroneous result. There are several articles discusses about surrogate

predictions and their comparative study (Zerpa et al., 2005; Goel et al., 2007; Viana et al., 2014).

The commonly used surrogates are response surface approximation (RSA), Kriging (KRG), and

radial basis function (RBF) or neural network. On the other hand, the real life engineering

problems are being solved using single or multi-objective optimization methodologies (Samad et

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al., 2008; Acar and Rais-Rohani, 2009; Forrester and Keane, 2009). But multi-objective

optimization methodology is better in terms of performance enhancement of engineering systems

and the objectives under consideration come under ‘win-win’ strategy. The conflicting objectives

or independent objectives can be correlated through the Pareto optimal front (PoF) (Deb, 2001;

Collette and Siarry; 2003). The multi-objective problems can be solved via weighted-averaging

of the objectives and the formulation is given as:

FC=∑wiFi, where i=1, 2 …n. where, n corresponds to the number of objectives (1)

The non-dominated sorting of genetic algorithm (NSGA-II) and other optimizers such as particle

swarm intelligence etc. for multi-objective optimizations were compared in the literatures and it

was observed that the NSGA-II is extensively used (Marjavaara et al., 2007; Gorissen et al.,

2010; Taormina et al., 2015). There are several commercial as well as non-commercial softwares

like ModeFrontier, SUMO etc., which use surrogate based method along with the multi-objective

Pareto optimal designs (Cravero and Macelloni, 2010; Couckuyt et al., 2011). Jin (2011)

compared surrogates and shown that a neural network can be applied where all ensembled-

members are of the same type of feed-forward neural networks.

Ensembles surrogate methods were developed by several authors (Zerpa et al., 2005; Goel et al.,

2007;Samad et al., 2008; Sanchez et al., 2008; Acar and Rais-Rohani, 2009; Lee and Choi,

2014), assessed and executed for different application areas (Zerpa et al., 2005; Samad et al.,

2008; Marjavaara et al., 2007) for single objective optimizations. The global data based error

measurement gives the fidelity information of the surrogates and can be used to ensemble the

surrogates or to create a weighted average surrogate (WAS). Such a comprehensive WAS based

strategy is required to check the performance of evolutionary algorithms to generate PoF.

Surrogates are problem dependent and one cannot rely on single surrogate for all the problems.

To handle this challenge, an ensembling of surrogates or a concept of weighted average surrogate

(WAS) was introduced. The WAS is based on the average of the predicted error sum of squares

(PRESS), which is implemented from the cross validation (CV) error estimations. As the WAS

includes the contribution from all the surrogates, it gives quite satisfactory results.

Optimization strategy

Figure 1 shows optimization strategy to be performed. It starts with problem formulations which

includes understanding of problem and deciding an objective functions need to be optimized and

the design variables which influences the objective functions.

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This article, gives an introduction to the strategy using multiple-surrogate assisted multi-

objective optimization for the enhancement of pump efficiency.

References

1. Acar, E., Rais-Rohani, M., 2009.Ensemble of metamodels with optimized weight factors.

Structural and Multidisciplinary Optimization. 37(3), 279–294.

2. Cao, S.,Peng, G., Yu, Z., 2004.Hydrodynamic design of rotodynamicpump impeller for

multiphase pumping by combined approach of inverse design and CFD analysis. J. Fluids

Eng., 127(2),330-338.

3. Collette, Y.,Siarry, P., 2003. Multiobjective optimization: Principles and case studies.

Springer,New York.

Fig. 1. Optimization procedure

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4. Couckuyt, I.,Turck, F. D.,Dhaene, T., Gorissen, D., 2011. Automatic surrogate model

type selection during the optimization of expensive black-box problems.Proceedings of

the 2011 Winter Simulation Conference,December 11-14, Phoenix, AZ, USA.

5. Cravero, C.,Macelloni, P., 2010. Design optimization of a multistage axial turbine using a

response surface based strategy. In: Proceedings of the 2nd Int. Conference on Eng.

optimization.1-11.

6. Deb, K., 2001. Multi-objective optimization using evolutionary algorithms, first ed. John

Wiley & Sons, New York.

7. Derakhshan, S., Pourmahdavi, M., Abdolahnejad, E., Reihani, A., Ojaghi, A.,

2013.Numerical shape optimization of a centrifugal pump impeller using artificial bee

colony algorithm. Int. J. Computers & Fluids. 81, 145–151.

8. Forrester, A. I. J.,Sobester, A., Keane, A. J., 2008. Engineering design via surrogate

modeling: A practical guide. John Wiley & Sons Ltd, Chichester.

9. Forrester, A. I. J., Keane, A. J., 2009. Recent advances in surrogate-based optimization.

Progress in Aerospace Sciences. 45(1–3), 50-79.

10. Goel, T.,Haftka, R. T.,Shyy, W.,Queipo, N. V., 2007.Ensemble of surrogates. Structural

and Multidisciplinary Optimization. 33(3), 199–216.

11. Gorissen, D., Couckuyt, I., Laermans, E., Dhaene, T., 2010.Multiobjective global

surrogate modeling dealing with the 5-percent problem.Engineering with

Computers.26(1), 81–98.

12. Houlin, L., Yong, W., Shouqi, Y., Minggao, T., Kai, W., 2010.Effects of blade number on

characteristics of centrifugal pumps. Chinese J. Mech. Eng. 23, 1-6.

13. Jin, M., 2011.Surrogate-assisted evolutionary computation: Recent advances and future

challenges. Swarm and Evolutionary computation. 1(2), 61–70.

14. Kamimoto, G., Matsuoka, Y., 1956. On the flow in the impeller of centrifugal type

hydraulic machinery (The 2nd report).Trans. JSME, Series 3.22(113), 55-59.

15. Lee, Y., Choi, D. H., 2014. Point wise ensemble of meta-models using ν nearest points

cross-validation. Struct. Multidisc. Optimization.Doi: 10.1007/s00158-014-1067-1.

16. Luo, X., Zhang, Y.,Peng, J.,Xu, H.,Yu, W., 2008. Impeller inlet geometry effect on

performance improvement for centrifugal pumps, J. Mech. Science and Tech. 22, 1971-

1976.

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10. DESIGN OF DIE SET FOR INNER LINK PLATE OF STACKER

CHAIN

Satish A. Mullya

Asst. Professor

INTRODUCTION & PROBLEM STATEMENT

Spaco industry is manufacturing stacker for conveying purpose. In stacker, they are

manufacturing inner & outer link chain for rotating conveyer. For that chain, company is making

hemispherical inner link plate with piercing operation. This inner link plate is used for linking a

chain. At present company is producing inner link plate in two separate stages. First stage for

Blanking & second stage for piercing on different die set. This process is time consuming and

harmful to worker while inserting plate for piercing operation. This process consumes more time

for making inner link plate. It is wasting time of one worker as well as cost of one Die set.

1.1 EXISTING SOLUTION

The designed progressive die can make piercing & blanking operation in one stroke. At first

stage, it will perform piercing operation & second stage it will perform blanking operation. Solid

model is designed on design software CATIA. Stress analysis is done on ANSYS workbench to

study stress flow on both punches and deformation of metal. Blanking and Piercing operation can

be done in one stroke of press machine, reducing cycle time. It will reduce cost of one separate

Die set for different operation. It is also safe for handling.

2. CUTTING FORCE AND SHEAR ANGLE

Thickness: 5 mm

For M.S. Material shear strength: 36 kg/mm2

(All dimensions are in mm)

1) Cutting force for blanking:

[(68 * 2) + (Π * 29)]*5* 36

= 40870 Kg = 40.87 tonnes

2) Cutting force for piercing:

[(Π * 14)] *2*5*36

= 15880Kg = 15.88 tonnes

Total cutting force = 40.87 + 15.88

= 56.75 Tonnes

56.75 < 75 Tonnes Available Cutting Force

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We can reduce total cutting force to below available cutting force.

SOLUTION

Shear depth can be provided on punch. This reduces the area in shear at any one time shear also

reduces shock to press and 30% of required cutting force by giving shear depth to punch. Shear

depth can be smooth cut. Cutting forces can be reduced give 2/3 of shear material thickness.

3. SHEAR PROVIDED PUNCH

In Die set design, we have given double shear angle to piercing punch. Shear depth can provided

2/3 thickness of shear material. Inner link plate has 5mm thickness. So 3.33mm shear depth and

29 angle are provided to piercing punch. In design, sharp edges have not been given at the end of

punch because of stress concentration can affected to edge of punch. Cutting forces can be

reduced 30% of required cutting force by giving shear depth to punch. There is nearly 16 tonnes

cutting force required for total piercing operation. After given double angle shear to piercing

punch, required cutting force is reduced 11.2 tonnes from 16 tonnes. So we have saved energy

which consume for additional 4.8 tonnes. We haven’t given shear depth to blanking punch. Shear

area of blanking is large as compare to piercing operation. We can provide shear depth to blank

also but in actual inner link plate is bending by shear angle.

4. DESIGN OF DIE SET

4.1 DIE BLOCK

Dies must be adequately supported on a flat die plate or die holder. Two and only two dowels

should be provided in each block or element that requires accurate and permanent positioning.

They should be located as far apart as possible for maximum locating effect usually near

diagonally opposite corners. Two or more screws should be used depending on the size of die

block.

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Die block thickness (t) is calculated as follows:

t = 15mm for P = 75mm

= 25mm for P = 75 to 250 mm> Actual Total Perimeter of blanking and piercing is 315.46 mm.

Where, P = Blanking Perimeter in mm

We have taken 35mm thickness of die block. A grinding allowance up to 3mm to 5mm should be

added to calculate die thickness. There should be minimum 30mm margin around the opening in

the die block. Die block should never be thinner than 7 to 10mm. The distance is maintained 4

mm from the edge of blank.

4.2 INITIAL STOP WITH DIE BLOCK

Fig. shows the initial stop plate which used at initial for only one stroke of press Machine. In

conventional progressive die set, strip plate comes through strip guide and stop at the first stop

button. At this moment, blanking and piercing both actions takes place, but we get blank plate

without two holes i.e. piercing.

We have created one solution for this problem. We designed die block with two button stop and

placed at sufficient distance from each other. Also we designed one plate which can lock in that

two button stop. We have used fool proof concept to lock that plate on die block for only initial

one stroke.

So we get complete inner link plate with blanking and piercing in only one stroke. This is new

design concept. Due to this design, we saved one blanking plate material as well as saved time

which can be waste to make piercing on 1st Blank Plate.

GUIDE PLATE

The thickness of stripper is 12 mm and the material used is EN 8.

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4.4 DIE SHOE

This is bottom base part of die set. On the die shoe, two pillars are fixed on opposite corner of

base plate. These pillars are used for sliding purpose of punch plate which is fixed to shank.

4.5 PUNCH HOLDER

Fig. shows Punch holder with piercing and blanking punch. Height of punches is 100 mm. Punch

has different material, normally WPS, D2, D3 material can be used for punch and M.S. is used

for punch holder. Upward side of punch holder plate is assembled to shank with press machine.

5. ASSEMBLY OF DIE SET

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6. CONCLUSION

This Die set, Blanking and Piercing operation can be done in one stroke of press machine so die

set reduces cycle time by 50 %. Initial stop provides reduction in the scrap, there is increase in

material utilization by 2 %. Double angle shear is provided to piercing punch, which reduces

cutting force from 16 tonnes to 11.2 tonnes. So cutting force is reduced by 30 %. Maximum

stress 295.39MPa is created on punch and yield strength of punch material is 1500MPa. In result,

we got factor of safety 5. It can sustain at applied 70 tonnes cutting load.

REFERENCES

[1] K.KishoreKumar, Dr.A.Srinath, M.Naveen, R.D.PavanKumar, “Design of Progressive Dies”

(IJERA) ISSN: 2248-9622 Vol. 2, Issue 3, May-Jun2012, pp.2971-2978.

[2] J,R. Paquin, R.E. Crowley, “Die Design Fundamentals”, Second Edition published by

Industrial Press Inc, New York. (45-110).

[3] G.R. Nagpal “Tool Engineering &Design” Sixth Edition, Khanna Publication- Press Tool

Design. (265-327)

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11. NANO GENERATORS: WHAT, HOW AND WHERE?

Sachin A. Urunkar

Asst. Professor

The development of an existing technology is measured in terms of increase in efficiency,

self-sustainability and/or portability. Since the invention of the light bulb, we have always strived

to find a better way to power it. First there was direct current, then alternating current; then the

more portable sources like batteries, rechargeable batteries, fuel cells and technologies involving

the use of alternative resources of energy (wind, solar, hydroelectric, etc.) to power electrical and

electronic devices. But in the field of electronics, size is an important parameter as devices grow

smaller and smaller every day whilst providing a greater amount of power and using lower input

energy.

There is energy everywhere around us in our living environment. It is up to us to figure

out a way to transform this energy to do some useful work. If we just look at our body for

example, it consists of neurons constantly firing electric signals throughout the body to process

response and generate stimuli (electrical energy), it also consists of many links and mechanisms

which do work like when we walk our footsteps generate about 67 Watts of power or our finger

movement produces 0.1 Watts (mechanical energy), chemical reactions take place to release

energy from our food to maintain our body temperature and metabolism (chemical and thermal

energy). Even though these sorts of outputs cannot power big electrical devices, if transformed

accurately it can be used to power small electronic circuits. Nano generators aim to do just that.

In this article we will look into the Nano generators from conception to how they work to what

they hold in store for our future.

What Are Nano Generators?

A Nanogenerator is a term used by scientists to describe a small electronic chip which

transforms mechanical or thermal energy (produced by minute physical reaction) into electricity.

They have an IC (integrated circuit) etched onto an elastic surface, called the substrate, which is

basically the type of circuits that we would find in the electronic devices but at a minute scale as

the term “Nano” implies. Viewed from the naked eye, it looks like lines and boxes but,

underneath all that (when viewed through a microscope), lies a complex system. The goal to be

achieved by a Nanogenerator is provide self-sustainability to the Micro/Nano Systems by

harvesting energy from its environment. It was first proposed by Dr. Zhong Lin Wang and his

colleagues at Georgia Institute of Technology in 2006 and they had developed the first

Nanogenerator for a self-powered system [1],[2].

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Fig.01 Naogenerator Circuit

Mechanical is energy although small, is available in plenty in various forms in the

environment. It can be light wind, body motion, muscle stretching, sound waves, noises,

vibrations, blood flow etc. The table below shows the mechanical energy from typical body

motions and the theoretical electric energy that can be obtained from it.

Table 1 Table showing biomechanical energies related to normal body functions

Physical Activity

Mechanical

Energy

Equivalent

Theoretical

Electrical

Energy

Electrical Energy

per Movement

1. Blood Flow 0.93 W 0.16 W 0.16 J

2. Exhalation 1.00 W 0.17 W 1.02 J

3. Breath 0.83W 0.14 W 0.84

4. Upper Limb Motion 3.0 0.51 2.25

5. Walking 67 W 11-39 W 18.80 J

To convert the mechanical energy into electricity, Nanogenerators use arrays of

“Nanowires” which are made of piezoelectric zinc oxide (ceramic) material [2]. Piezoelectric

materials produce a potential difference when they are strained. The strain is provided by the

environment which these piezoelectric nanowire arrays convert to electric potential. The straining

force results in a transient flow of electrons in the external load because of the “Piezopotential”.

The advantage of using these nanowires is that they can be triggered by a tiny external force at

wide range of excitation frequencies (One Hz to thousands of Hz). By combining the effects of

thousands of such piezoelectric nanowires, a gentle strain can produce about 1.2V of electricity

which can power an LED and a small LCD unit [2].

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Nano Materials for Nanogenerators

Among the materials used in nanotechnology, ZnO (Zinc Oxide), a semiconducting

ceramic material, is one of the most common choices as it has abundant configurations required

from a nanomaterial. It has a wide range of applications in Optics, optoelectronics, biomedical

science, sensors, actuators, energy and spintronics. Under normal conditions, it has a Wurtzite

structure which is a type of hexagonal crystal system. Its structure is the main reason why it is a

widely used semiconductor. Although the whole unit cell is neutral, the lack of symmetry in the

cell (a tetragonal structure within the HCP (Hexagonal Closely Packed) configuration, some of

the surfaces of the material are terminated with a larger concentration of free charges. These

polar charge surfaces give rise to some unique growth phenomena. The nanowires are mostly

grown in hexagonal rod like or belt like shapes. Some of the common methods to produce

nanowires are,

1. Vapor-Solid-Solid (VSS) process;

2. Vapor-Liquid-Solid (VLS) process;

3. Pulsed Laser Deposition (PLD);

4. Chemical Approach.

Fig.02 ZnO Nanowires grown on sapphire substrate using gold catalyst

These processes produce nanowires in shapes of rods and belts depending on the various

specifications needed [7]. Each nanowire measures around 100 to 300 nm in thickness

(0.0000001 to 0.0000003 meters!) and lengths of about 100 microns which is equal to

100,000nm (which is roughly equal to the width of two human hairs). Besides ZnO nanowires,

other wurtzite structures like CdS, GaN and InN are being used for electricity generation [5],[6].

Out of these, GaN and InN are quite encouraging as they can produce an output voltage of about

1V per nanowire.

Working Mechanism

Arrays of thousands of these nanowires are grown on a conductive solid substrate and a

silicon electrode coated with Platinum is placed on the open end of the nanowires in a zig zag

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pattern. The force applied on the nanowires can either be perpendicular to the axis of the

nanowires (bending force) or parallel (compressive or tensile force). When the external force is

applied on the tip of the nanowire, there is a deformation caused in the nanowire structure due to

the displacement of ions causing the piezoelectric effect. In a perpendicular force, i.e. a laterally

moving electrode tip causes a voltage difference between the compressed end (negative terminal)

and the stretched end (positive terminal); whereas in the case that there is parallel force, i.e. a

pressing or pulling force, the voltage difference is formed between the top end and bottom end of

the nanowires.

Fig.03 Force perpendicular (left) and parallel (right) to the axis of NW

The electrical contact between the nanowire tip and the silicon electrode must be a

Schottky Contact which is a type of contact between a metal-semiconductor junction allowing

charge to flow in one direction only with rectification (otherwise it will be an Ohmic Contact).

The charge produce from the piezoelectric material is captured by the Silicon Electrode and

passed on through the circuit of the Nanogenerator. The entire Nanogenerator unit may have

multiple electrodes collecting charge from millions of Nanowires. There is also development

being done on two other types of Nanogenerators using a different effect rather than the

piezoelectric effect. They are 1) Tribo-Electric Nanogenerators (TENG) and 2) Pyro-Electric

Nanogenerators (PENG).

The triboelectric effect is better known to us as electrostatic induction. When a certain

material comes into frictive force (rubbed) onto another material, it produces a stagnation of

electrostatic charge. For example, when a balloon is rubbed with fur and placed above our head,

strands of hair are attracted by the induced electrostatic force on the surface of the balloon. The

vibration energy causing the triboelectric effect are captured by organic films having opposite

tribo-polarity constantly going in and coming out of contact.

The Pyroelectric Nanogenerators work on the Seebeck effect to convert thermal energy

into electricity. When two materials are joined and heated, they generate electricity at the

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junction. PENGs can be used in an environment which has a fluctuating time dependent

temperature profile. This can prove to power wireless thermal sensors, medical diagnostics,

personal electronics (like when your smartphone gets over heated and all of that energy is

wasted?) and thermal imaging equipment.

Practical Applications of NG

The main application of Nanogenerators is to harvest biomechanical energies from living

species to power medical implants. Today’s medical-electronic implants either requires constant

changing or an external power source to keep them running, such as a peacemaker or a blood

glucose monitor. If these Nanogenerators can harvest the energy from involuntary events like our

heart beat, blood flow, lung expansion etc. and power the equipment which help them save our

life (a mutual symbiosis). It also helps that the piezoelectric materials like ZnO are absolutely

non-toxic and can be synthesized on an organic substrate [3]. Another important application is in

the measurement and metrology industry, self-powered sensors such as UV and pH sensors

generally the Nano and micro devices. Nanogenerators could even power iPods and smartphones

in the near future with Nanogenerators implanted in the cloth fiber of our shirts, hoodies, shoes,

gloves etc. which could provide music when you go for your morning jog. Futuristic approaches

towards the use of nanogenerators include the utilization of Nanogenerators in wearable

technology like smart optics, smart fiber etc. Also considering the impact it has on the

environment by producing clean energy by utilizing the energy of life [4].

Technologies these days tend to make people lazier but this innovative technology could

improve the general fitness standards of today’s population. The application of NGs is only

limited by one’s imagination. The invention of nanogenerators is on the top 10 world inventions

as proposed by Chinese Academy of Science. Piezonanoelectronics has been listed as one of the

top ten emerging technologies in 2009 by MIT Technology Review. Research is constantly being

done in this front by leading Universities and Laboratories, and will probably be the invention

that caused a revolution in the field of electronics in the coming 30 to 40 years.

References:

1. Z.L. Wang and J.H. Song, “Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire

Arrays,” Science, vol. 312, no.5771, 2006, pp. 242–246.

2. J.H. Song, J. Zhou, and Z.L. Wang, “Piezoelectric and Semiconducting Coupled Power

Generating Process of a Single ZnO Belt/Wire. A Technology for Harvesting Electricity

from the Environment,” Nano Letters, vol. 6, no. 8, 2006, pp. 1656–1662.

3. Z.L. Wang, “The New Field of Nanopiezotronics,” Materials Today, vol. 10, no. 5, 2007,

pp. 20–28.

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4. Z.L. Wang, “Nanopiezotronics,” Advanced Materials, vol. 19, no. 6, 2007, pp. 889–992.

5. P. X. Gao et al., “Nanowire Piezoelectric Nanogenerators on Plastic Substrates as

Flexible Power Sources for Nanodevices,” Advanced Materials, vol. 19, no. 1, 2007, pp.

67–72.

6. Yang, R. S.; Qin, Y.; Dai, L. M.; Wang, Z. L. Power generation with laterally packaged

piezoelectric fine wires. Nat. Nanotechnol. 2009, 4, 34–39.

7. Kim, D. Y.; Lee, S.; Lin, Z.-H.; Choi, K. H.; Doo, S. G.; Chang, H.; Leem, J.-Y.; Wang,

Z. L.; Kim, S.-O. High temperature processed ZnO nanorods using flexible and

transparent mica substrates for dye-sensitized solar cells and piezoelectric

nanogenerators. Nano Energy 2014, 9, 101–111.

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12. WATER TOWERS

Sandip S. Chavan

Asst. Professor

It's no surprise that water towers store water, but it's less well known that they also store

energy. The whole process starts at the water treatment plant. After the water is treated,

electronically powered mechanical pumps send it through pipes, either to serve an immediate

need (think showers, dishwashers and water sprinklers) or to a water tower for storage. Many

water towers are tall and look like giant lollipops. Because the pumps from the treatment plant

send the water up into the water tower's tank, the water gains potential energy, or stored energy.

This energy allows the water to flow out of the tank, turning its potential energy into kinetic

energy (energy of motion) moreover, the taller the water tower, the more potential energy the

water. But if a water tower is designated to hold water for a large metropolitan area that's far

away, it will likely be tall and have an enormous tank.

A standard water tower can hold 50 times the volume of a regular backyard swimming

pool, which holds about 20,000 to 30,000 gallons (about 76,000 to 114,000 liters) of water, For

instance, "The Giant Peach" water tower in Gaffney, South Carolina, which also serves as a

tourist attraction, is 150 feet (46 meters) tall and holds 1 million gallons (3.8 million liters) of

water. Water towers typically fill up when demand for water is low. This usually happens at night

after most people go to bed. The pumps at the water treatment plant continue to send out water,

but instead of going to people's sinks, the water goes into water towers for storage.

Blue and white water towers in Kuwait.

Then, during the morning rush when people are running water to brush their teeth, take

showers and brew coffee that stored water, in addition to the water coming from the treatment

plant, is available to through pipes to homes. Water towers also ensure that there's a supply of

water during power outages, at least until the water runs out. During an electricity outage, the

pumps at the water treatment plant would likely stop working (unless there's a generator), Inniss

said. But because the water in the tower already has potential energy, it doesn't need more

electricity to flow out of the tank.

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13. KNOWLEDGE BASED ENGINEERING - IN PRODUCT DEVELOPMENT

Sumit V. Patil

Asst. Professor

What is KBE?

It creates specialized design environment that can automate the product design.

Apply formal design rules & constrains.

Leverage the companies design & manufacturing experience.

KBE is fundamentally about using ability, experience, expertise and other information

relevant to each phase of the engineering life cycle of an product to it’s fullest advantage.

KBE is a mature methodology that bridges the gap between knowledge management &

design automation, integrating their best feature with today’s proven product development tool

like CAD, CAE, etc. to provide real results to some of the biggest challenges manufacturers &

engineering organizations face today.

Background

The design engineer’s dilemma is to develop improves and less expensive products that

can be manufactured in less time. These demands are the challenge for every design engineer. In

order to achieve this, the product development process has to be refined and improved.

In the late 70’s design drawing tables started to be changed for computers and products

could be developed in a two-dimensional computer environment rather than on paper. This was a

big step and made the modeling process easier. Around ten years later the first solid modeling

systems were employed, i.e. CAE/CAD/CAM. This again was a big improvement and basically

gave a new dimension to design work by enabling a better overview and an important step into

the paradigm of virtual prototyping.

The next big step for the product development process was when all its players were

started to be integrated in the beginning of the 90’s. Since then the integrated product

development process has been improved in different ways. One way which lately has increased

in popularity is utilizing a tool named Knowledge Based Engineering (KBE). It is stated that

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KBE will have the same importance for companies in 2015 that CAE/ CAD/CAM had in the

90’s.

The concept is not brand new- it goes back to the 50’s. At this time research were

performed with the objective of developing a system which had an own intelligence, known as

Artificial Intelligence (AI). The idea of AI was to implement adaptive solving strategies that

could be used to solve a broad spectrum of tasks. However, the resulting system was a

disappointment. The simple problems the system manages to solve humans could do much faster.

Today knowledge based system (KBS) or expert system are closest related to AI.

The key to success was to let the engineer do the creative work and use the computer to

automate routine work. In the beginning of the 80’s researchers started to store knowledge and

rules in systems which then managed to perform mundane tasks of the product development

process. The concept of KBE was born.

Today’s Research

An important issue in research about KBE-system is how to reduce development time.

Therefore development methodologies have been proposed. It is also of interest to optimize the

use of KBE for Small and Medium sized Enterprises (SME’s). Today’s it is expensive for SMEs

to implement KBE- system and therefore methodologies for KBE development have been

proposed. It proposed that the organizational structure is mapped up and fields where the

company can gain from KBE are identified. Another research topic is how to expand the

capabilities of process integration in KBE. Manufacturing evaluation has shown being possible

using KBE. The question is now how advanced the implemented rules can be made and if tools

other than KBE application from CAE- software are needed to enabled evaluation of

manufacturing to proposed concepts.

KBE Fundamentals

KBE can be defined as:

The use of advanced software techniques to capture and re-use product and process

knowledge in an integrated way. The main objective of KBE is to reduce lead-time by capturing

product and process knowledge. The core of the system is the product model where product and

process knowledge is stored, see figure 1. External database are used for tabled data. Input to the

KBE system is usually customer’s specification which in turn gives several kinds of output when

being processed. The system software is objective-oriented and can therefore perform demand-

driven calculations.

A product can often be divided into several parts which contains the details. An airplane

can be divided into sections; forward, mid, aft and after body which in turn can be divided further

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on. The parts are managed by an object-oriented system that specifies the relationship to sub and

super parts.

INPUT PRODUCT MODEL OUTPUT

Customer Specifications Geometry Reports

Product Data Configuration Drawings

Engineering Knowledge Costs

BOM

Manufacturing Plans

EXTERNAL DATA CAD Models

Catalogues Table

Materials Analysis

FIG. 1. The KBE system

Objective:

The main objective with KBE system is reducing lead-time by automating mundane work

activities of the product development process. Capturing knowledge from staff is another

objective. This makes the company more resistant to staff turnover.

It has also been stated, that KBE could be a useful tools to support and organise the new

functional approach in product development where a product can be seen as a service rather than

“Just” a physical product. The product can then include maintenance, education and more “Soft”

properties than the traditional product. Today there are not other tools available for development

of such functional products. By developing product model these objectives can be met.

Knowledge based engineering application lifecycle

Developing knowledge-based application creates difficulties to knowledge engineers.

Knowledge-based project cannot be handled by general software engineering methodology. The

lifecycle of knowledge based application and software application is different in many aspects. In

order to achieve the objective of knowledge engineering, Knowledge-Based Engineering (KBE)

application lifecycle focuses on these six critical phases as shown in figure 2.

FIG.2. Knowledge based engineering application lifecycle

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IDENTIFY: Before using KBE a designer must first identify a product to see if KBE is at all

needed. This is the step where type of KBE system is determined, if it is needed at all. The

outcome from this step is a conceptual specification of the KBE application. IDENTIFY is also

triggered by ACTIVATE if more information is needed about the implementation environmental.

JUSTIFY: The aim of this step is to create a project plan and to seek management approval by

examining possible risk concerning, cultural and technical matters for example.

CAPTURE: In this step the raw knowledge is collected and structured into the “Informal Model”

by using ICARE forms (Illustration, constraint, Activity, Rules and Entity forms).The relation

between the ICARE elements are described by process and hierarchy charts.

FORMALIZE: The “Formal Model” is created from the “Informal Model”. The modeling

language used is MOKA Modeling language (MML) which is based on the Universal Modeling

Language (UML).

PACKAGE: Now the formal Model will be implemented to a KBE- system.

ACTIVATE: This step includes installation, distribution and support of the KBE- system. It may

also trigger the IDENTIFY step if it concluded that more information about the

implementation environment is needed.

Revolution or Evolution?

Even though the discipline of engineering design can benefit from KBE systems there are still

some drawbacks that need to be removed through research.

Benefits

The most obvious benefit from using a KBE system is the reduced lead-time. It is also easier to

optimize products by capturing knowledge, staff turnover is not a big problem. Because time

demanding routine tasks are automated more time for creative solutions are given.

i) Reduced lead-time

The major fit is that KBE system reduces the lead-time. This is highly pronounced for

product development of products with the following properties.

- Products with high degree of similarity between versions.

o The higher similarity the more knowledge can be re-used

- Products requirements a large amount of design configurations (e.g. geometry

configuration, material alternatives, etc.)

o Design configurations are suitable to be controlled by rules.

- Product with a large number of design processes (e.g. FEA, cost calculation.

weight calculation)

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o These design processes can be performed automatically in an “one button

push” matter if all needed input is given to the KBE- system.

ii) Product Optimisation

Optimising the design is easy- trial and error goes fast. The user can try many “what ifs”

and come to a conclusion after a radically smaller amount of time than before. The computer can

also search for the best configuration within a specified range.

iii) Knowledge capture

Staff turnover is no longer a big problem for companies using KBE because base

knowledge is stored in the product model. This also implies that companies can reduce their

outsourcing activities when basic knowledge is stored and handled by the KBE - system.

iv) More time for innovation

By automation mundane, routine work time for the product developer to concentrate on

innovative solutions is given. On a long – term view this is increasing the product value and

enhances the company’s business.

Drawbacks

The major drawback with KBE is that it takes a great deal of time to build up the product models.

An important aspect which sometimes is neglected is the knowledge transfer, how knowledge is

spread in the company.

i) Time Demanding Building Product Models

A KBE system can reduce the lead time when implemented correctly. This implementing process

is however quite time demanding. A KBE system can be seen as a new engineer joining the

department. The system has to be educated like the new engineer who in the beginning will learn

the basic tasks that are performed often. It takes a while before the new engineer can perform

tasks that the company can benefit from.

ii) Knowledge transfer

A danger with any computer system is if it becomes a “black box”. You put something in

and you get something out, but what happens in between, nobody known. A result generated

from a computer system is often regards with more respect than it deserves. This gives a false

security and can lead to problems if system contains faults. When a system becomes a “black

box” there is a problem to transfer the captured knowledge to new employees. Therefore it is of

great importance that the systems provide an understanding of the process of reaching the results

by explaining what has been done.

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References

1. Development of Knowledge Based Engineering Support for Design and Analysis of Car

Components Using NX – Knowledge Fusion; MOHAMEED GOLKAR Master Thesis for

Master of Science Programme in Space Engineering

2. Knowledge Engineering Technique for Cluster Development Pradorn Sureephong , Nopasit

Chakpitak, Yacine Ouzroute, Gilles Neubert, and Abdelaziz Bouras.

3. MOKA - A Methodology and tools Oriented to Knowledge-based engineering Applications

Keith OLDHAM, Stephen KNEEBONE, Martine CALLOT, Adrian MURTO, Richard

BRIMBLE.

4. Knowledge-Based Engineering Systems: Applying Discipline And Technology For

Competitive Advantage D. H. Brown Associates Port Chester, New York.

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14. HEAT TRANSFER ENHANCEMENT FROM DISCRETE FINS

SUJIT V. Yadav

Asst. Professor

The operation of many engineering systems results in the generation of heat. This

unwanted by-product can cause serious overheating problems and sometimes leads to failure of

the system. The heat generated within a system must be dissipated to its surrounding in order to

maintain the system at its recommended working temperatures and functioning effectively and

reliably. This is especially important in modern electronic systems, in which the packaging

density of circuits can be high. In order to overcome this problem, thermal systems with effective

emitters as fins are desirable.

In order to achieve the desired rate of heat dissipation, with the least amount of material,

the optimal combination of geometry and orientation of the finned surface is required. Among

the geometrical variations, rectangular fins are the most commonly encountered fin geometry

because of their simple construction, cheap cost and effective cooling capability. Two common

orientations of rectangular fin configurations, horizontally based vertical fins and vertically based

vertical fins, have been widely used in the applications.

The heat dissipation from the finned systems to the external ambient atmosphere can be

obtained by using the mechanisms of the convection and radiation heat transfer. The effect of

radiation contribution in total heat transfer rate is quite low due to low emissivity values of used

fin materials, such as duralumin and aluminium alloys. The basic equation describing such heat

losses is given by:

= ℎ ∗ ∗ Δ

As seen from above equation, the rate of heat dissipation from the surface can be

increased either by increasing the heat transfer coefficient, h or by increasing the surface area, A.

An enhanced value of h can usually be achieved by creating appropriate conditions of forced

flow over the surface. Although such forced convection is effective, extra space will be needed to

accommodate a fan which causes additional initial and operational costs. Therefore, forced

convection is not always preferable. Since the use of extended surfaces is often more economical,

convenient and trouble free, most proposed application of increasing surface area is adding fins

to the surface in order to achieve required rate of heat transfer. However, the designer should

optimize the spacing or the number of fins on base carefully; otherwise fin additions may cause

the deterioration of the rate of heat transfer. Although adding numerous fins increases the surface

area, they may resist the air flow and cause boundary layer interferences which affect the heat

transfer adversely.

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Discrete fins

The permeable fin (figure 1) is made by making hole or square in fins along fin thickness and fin

length. Also perforated fin are making hole and square along fin thickness. Permeable fin is

shown as figure 1. Discrete means make a discontinuous. By cutting solid fin made it

discontinuous discrete fin is made up by cutting the solid fin along the fin thickness with varying

cut width.

Figure1. Photograph of Permeable fin array with two rows of holes

Figure2. Array of solid fin and Permeable fin

These cutting slots are along the fin width and their cross section is perpendicular to the fluid

flow direction. Selecting smaller size makes the flow laminar in the channel and increasing more

channels is not possible due to fin dimension and shape. The theoretical work on flow and heat

transfer for an array of three-dimensional discrete fins with the shape mounted on a flat plate.

(a) Solid fins array

(b) Permeable fins with two rows of inline holes

(c) Permeable fins with staggered holes

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a) b)

Figure3. Discrete fin with a) inline and b) staggered arrangement

The experimental and numerical investigation is done by varying parameters like number of cut

(3-5), depth of cut (1/4th of protrusion length-full protrusion length) and width of cut (2, 4, 5

mm) with constant fin thickness of 2 mm. The heat input is varied from 15-45 W, which is the

normal range for most of the application. The flow field of natural convection is observed hat full

depth of cut more efficient than other depth of cut. For natural convection from Figure 5.6 the

effect of extending the depth of cut of fin from ¼ to full is results in higher steady-state

convective heat dissipation from the fin arrays.

The temperature contours is observed for depth of cut, number of cut and width of cut:

Figure a) Temperature counters of 3 No. of cut with varying depth of cut 333 K

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Figure b) Temperature counters of 2 mm width of cut at 333 K

Figure c) Temperature counters for 3 No. of cut at 333 K

References:

1. Akyol U., Bilen K., 2006, ‘Heat transfer and thermal performance analysis of a surface with

hollow rectangular fins’, Applied Thermal Engineering 26 209–216.

2. Pise A.T. and Awasarmol U.V., 2010, ‘Augmentation of natural convection hat transfer

from cylinder with permeable fins’, ISHMT-ASME Heat and Mass Transfer Conference,

January.

3. Khomane S.G., Gunvat P. S., Pise A.T., ‘Investigation of Enhancement of Heat Transfer

from Discrete Fins’, NCRAME-2013, PP-42

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15. ULTRASONIC VIBRATIONS ASSISTED IN EDM

Vaibhav S. Ganachari

Asst. Professor

1.1 Introduction:-

Electrical discharge machining is a machining method primarily used for hard metals or

those that would be very difficult to machine with traditional techniques. EDM typically works

with materials that are electrically conductive, although methods for machining insulating

ceramics with EDM have also been proposed. EDM can cut intricate contours or cavities in pre-

hardened steel without the need for heat treatment to soften and re-harden them. This method can

be used with any other metal or metal alloy such as titanium, hastelloy. Also, applications of this

process to shape polycrystalline diamond tools have been reported. EDM is often included in the

‘non-traditional’ or ‘non-conventional’ group of machining methods together with processes such

as electrochemical machining (ECM), water jet cutting (WJ, AWJ), laser cutting and opposite to

the ‘conventional’ group (turning, milling, grinding, drilling and any other process whose

material removal mechanism is essentially based on mechanical forces)[1] .

Ideally, EDM can be seen as a series of breakdown and restoration of the liquid dielectric

in-between the electrodes. However, caution should be exerted in considering such a statement

because it is an idealized model of the process, introduced to describe the fundamental ideas

underlying the process. Yet, any practical application involves many aspects that may also need

to be considered. For instance, the removal of the debris from the inter-electrode volume is likely

to be always partial. Thus the electrical proprieties of the dielectric in the inter-electrodes volume

can be different from their nominal values and can even vary with time. The inter-electrode

distance, often also referred to as spark-gap, is the end result of the control algorithms of the

specific machine used. The control of such a distance appears logically to be central to this

process. Also, not all of the current between the dielectric is of the ideal type described above:

the spark-gap can be short-circuited by the debris.

2.1 EDM with Ultrasonic vibration :-

Introduction of ultrasonic vibration to the electrode is one of the methods used to expand

the application of EDM and to improve the machining performance on difficult to machine

materials. The study of the effects on ultrasonic vibration of the electrode on EDM has been

undertaken since mid 1980s. The higher efficiency gained by the employment of ultrasonic

vibration is mainly attributed to the improvement in dielectric circulation which facilitates the

debris removal and the creation of a large pressure change between the electrode and the work

piece, as an enhancement of molten metal ejection from the surface of the work piece . Zhang et

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al. [1] proposed spark erosion with ultrasonic frequency using a DC power supply instead of the

usual pulse power supply. The pulse discharge is produced by the relative motion between the

tool and work piece simplifying the equipment and reducing its cost. They have indicated that it

is easy to produce a combined technology which benefits from the virtues of ultrasonic

machining and EDM. Fig. 1 shows the progress of method in combining ultrasonic vibration with

EDM from year 1995 to 2006. The method starts with vibrating the electrode followed by

vibrating the work piece in year 1999, which gains popularity from year 2002 and continues until

year 2006.

Figure 2.1:-Progress of method in combining ultrasonic vibration with EDM from 1995 to 2006.

2.2 The Advancement In USEDM:

It is generally considered that dielectric liquid medium is necessary in the process of

EDM. However, some unwanted gases are always generated in the machining process, which

will pollute the environment and do harm to the operator’s health. Health, safety and

environment are important aspects, particularly when hydrocarbon oil is used. So the green

method of EDM without pollution aimed to protect environment has become a hot studying

subject in the word recently. The trend of electrical discharge machining in the world is to

develop green EDM technology with high efficiency, low waste and no pollution [2].

Gas medium electrical discharge machining is a new technology, which was proposed by

Kunieda and Yoshida (1997). The pollution decreases in this method because the EDM is

achieved in gas medium instead of kerosene-based oils or mineral oils. Moreover, the electrode

erosion rate is very low when selecting appropriate gas medium and rarely affected by impulse-

on time. While process instability and arcing failure in electrical discharge machining in gas are

still serious problems in practice especially when high erosion rates are attempted. To improve

the machining efficiency and quality, ultrasonic vibration assisted EDM in gas was proposed In

this new technology, the tool electrode is formed to be tubular, which vibrates with ultrasonic

frequency and rotates with the axis synchronously, as Fig.2.2shows. The high pressure velocity

gas is supplied through the internal hole of the electrode and flow over the discharging gap,

which can enhance the removal of molten and evaporated work piece material. Also, it cools and

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solidifies the removed material and prevents them from adheringonto the surface of the tool

electrode. Furthermore, during the pulse-off time, the gas with a high velocity blows off the

plasma formed by the previous discharge guaranteeing the recovery of the dielectric strength of

the gap, and decreases the temperature of the discharge spot on the tool electrode and the work

piece due to heat transfer. All these endow the technology with high machining efficiency and

wide machining range [2].

Figure 2.2:- The Principle of USEDM in Gas [2].

Results :

Figure 2.2:- Comparison of traditional EDM in gas & USEDM in Gas [2].

Conclusions:

1. Ultrasonic assisted EDM has the potential for deep hole drilling an aspect ratio of 20 has

been achieved in the machining of micro holes in this study.

2. Another benefit of ultrasonic vibration is that the savings in machining time. It is also

noticed that the ultrasonic vibration causes some shape distortion and produces rougher

machined surface.

3. The MRR of UEDM in gas is much higher compared with EDM in gas and conventional

EDM in dielectric liquid.

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Refrences:

1. M. R. Shabgard, B. Sadizadeh, H. KakoulvandWorld Academy of Science, Engineering

and Technology 52 2009.

2. Q.H. Zhang, J.H. Zhang, S.F. Ren, J.X. Deng, X. Ai School of Mechanical Engineering,

Shandong University, Jinan 250061, China.

3. B.H. Yan A,∗, A.C. Wang A, C.Y. Huang A, F.Y. Huang A A Department Of

Mechanical Engineering, National Central University, Chung-Li, Taiwan 32054, ROC.

4. SrideviBilla, Murali M. Sundaram and Kamlakar P. Rajurkar Center for Nontraditional

Manufacturing Research, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.

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16. RAPID PROTOTYPING: INTRODUCTION

Vinayak T. Kumbhar

Asst. Professor

A Prototype is an important and vital part of the product development process. In any

design practice, the world prototype is often not far from the things that the designer involved in.

Oxford Advanced Learner’s Dictionary of Current English defines it as, “A prototype is the first

or original example of something that has been or will be copied or developed; it is model or

preliminary version. e. g. A prototype supersonic aircraft”.

To be general enough to be able to cover all aspects of the meaning of the world

prototype for use in design, it is very loosely define here as, “An approximation of a product or

its component in some form for a definite purpose in its implementation.”

It is very general definition departs from the usual accepted concepts of the prototype

being physical. It covers all kinds of prototype used in the product development process,

including objects like mathematical model, pencil sketches, foam models and of course the

functional physical approximation of the product.

Various Aspects of Prototype-

The general definition of the prototype contains three aspects of interest;

The implementation of the prototype; from the entire product (or system) itself to its sub-

assemblies and components.

The form of the prototype; from the virtual prototype to a physical prototype, and

The degree of the approximation of the prototype; from a very rough representation to a

exact replication of the product.

The implementation aspect of the prototype covers the range of prototyping the complete

product (or system) to prototyping part of, or a sub-assembly or a component of the product. The

complete prototype as its name suggests, models most, if not all the characteristics of the product.

One example of such a prototype is one that is given to a group of carefully selected people with

a special interest, often called a focus group, to examine and identify outstanding problems

before the product is confirmed to the final design. On the other hand there are prototypes needed

to study or investigate special problems associated with one component, sub-assembly or simply

a particular concept of the product that requires close attention. An example of such a prototype

is a test platform that is used to find the comfortable rest angles of an office chair that will reduce

the risk of the spinal injuries after prolonged sitting on such a chair.

The second aspect of the form of prototype takes into account how the prototype

is being implemented. On one end, virtual prototype that refers to prototypes that are non-

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tangible, usually represented in some form other than physical e.g. mathematical model of

control system. An example is the visualization of the airflow over an aircraft wing to ascertain

lift and drag on the wing during supersonic flight. The physical model on the other hand, is the

tangible manifestation of the product, usually built for testing and experimentation. Example of

such a prototype include a mock-up of cellular telephones that looks and feels very much like the

real product but without its intended functions. Such a prototype may be used purely for aesthetic

and human factor evaluation.

Roles of the Prototypes-

The roles that prototypes play in the product development process areseveral. They include the

following:

(1) Experimentation and learning

(2) Testing and proofing

(3) Communication and interaction

(4) Synthesis and integration

(5) Scheduling and markers

To the product development team, prototypes can be used to help the thinking, planning,

experimenting and learning processes whilst designingthe product. Questions and doubts

regarding certain issues of thedesign can be addressed by building and studying the prototype.

Forexample, in designing the appropriate elbow-support of an office chair,several physical

prototypes of such elbow supports can be built to learnabout the “feel” of the elbow support

when performing typical tasks onthe office chair.

Prototypes can also be used for testing and proofing of ideas andconcepts relating to the

development of the product. For example, in theearly design of folding reading glasses for the

elderly, concepts and ideas of folding mechanism can be tested by building rough physical

prototypes to test and prove these ideas to see if they work as intended.

The prototype also serves the purpose of communicating information and demonstrating ideas,

not just within the product development team,but also to management and client (whether in-

house or external). Nothing is clearer for explanation or communication of an idea than a

physical prototype where the intended audience can have the full experience of the visual and

tactile feel of the product. A three-dimensional representation is often more superior than that of

a two-dimensional sketch of the product. For example, a physical prototype of a cellular phone

can be presented to carefully selected customers. Customers can handle and experiment with the

phone and give feedback to the development team on the features of and interactions with the

phone, thus providing valuableinformation for the team to improve its design.

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A prototype can also be used to synthesize the entire product conceptby bringing the

various components and sub-assemblies together to ensure that they will work together. This will

greatly help in the integration of the product and surface any problems that are related toputting

the product together. An example is a complete or comprehensive functional prototype of

personal digital assistant (PDA). When putting the prototype together, all aspects of the design,

including manufacturing and assembly issues will have to be addressed, thus enabling the

different functional members of the product development team to understand thevarious

problems associated with putting the product together

Historical Development-

The development of Rapid Prototyping is closely tied in with thedevelopment of applications of

computers in the industry. The declining cost of computers, especially of personal and mini

computers, has changed the way a factory works. The increase in the use of computershas

spurred the advancement in many computer-related areas including Computer-Aided Design

(CAD), Computer-Aided Manufacturing (CAM) and Computer Numerical Control (CNC)

machine tools. In particular, the emergence of RP systems could not have been possible

withoutthe existence of CAD. However, from careful examinations of the numerous RP systems

in existence today, it can be easily deduced that other than CAD, many other technologies and

advancements in other fields such as manufacturing systems and materials have also been crucial

in the development of RP systems. Table (2.1) traces the historical development of relevant

technologies related to RP from the estimated date of inception

Table 1:Historical development of Rapid Prototyping and related technologies

Year of Inception Technology

1770 Mechanization

1946 First Computer

1952 First Numerical Control (NC) Machine Tool

1960 First Commercial Laser

1961 First Commercial Robot

1963 First Interactive Graphics System (CAD)

1988 First Commercial Rapid Prototyping System

1.1.Three Phases of Development Leading to Rapid Prototyping-

Prototyping or model making in the traditional sense is an age-oldpractice. The intention of

having a physical prototype is to realize the conceptualization of a design. Thus, a prototype is

usually required before the start of the full production of the product. The fabrication of

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prototypes is experimented in many forms — material removal, castings, moulds, joining with

adhesives etc. and with many material types — aluminum, zinc, urethanes, wood, etc.

Prototyping processes have gone through three phases of development, the last two of which

have emerged only in the last 20 years. Like the modeling process in computer graphics, the

prototyping of physical models is growing through its third phase. The three phases are described

as follows.

1. First Phase: Manual Prototyping-

Prototyping had began as early as humans began to develop tools to help them

live. However, prototyping as applied to products in what isconsidered to be the first phase of

prototype development began several centuries ago. In this early phase, prototypes typically are

not very sophisticated and fabrication of prototypes takes on average about four weeks,

depending on the level of complexity and representativeness. The techniques used in making

these prototypes tend to be craft-basedand are usually extremely labor intensive.

2. Second Phase: Soft or Virtual Prototyping-

As application of CAD/CAE/CAM become more widespread, the early1980s saw the evolution

of the second phase of prototyping — Soft orVirtual Prototyping. Virtual prototyping takes on a

new meaning as more computer tools become available — computer models can now be stressed,

tested, analyzed and modified as if they were physical prototypes. For example, analysis of stress

and strain can be accurately predicted on the product because of the ability to specify exact

material attributes and properties. With such tools on the computer, several iterations of designs

can be easily carried out by changing the parameters of the computer models.

Also, products and as such prototypes tend to become relatively more complex — about twice

the complexity as before. Correspondingly, the time required to make the physical model tends

toincrease tremendously to about that of 16 weeks as building of physical prototypes is still

dependent on craft-based methods though introductionof better precision machines like CNC

machines helps.

Even with the advent of Rapid Prototyping in the third phase,there is still strong support for

virtual prototyping. Lee [10] arguesthat there are still unavoidable limitations with rapid

prototyping. These include material limitations (either because of expense or through the use of

materials dissimilar to that of the intended part), the inability to perform endless what-if

scenarios and the likelihood that little or no reliable data can be gathered from the rapid prototype

to perform finite element analysis (FEA).

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3. Third Phase: Rapid Prototyping-

Rapid Prototyping of physical parts, or otherwise known as solidfreeform fabrication or desktop

manufacturing or layer manufacturing technology, represents the third phase in the evolution of

prototyping. The invention of this series of rapid prototyping methodologies is described as a

“watershed event” because of the tremendous time savings, especially for complicated models.

Though the parts (individual components) are relatively three times as complex as parts made in

1970s, the time required to make such a part now averages only three weeks. Since 1988, more

than twenty different rapid prototyping techniques have emerged.

References-

1. Jurgen Stampfl, Hao-Chi Liu, Seo Woo Nam, “Rapid Prototyping of Mesoscopic

Devices”, Proceedings Micromaterials 2000. Berlin, April 2000.

2. Karunakaran K P, “ Rapid Prototyping and Tooling”, Internal Circulation IIT Bombay.

3. Jurgen Stampfl, Hao-Chi Liu, Alexander Nickel., “ Rapid prototyping and manufacturing

by gelcasting of metallic and ceramic slurries”, Material Science and Engineering,

Elsevier.

4. Wheelwright, S.C. and Clark, K.B., Revolutionizing Product Development:Quantum

Leaps in Speed, Efficiency, and Quality, TheFree Press, New York, 1992.

5. Ulrich, K.T. and Eppinger, S.D., Product Design and Development,2nd edition, McGraw

Hill, Boston, 2000.

6. Hornby, A.S. and Wehmeier, S. (Editor), Oxford AdvancedLearner’s Dictionary of

Current English, 6th edition, Oxford UniversityPress, Oxford, 2000.

7. Koren, Y., Computer Control of Manufacturing Systems, McGrawHill, Singapore, 1983.

8. Hecht, J., The Laser Guidebook, 2nd edition, McGraw Hill, NewYork, 1992.

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17. TECHNIQUES OF COATINGS FOR CUTTING TOOLS

Yuvraj P. Ballal

Asst. Professor

1.INTRODUCTION:

The selection of cutting tool materials for a particular application is among the most important

factors in machining operations, as is the selection of mold and die material for forming and

shaping process. The cutting tool is subjected to high temperatures, high contact stress, and

rubbing along the tool chip interface and along the machined surface. Consequently, the cutting

tool material must possess the following characteristic like hot hardness, toughness and impact

strength, thermal shock resistance, wear resistance, and chemical stability and inertness. resource

on hand.

Coatings improve wear resistance, they increase tool life, they broaden the application range of a

given grade, and enable use at higher speeds. Commonly used coating materials are titanium

nitride (TiN), titanium carbide (TiC), Titanium carbonitride (TiCN) and aluminum oxide. These

coating, generally in the thickness range of 2 to 15μm, applied on cutting tools and inserts by two

techniques, chemical vapor deposition(CVD) and physical vapor deposition(PVD).

2 NEED OF TOOL COATING:

The required properties of cutting tool material at the surface and in the bulk are different and

conflicting. The surface of the tool needs to be hard, abrasion resistant, chemically inert, having

low thermal conductivity, and having low coefficient of friction. The bulk of the tool should be

tough, shock-resistant, having high thermal conductivity, and strong to resist high temperature

plastic deformation to retain form and geometry. This combination of properties can be achieved

by depositing a thin layer (typically 2-10 μm) of coating of suitable material over the surface of

the tool. Coatings act as diffusion barrier between the tool and the sliding chip, they increase

wear resistance of the tool, prevent chemical reactions between the tool and work material,

reduce built-up edge formation, decrease friction between the tool and chip, and prevent

deformation of the cutting edge due to excessive heating. Coated tools, therefore, can be used at

higher cutting velocities and provide longer tool lives than uncoated tools. Recent advances in

tool coating have made it an attractive choice for environment-friendly and cost effective dry

machining.

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3. TOOL COATING PROCESSES:

The processes used to add coatings to cutting tools-regardless of whether the substrate is HSS,

cemented carbide, cermet, ceramic, or a superhard material are chemical vapor deposition (CVD)

and physical vapor deposition (PVD).

3.1 CHEMICAL VAPOUR DEPOSITION COATING PROCESS:

In the CVD process, the tools are heated in a sealed reactor to about 1000ºC (1830ºF). Gaseous

hydrogen and volatile compounds supply the metallic and nonmetallic constituents of the coating

materials, which include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride

(TiCN), and aluminum oxide (Al2O3). CVD is also used to produce diamond thin films for

graphite and nonferrous cutting applications. Thickness of CVD coatings can range from ~5 to

20 µm.

The CVD process has significant advantages. It produces a chemical bond between the coating

and substrate, resulting in excellent adhesion. Also, the coating reaches all surfaces including

recessed areas and blind holes. Moreover, thick coatings can be deposited for heavy wear

applications [1].

3.2 PHYSICAL VAPOUR DEPOSITION COATING PROCESS:

PVD emerged in the 1980s as a viable process for applying hard coatings to cemented carbide

tools. In PVD, the coating is deposited in a vacuum. The metal species of the coating, obtained

via evaporation or sputtering, reacts with a gaseous species (nitrogen or ammonia, for example)

in the chamber and is deposited onto the substrate.

The chief difference between PVD and CVD is the former's relatively low processing

temperature--500ºC (930ºF).This lower processing temperature results in multiple benefits for

PVD coatings. For example, the grain structure of the coating is very fine. The result is a very

smooth, bright coating with a low coefficient of friction. And, PVD coatings are essentially free

of the thermal cracks that are common in CVD coatings. Another advantage of the PVD process

is the ability to coat tools with sharp edges and complex chip breaker geometries [2].

3.3 THERMOREACTIVE DIFFUSION COATING PROCESS:

Thermoreactive Diffusion (TD or TRD) is a high temperature coating process for producing

metal carbides (typically vanadium carbide) on the surface of a carbon-containing substrate. This

is a multi-stage coating process which utilizes a pre-heat cycle, a coating segment, ultra-sonic

cleaning, heat-treating, and post-coating polishing. The coating segment is performed in a molten

bath [typically consisting of a solute (Borax), a metal source, and a reducing agent]: carbide-

forming compounds in the bath react with carbon in the substrate and produce metal carbides on

the substrate surface. TD coatings exhibit a diffusion type bond, thereby providing superb

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adhesion between the metal carbide layer and the substrate. This bonding characteristic,

combined with the coating's high micro-hardness, provides excellent resistance to the types of

wear and galling often seen in many metal-forming processes.

4. TYPES 0F COATINGS:

Followig are the various types of coatings for various cutting tool inserts:

4.1 CONVENTIONAL HARD COATING:

The commonly used hard coatings for cutting tool applications include TiC, TiN, TiCN, Al2O3,

TiAlN, AlON, HfN etc. All these coatings exhibit very low wettability against ferrous materials.

TiC was the first hard material to be deposited over cemented carbide tool. Later, TiN proved to

be a better diffusion resistant material and therefore more suitable candidate for combating crater

wear. However, TiC is better in resisting flank wear owing to higher abrasive wear resistance.

TiCN offers some kind of balanced properties between TiC and TiN. Al2O3 provides chemically

stable layer between chip and tool especially at higher temperatures. TiAlN is relatively new

development to the family of hard coating and is of particular importance in metal cutting

because of its higher hardness (around 35 GPa) and oxidation resistance at high temperature. a-

C:H diamond like carbon (DLC) coating owing to its high hardness combined with superior anti-

sticking property has also recently found its application as a coating material for cutting tools[3].

4.2MULTILAYER COATINGS:

These coatings consist of alternate layers of different materials, deposited on top of another, and

also forming between themselves transitional layers. Such multilayer structure allows stronger

interface as well as dense and compact microstructure. Another significance of multilayer coating

architecture is the synergistic effects of different components of the coating system. One or more

of intermediate layer(s) ensure graduation of properties, and the outermost layer ensures good

tribological properties. Some of the examples of multilayer coatings are TiC/TiCN/TiN,

TiC/TiN/Al2O3, TiN/Al2O3/TiAlN, TiC/TiCN/TiN/Al2O3 (from interface to top layer) etc[3].

4.3 MULTICOMPONENT COATINGS:

In muticomponent metal nitride coatings the sublattice of one metallic element is partially filled

by one or more metallic elements, similar to substitutional type solutions. The properties of the

coating, therefore, can be tailored according to requirement in a specific application. Improved

film-substrate adhesion combined with high film hardness and better oxidation resistance at

elevated temperature is some of the important properties of multicomponent coatings that make

them suitable for metal cutting application. The examples of recently developed muticomponent

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coatings include TiAIN, TiSiN, TiCrN, TiZrN, TiVN, AlCrN, CrTiAlN, TiAlSiN, AlCrSiN,

TiAlCrYN etc[3].

4.4 SUPERLATTICE COATINGS:

Two coatings with the similar crystal structure and lattice constant are deposited alternately with

the period of different layers typically in the range of 5-15 nm. This results in a coating with

increased lattice strain and hardness. The typical examples of superlattice coatings include

TiN/CrN, CrN/NbN, TiN/NbN, TiN/AlN, TiN/VN, CrN/AlN etc [3].

4.5 SUPERHARD COATINGS:

Diamond and cBN are the most popular members of the family of superhard coatings used for

cutting tools. In addition to high hardness superhard materials usually possess some other

excellent properties such as high thermal conductivity, oxidation resistance, chemical stability

and low coefficient of friction. Diamond coatings with hardness in the range of 70-100 GPa are

commonly synthesised using hot filament CVD process. However, high solubility of carbon in

iron and other metals restrict the application of diamond coated tools to machining of aluminium

alloys, ceramics, glass, wood etc. The cBN coatings are typically deposited by ion assisted PVD

process. The challenge with PVD cBN films is to produce a thick, well adherent coating that can

survive in the adverse environment during machining. Some other examples of superhard

coatings include Si3N4, CNx, BCxN, Si-C-N, Ti-B-C-N possessing hardness in excess of 40

GPa. However, extensive research is being carried out to study the feasibility of their application

in metal cutting[3].

4.6 SOFT COATING:

Machining of sticky materials like alumnium and titanium alloys has been a major problem

particularly when good surface finish, high productivity, and long tool life are concerned. Even

use of conventional hard coatings like TiC, TiN, TiAlN etc. cannot yield satisfactory

performance. To overcome this difficulty a new family of coating has been conceptualised. They

are soft coating or solid lubricant coating like MoS2, WS2, graphite owing to the superior anti-

friction property compared to conventional hard coatings. However, some of the major

limitations of such coatings like poor abrasion, humidity and oxidation resistance restrict their

use mainly to low speed machining operation like milling and drilling [3].

4.7 COMPOSITE COATINGS:

In composite coating, a small amount of metal and/or compound is impregnated into the

monolayer homogeneous coating material with a view to either augment some of the existing

properties or to impart some additional chrematistics or both. For example, the strength, adhesion

and humidity resistance of pure MoS2 coating can be improved by incorporation of different

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metals like Au, Ti, Mo, W etc. into soft matrix of MoS2. Some of other examples of wear

resistance composite coatings include Al/Al2O3, Ti/TiN, Cr/TiN, Al/TiN etc. The composite

coating may or may not have layered structure depending on deposition condition and crystal

structure of individual materials[3].

5. FUNCTIONS OF COATING MATERIAL ON CUTTING TOOLS:

The most important mechanisms by which a coating can protect a substrate material are the

following though not limited to these areas specifically:-

a) The wear resistance of the coating itself should be superior to that of the substrate

b) The coating lowers the friction coefficient and thereby the contact temperature. A decrease in

friction also reduces the tendency for severe adhesive wear. The coating acts as a heat barrier

owing to the lower thermal conductivity compared with that of the substrate. Thus,

the proportion of frictional heat which dissipates into the substrate is reduced which, in turn,

lowers the substrate temperature.

c) The coating has lubricating properties because it can generate secondary layers in the wear

surface.

d) Elements of the coating material can diffuse into the substrate and thereby increase its wear

resistance long after the original coating-substrate interface has been penetrated [4].

e) Higher wear resistance, lower heat and lower cutting forces. So it will enabling them to

perform better at higher cutting conditions than uncoated cutting tools.

REFERENCES:

1. L.A. Dobrzanski, M.Staszuk ”Pvd and Cvd gradient coatings on sintered carbide and

sialon tool ceramics” Journals of achievements in materials and manufacturing

engineering, Dec 2010,vol 43,Issue2.

2. Dennis T quinto and F. Teeter “ challenging applications” Teeter marketing services llc

,Oct 2007,vol.59, no 10.

3. A. Soreng, ”Performance of multilayer coated tool in dry machining of AISI 316

austenitic stainless steel” NIT Rourkela, May2011,Pg.5-8.

4. Titus .B. Watmon and Anthony .C. Ijeh, “Coating Cutting Tools with Hard Substance

Lowers Friction Co-efficient and Improves Tool Life - A Review”, IMECS,March 2010.

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