A Seminar Report

On

SMART MATERIALS

In partial fullfilment of the requirements for the award of the Degree

Of

MASTER OF TECHNOLOGY

IN

MECHANICAL ENGINEERING

Submitted by

Pardeep Dahiya

Roll No. 13001504023

Department of Mechanical Engineering

Deenbandhu Chhotu Ram University of Science and Technology

Murthal, Sonepat

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INDEX :

1. INTRODUCTION

2. WHAT ARE THE SMART MATERIALS?

2.1 OVERVIEW OF SMART MATERIALS2.2 ADVANTAGES OF SMART MATERIALS2.3 LIMITATIONS OF SMART MATERIALS2.4 APPLICATIONS OF SMART MATERIALS

3. VARIOUS SMART MATERIALS3.1 PIEZOELECTRIC MATERIALS3.2 ELECTRO-RHEOSTATIC & MAGNETO-RHEOSTATIC

MATERIALS3.3 SHAPE MEMORY ALLOYS(SMA)3.4 KEN MATERIALS3.5 BIOMIMETICS3.6 DUMB MATERIALS

4. CONCLUSION

5. FUTURE OF SMART MATERIALS

6. REFERENCES

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1. INTRODUCTION

Smart materials are materials that have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as stress, temperature, moisture, pH, electric or magnetic fields.

Such materials have the ability to change shape or size simply by adding a little bit of heat, or to change from a liquid to a solid almost constantly when near a magnet; these materials are called smart materials.

There are a number of types of smart material, some of which are already common. Some examples are as following:

• Piezoelectric materials are materials that produce a voltage when stress is applied. Since this effect also applies in the reverse manner, a voltage across the sample will produce stress within the sample. Suitably designed structures made from these materials can therefore be made that bend, expand or contract when a voltage is applied.

• Shape memory alloys and shape memory polymers are Thermoresponsive materials where deformation can be induced and recovered through temperature changes.

• Magnetic shape memory alloys are materials that change their shape in response to a significant change in the magnetic field.

• pH-sensitive polymers are materials which swell/collapse when the pH of the surrounding media changes.

• Temperature-responsive polymers are materials which undergo changes upon temperature.

• Holochromic materials are commonly materials that change their colour as a result of changing acidity. One suggested application is for paints that can change colour to indicate corrosion in the metal underneath them.

• Chromogenic systems change colour in response to electrical, optical or thermal changes. These include electrochromic materials, which change their colour or opacity on the application of a voltage (e.g. liquid crystal displays), thermochromic materials change in color depending on their temperature, and photochromic materials, which change colour in response to light - for example, light sensitive sunglasses that darken when exposed to bright sunlight.

• Non-Newtonian fluid is a liquid which changes its viscosity in response to an applied shear rate. In other words the liquid will change its viscosity in response to some sort of force or pressure. One good example of this is Oobleck, a fluid that seems to temporarily turn into a solid when a force is applied quickly. Another good example is Custard, as long as it is starch based.

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2. WHAT ARE SMART MATERIALS?

“Smartness” of a material is characterized by self-adaptability, self sensing memory and decision making. Smart materials are the materials that respond with shape or other property change upon application of externally applied driving forces (electrical, magnetic and thermal). In other words, smart materials refer to materials that can undergo controlled transformations through physical interactions and are structured with multi-functionality. They have they are able to respond to slight variation in temperature, moisture, pH, electric or magnetic fields by changing their appearance, state and properties. They are exemplified as boon in tackling the problem of deteriorating civil infrastructure and they had influenced the life cost of these structures by reducing the upfront construction cost as they allow reduced safety factors in initial design.

2.1OVERVIEW OF SMART MATERIALS:

• Smart materials are the materials which have certain characteristics by which they have special position in our life. We can not think about these development and growth.

• Smart materials sense and respond to their environment and application in areas as diverse as health, defense, packaging etc.

• Smart materials can think and do amazing things. They are very quick respond to the environment around it. However it has different applications, it has some advantages and limitations.

2.2ADVANTAGES OF SMART MATERIALS:

• High energy density.• Excellent bandwidth.• Novel function such as huge volume change as a function of temperature

exhibited by the smart gels.• Some smart materials are self repaired materials as the materials can repaired

itself if damaged occurs.• Smart materials have better durability and reliability.• Smart materials reduces the production cost.• Smart materials get smarter with ability to better control of shape & size.• Smart materials can easily cooled with nano fluids.• Smart materials extensively used in Textile Industries changes the face of this

industries.• Smart materials reduces the weight of component used in the mechanical &

electrical industries.• The Structural Health Monitoring of smart materials can easily & perfectly

done.

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• Smart materials are gives excellent results in Communication Technology & Information Technology’

2.3 LIMITATIONS OF SMART MATERIALS:

• Smart materials are very expensive.• They are not easily available in market.• They are very sensible so they need proper care while storage it.• Smart materials needs proper skill to recognize it among other materials.

2.4APPLICATIONS OF SMART MATERIALS:

• In the Fast response valve.• High power density hydraulic pumps.• Active bearings for reduction of machine noise.• In the manufacturing of footwear.• Sports equipment & precision machining.• Vibration & acoustic sensors.• In the dampers.• There are many possibilities for such materials and structures in the man-

made world.• Engineering structures could operate at the very limit of their performance

envelopes and to their structural limits without fear of exceeding either.• The different fields have various applications of smart materials. The

different fields are listed below.1. Application of Smart materials in Medical Technology.

2. Application of Smart materials in Automobiles Engineering.

3. Application of Smart materials in Mechanical Engineering.

4. Application of Smart materials in Civil Engineering.

5. Application of Smart materials in Aerospace.

6. Application of Smart materials in Mechatronics.

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3. VARIOUS SMART MATERIALS:

3.1 Piezoelectric materials:

Fig. 3.1 shows Piezoelectric materials

• Piezoelectric materials have two unique properties which are interrelated.

• When a piezoelectric deformed, it gives off a small but measurable electrical discharge. Alternately, when an electrical current is passed through a piezoelectric material it experiences a significant increase in size.

• The piezoelectric effect describes the relation between a mechanical stress and an electrical voltage in solids.

• It is reversible: an applied mechanical stress will generate a voltage and applied voltage change the shape of solid by a small amount ( up to 4% ).

• Piezoelectric materials are widely used as sensors in different environments.

• They are often used to measure fluid density, fluid viscosity, fluid composition and the force of the impact.

• The example of piezoelectric material is the safety air bags in the car.

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3.2 Electro-rheostatic and Magneto-rheostatic Materials:

• Electro-rheostatic (ER) and Magneto-rheostatic (MR) materials are fluids, which can experience a dramatic change in their viscosity. These fluids can change from a thick fluid (similar to motor oil) to nearly a solid substance within the span of a millisecond when exposed to a magnetic or electric field; The effect can be completely reversed just as quickly when field removed.

• MR fluids experience a viscosity change when exposed to magnetic field, while ER fluids experience similar changes in an electric field.

Fig 3.2. The MR fluid is liquid as shown on the left, when no magnetic field is present, but turns solid immediately after being placed in a magnetic field on the right.

• MR fluids are being developed for use in car shocks, damping, washing machine vibration, prosthetic limbs, exercise equipment and surface polishing of machine parts.

• ER fluids have mainly been developed for use in clutches and valves as well as engine mounts design to reduce noise and vibration in vehicles.

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3.3Shape memory alloys:

• Shape memory alloys (SMA’s) are metals, which exhibit two very unique properties, pseudo elasticity and the shape memory effect.

• These two properties are related to solid phase change in which only molecular rearrangement will be there, means substance will remain solid.

• The two phases which occur in shape memory alloys, are Martensite and Austenite.

• The temperatures at which each of these phases begin and finish forming are represented by the following variables: Ms, Mf, As, Af.

• The amount of loading placed on a piece of shape memory alloy increases the values of these four variables as shown in Figure.

• The initial values of these four variables are also dramatically affected by the composition of the wire (i.e. what amounts of each element are present).

Fig 3.3(a) shows a temperature – load diagram for Martensite & Austenite

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Fig 3.3(b) scopic Diagram of the Shape Memory Effect

Fig 3.3(c) Shape memory polymers.

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Fig 3.3(d) Shape memory wire.

3.4 Ken Materials:• ‘Mechatronics’ smart structures have demonstrated the capability of this

technology, but raise the important issue of the complexity of the resulting

system.

• These smart structures contain a multitude of different materials, and in the

case of sensual structures will generate large amounts of data.

• This increase in complexity has been described by Hiroaki Yanagida as the

‘spaghetti syndrome’, and has led to the proposal for an alternative type of

smart structure based on the concept of ken materials (the Chinese characters

meaning wisdom, structure, monitoring, integration and benignity being

pronounced ken in the Japanese language). Such structures would move

functional integration into the constituent engineering materials themselves.

• Few practical examples of ken materials exist at present, although a structural

composite based on this concept has been developed in Japan.

• This is a carbon and glass fibre reinforced concrete which is able to monitor

concrete structures using only the structural reinforcing fibres, thus reducing

the complexity of the system.

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Fig 3.4 Structure of ken materials

3.5. Biomimetics:

• ‘Dumb’ materials and structures contrast sharply with the natural world where animals and plants have the clear ability to adapt to their environment in real time.

• The field of biomimetics, which looks at the extraction of engineering design concepts from biological materials and structures, has much to teach us on the design of future manmade materials.

• The process of balance is a truly ‘smart’ or intelligent response, allowing, in engineering terms, a flexible structure to adapt its form in real time to minimise the effects of an external force, thus avoiding catastrophic collapse.

• The natural world is full of similar properties including the ability of plants to adapt their shape in real time (for example, to allow leaf surfaces to follow the direction of sunlight), limping (essentially a real time change in the load path through the structure to avoid overload of a damaged region), reflex to heat and pain. The materials and structures involved in natural systems have the capability to sense their environment, process this data, and respond.

• They are truly ‘smart’ or intelligent, integrating information technology with structural engineering and actuation or locomotion.

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Fig 3.5 microstructure of Biomimetics.

3.6 Dumb Materials:

• Most familiar engineering materials and structures until recently have been ‘dumb’. They have been preprocessed and/or designed to offer only a limited set of responses to external stimuli.

• Such responses are usually non-optimal for any single set of conditions, but ‘optimized’ to best fulfil the range of scenarios to which a material or structure may be exposed.

• For example, the wings of an aircraft should be optimised for take-off and landing, fast and slow cruise etc. However, despite the partial tailoring of these structures by the use of additional lift surface, which we see deployed as each passenger aircraft approaches an airport, such engineering components are not fully optimized for any single set of flight conditions.

• Similarly, advanced composites such as glass and carbon fibre reinforced plastics, which are often thought to be the most flexible engineering materials since their properties (including strength and stiffness) can be tailored to suit the requirements of their end application, can only be tailored to a single combination of properties.

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4. CONCLUSION

Smart materials are able to sense and respond to environment around them.

• They have the potential to improve existing technology and add new functionality to products.

• They have applications in a wide variety of areas and they have an important role in waste reduction.

• They have a capability to work in multifunctional way.

• Although smart materials and systems have been researched for decades, commercial exploitation has been slow. The interdisciplinary nature of the subject and divide between scientist and designers has slow this exploitation.

Thus we conclude that there is an important role of smart materials in our life.

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5. THE FUTURE

• The development of true smart materials at the atomic scale is still some way off, although the enabling technologies are under development.

• These require novel aspects of nanotechnology (technologies associated with materials and processes at the nanometer scale, 10-9m) and the newly developing science of shape chemistry.

• Materials and structures which respond to their environment, including their human owners, is a somewhat alien concept.

• It is therefore not only important that the technological and financial implications of these materials and Worldwide, considerable effort is being deployed to develop smart materials and structures.

• The technological benefits of such systems have begun to be identified and, demonstrators are under construction for a wide range of applications from space and aerospace, to civil engineering and domestic products.

• In many of these applications, the cost benefit analyses of such systems have yet to be fully demonstrated.

• The Office of Science and Technology’s Foresight Programmed has recognized these systems as a strategic technology for the future, having considerable potential for wealth creation through the development of hitherto unknown products, and performance enhancement of existing products in a broad range of industrial sectors.

• The concept of engineering structures are addressed, but also issues associated with public understanding and acceptance.

• The core of Yanagida’s philosophy of ken materials is such a concept. This is ‘techno-democracy’ where the general public understand and ‘own’ the technology.

• Techno-democracy can come about only through education and exposure of the general public to these technologies.

• However, such general acceptance of smart materials and structures may in fact be more difficult than some of the technological hurdles associated with their development.

• Now in future new ECO-FRIENDLY smart materials are developed for reducing the harmful effect of some smart materials.

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6. REFERENCES Kumar Dr. Rakesh and Kumar Dr. Ram: ICI journal; pp. 15-18; April- June 2005. http://dbtindia.nic.in http://www.cs.ualberta.ca http://www.answers .com

http://structure.nuae.nagoya-u.ac.jp • Primary author: Cliff Friend Source: Abstracted from Materials World, vol. 4, pp. 16-18, 1996 “Smart materials: the emerging technology”.

• http://amptial.alionscience.com/products and services/product.html

• http://smart-material.com

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