Internship Report Khurram

7/23/2019 Internship Report Khurram

1/11

Internship report

(13-06-2012 to 09-07-2012)

Report Submitted By,

Khurram Suleman

Reg. # 2009-NUST-BE-Mech-228

Degree 31

Mechanical Engineering Department

NUST College of EME


2/11

Table of Contents

1. Ultrasonic C-Scan .......................................................................................... 3

Introduction: ............................................................................................................................................. 3

Test performance: ..................................................................................................................................... 3

2. Scanning Electron Microscopy (SEM)............................................................. 4

Introduction: ............................................................................................................................................. 4


3. Volume fraction/Density measurement ........................................................ 6

Introduction: ............................................................................................................................................. 6


4. Drop weight impact and compression after impact tests .............................. 7

Introduction: ............................................................................................................................................. 7


5. Composite lay-up and fibre placements ........................................................ 8

Introduction: ............................................................................................................................................. 8

Pre-form Making: ...................................................................................................................................... 9

Vacuum Bagging:....................................................................................................................................... 9

6. Laser Processing .......................................................................................... 10

Laser metal deposition:........................................................................................................................... 10

Laser drilling: ........................................................................................................................................... 10

References ........................................................................................................ 11


3/11

1. Ultrasonic C-ScanTest performed by: Dr. Rizwan Saeed Choudhry

Sample: Glass with Epoxy

Introduction:Ultrasonic C-Scan is a non destructive testing method in which 2 transducers are used to

generate and sense ultrasonic signals passed through specimen. This scan is used to find out spatial

position, depth and size of defects in composite plates. The main specifications of this equipment are as

follows[1]

:

Equipment Type Fixed/Portable Maximum Size orWeight of Sample

Main Uses

Midas Water JetC-Scan

ThroughTransmissionUltrasonic

Fixed 2m x 2m flat orslightly curved panels

Spatial position, depth andsize of defects in compositeplates

It uses two water jets to act as a medium for the propagation of ultrasonic signals. Using the

variation of speed of sound with density of medium, the defected portion of material can be found.

Test performance:

Before the start of test it is required to align the two water jets so that signal will not distort.

The probes used for the test ranges from 0.5 to 15 MHz. For that particular test probe was of 5 MHz.

now to start the test, jets were turned on, the orientation and flow rate of water was adjusted manually.

After adjusting the water jets the sample was fixed in fixtures as shown in following figure.

The position of water jets at bottom left and top right position was then set. The scanner has two

reference axis of translation. The horizontal axis is named to be x-axis and vertical axis is named to be z-


4/11

axis. The speed in x direction was set to be 100 mm/s and index (z step) was set to be 200 m. The top

right and bottom left positions of the probe in terms of x and z coordinates are as follows:

Digitize bottom left Digitize top right

x 1126.2 1417.3

z -171.10 135.5

After setting all the options and controls, the scan was started. The scan initiated from bottom

left corner and moves towards right, covered 200 m upward and completed the scan. The following left

figure is during the scan and its output is shown in the right one. The green area in the right figure shows

absence of any material (i-e only air).

2. Scanning Electron Microscopy (SEM)Mentor: Erdem Selver

Research topic: Damage tolerance in textile composites

Sample: E-Glass/Polypropylene + epoxy (90-0)

Glass + Epoxy

Introduction:

Scanning electron microscope is a type of electron microscope that captureimages with electron beam by moving line by line (raster scan) of

specimen. The equipment used was S-3000 N Hitachi SEM as shown in

adjacent figure. The sample used for SEM is a hybrid material in which

reinforcement is composed of E-Glass and Polypropylene and matrix was

epoxy. The other sample was E-Glass with epoxy. The SEM is conducted for

impacted sample as shown below at left (white is Glass with Epoxy having


5/11

20 Joule impact, black is glass/PP with epoxy). To prepare the specimen for test the sample is cut at the

middle of impact and then surrounded by resin that act as a permanent holder for specimen as show in

right figure. This specimen is polished and cleaned before inserting it into SEM.

Test performance:

The specimen is inserted into its position as shown in

adjacent figure and the door is the closed. Vacuum button is then

pushed to evacuate internally. Now after some time the images

appeared at interface. The adjustment of this SEM was manuallyoperated for position as well as magnification. The magnification can

go up to thousands and 50 is the least. The figure below is showing

the image at 50x magnification. It shows both the warp and weft

direction of yarns. Black are the polypropylene and white are of glass.

The rest black portion is epoxy resin forming the matrix.


6/11

3. Volume fraction/Density measurementMentor: Erdem Selver

Introduction:

The volume fraction of sample was found by first measuring its density and then by finding out

the weights before and after burning of sample in furnace. The apparatus used for density and weighing,

uses principal of buoyancy in water and then calculates the density

by the formula:

=

Where in the above equation is the density of sample, is the

weight of sample in air, is the weight of sample in water and

is the density of distilled water which is known.

There were 3 samples of commingled yarns of E-glass and

polypropylene as shown in adjacent figure.

Test performance:

As shown in above formula for density, the sample was weighed in

air and then in water (shown in adjacent figures). The software then

calculates density and output the calculation in set units. The samples

were then placed in furnace up to 600 C for one and half hour to burn

polypropylene yarns. It was then weighed again to find out weight of

polypropylene fiber yarns and hence to calculate volume fraction. The

individual densities of E-glass and polypropylene are known. Fewmeasurements done are tabulated below:

In the above calculations densities of E-Glass and polypropylene was taken

to be 2.56 g/cm3and 0.9 g/cm3respectively.

Sample

No.

Density

g/cm3

Weight

of

Sample

g

Weight

of PP

g

Mass

fraction

Volume

fraction

E-

GlassPP

E-

GlassPP

1 2.098 236.19 29.64 0.875 0.125 0.716 0.291

2 2.143 176.07 17.85 0.899 0.101 0.752 0.241


7/11

4. Drop weight impact and compression after impact testsMentor: Erdem Selver/Dwi

Introduction:

To find out damage tolerance of hybrid composite, drop weight impact testing is done. The equipment

used for the test has following main specifications [2].

This equipment has closed chamber by which controlled environmental

conditions can be applied. Impact is made by dropping known weight

through height. A metal cylinder, with hemispherical shaped top carries the

weight and produces impact on specimen fixed in a fixture.

After the impact at the centre of samples, these samples were tested in

compression test. The equipment used for compression test is shown in

adjacent figure.

Test performance:

For impact the samples were fixed firmly in a fixture and then placed inside the chamber of impact

testing machine. 5 kg weight is used to make impact. Height, temperature and required impact energy is

set through software interface. Impacts of 15 joule and 20 joule were made. The settings for 20 joule

impact are as follows:

Energy Height Mass Temperature

20 Joule 599.7 mm 5 kg 26 `C

One of the samples having E-glass reinforcement and epoxy matrix after impact is

shown in adjacent figure.

EquipmentName

MaximumGravityModeVelocity(m/s)

MaximumSpringAssistedVelocity(m/s)

SimulatedDrop HeightRange (m)

WeightRange(kg)

ImpactEnergyRange(J)

Relevant Standards Projectile

InstronCEAST9350

0.77 24 0.03 - 29.4 2.0 - 70 0.59 -1800

- ISO 3127, 6603, 7765,11343, 8256 - DIN 53373-PR EN 6038- ASTMD2444, D3763, D5268,D7136, D7192- BoeingBSS 7260 Airbus

AITM1.0010,1-0057-SACMA SRM 2R-94

16mmhemisphericaltup insert


8/11

After impact, compression test were performed for both impacted and non impacted samples of glass

with epoxy composites. The samples were fixed in fixture as shown in following figures. The fixture was

then place in Instron testing machine.

The zero position of machine was manually adjusted so that loading is in between 0.0150-0.0200 KN.

Thickness, height and width of samples was entered. The machine was started and continued to

increase load till the breakage of samples or the declination of load displacement curve. The impacted

samples got fracture in their middle while non impacted samples did not show any fix location offracture and got fracture at weak portion of composite. The fractured samples after compression are

shown in following figures (impacted on left, non-impacted on right).

5. Composite lay-up and fibre placementsMentor Erdem Selver

Introduction:

Among many different types of composite layup, one is making pre forms of

fibers yarns and then infusing it by resin. The equipment used here is a robotic

four-axis tow placement machine, shown in adjacent figure. Tow can be


9/11

placed in any orientation i-e, 0, 45, 90. The same machine can be used for tufting once the pre form is

ready.

Pre-form Making:

First the foam was placed below the pins so that threads of tufting can be held tightly once fiber

layers are set up. The foam was then covered by peel ply to remove the fiber layers. The pins were thenfastened by nuts. The program was then fed and run on the computer to start the placement of tows

and making of layers. Glass fiber was used to place 14 layers at 0 and 90 degree angle.

The above figures show the step by step process of tow placement

from left to right. After forming 14 layers of fiber, tufting was done.

5 lines of threads making loops on each side were made. The lower

portion of whole layup is shown in adjacent figure where black

threads making loops of tufting are quite visible.

Vacuum Bagging:Once tufting is done, its noweasy to remove whole layup from metal base and pins. First the flat mold

is cleaned. Teflon sheet is place and tapped to remove the composite after curing. Top and bottom

mesh was placed and taped. Then whole layup is removed from its panel and placed above the bottom

mesh.

Extra fibers were removed. One peel ply is placed at the top below the upper mesh. Finally the vacuum

bag was made with the help of sealing tape. It was then vacuumed and checked for half an hour with

gauge to ensure no leakage of air from the bag. This whole process is shown in above figures step by

step from left to right.


10/11

6. Laser ProcessingDemonstration by: Col. Khalid

Laser metal deposition:

Laser metal deposition is the additive manufacturing method in

which metal wire or metal powder is melt to form a desired shape.

For melting of metals, LASER is used. A solid substrate of the same

material is used as base. A metal powder is fed by mixing it with

argon gas because of its inert behavior. The powder metal feeder is

shown in adjacent figure.

The metal powder from the feeder comes into deposition chamber,

where it melts by class 4 diode LASER. The internal view of chamber

is shown in left figure. The powder and LASER beam are coaxial.Before metal deposition the substrate is cleaned by sand blasting

process.

Laser drilling:

A very small diameter holes can be drilled with the help of LASER. The equipment and holes produced by

it is shown in following figures.


11/11

References

[1]http://www.nccef.co.uk/Facilities/Non-DestructiveTesting.aspx

[2]

http://www.nccef.co.uk/Facilities/MechanicalandImpactTesting.aspx
http://www.nccef.co.uk/Facilities/Non-DestructiveTesting.aspxhttp://www.nccef.co.uk/Facilities/MechanicalandImpactTesting.aspxhttp://www.nccef.co.uk/Facilities/MechanicalandImpactTesting.aspxhttp://www.nccef.co.uk/Facilities/Non-DestructiveTesting.aspx

Internship Report Khurram

Documents

Transcript of Internship Report Khurram