by satyajit patil NIT Surat

1. SMART MATERIALS
PRESENTED BY – PATIL SATYAJIT SARJERAO
ADMISSION NUMBER – P15ME007
GUIDED BY – DR. B. M. SUTARIA

2. Contents
 Introduction
 Sensing and Actuating Properties of ‘Smart’ Materials
 Classification
 Piezoelectric materials
 Shape memory alloy
 Electrorheological fluid
 Magnetorheological fluid
 Electrostrictive materials
 Magnetostrictive materials
 Conclusion

3. Introduction
 Smart materials
Materials whose properties vary considerably in the presence of an external
stimulus are known as smart materials.
The stimuli like temperature, electric flow, magnetic flow, light,
mechanical can originate internally or externally.

4. Sensing and Actuating Properties of
‘Smart’ Materials
 Smart materials are not only capable of sensing changes in their environment; they
are also able to take action correspondingly. Therefore, it can be said that they
possess both sensory, as well as actuatory properties

5. Classification
 Shape-memory alloys
 Piezoelectric materials
 Electro strictive and magneto strictive materials
 Field responsive composites
➢ Electrorheological fluids
➢ Magnetorheological fluids

6. Piezoelectric materials
 Piezoelectric materials produce a voltage when stress is applied. Since this
effect also applies in the reverse manner.
Piezo electric effect
The piezoelectric effect is based on the elastic deformation and orientation
of electric dipoles in a crystal structure when subjected to an electric field.
The application of an external mechanical force deforms and displaces the
electric dipoles and the charge distribution is no longer symmetric. In this way, a
charge is generated at the surface of the crystal
Conversely, the application of a high electric field causes deformation and forces
the randomly oriented micro-dipoles into alignment.
Example - gallium phosphate, quartz, tourmaline

7. Advantages
 Unaffected by external magnetic field
 Reversible (use as sensor or actuator)
 Fast response, thus very fast actuation
 Resistive to environment (humidity ,
temperature )
 High position accuracy (small displacement
with applied voltage )
 High generation of force per unit of
Disadvantages
 Brittle in tension
 At certain temperature all piezoelectric
properties are lost
 Power consumption increases linearly with
frequency and actuator capacitance
 The typical operating limit is between
500V/mm and 1000V/mm for continuous
application.
 Small displacement
 Possible health risk of lead in piezoelectric
ceramics.

8. Applications of piezoelectric material
 Automotive- Air bag sensor, tyre pressure sensor
 Computer- Touchpad , inkjet printers
 Consumer- lighter
 Medical- Electronic Stethoscopes, Patient Monitors, Cardiac Pacemakers,
 Surface roughness measurement
lighter

11. Shape Memory Alloys
 A group of metallic materials that can return to some
previously defined shape or size when subjected to the
appropriate thermal procedure.
Shape memory effect
Shape memory effect is the result of a thermo-elastic
martensite transformation.
The deformation can be recovered by heating the material
to temperatures above the transformation temperature.
Type
1. NITINOL (-100OC to 100OC)
2. Copper-Zinc alloy (-180OCto 200OC)

12.  One-way shape memory effect  Two-way shape memory effect

13. Advantages
 Good Mechanical Properties- strength,
resistance to corrosion, fatigue
 Large recovery force
 Few mechanical parts, reducing overall
system complexity
 Variable shapes
 Function in water and in other liquids, in a
vacuum, and in most hazardous
environment
 Bio-compatibility
Disadvantages
 Limited range of transformation
temperatures
 Hysteresis
 Heat dissipation
 Duration and stability of the SME uncertain,
because research in this area is relative
young.
 Relatively low velocity
 Actuation requires heating and cooling

14. Application of shape memory alloy
 Bone facture recovery
 Reinforcement for Arteries and Veins
 Dentistry – orthodontic wire
 Anti-scalding protection
 Fire security and Protection systems

16. Electrorheological Fluids
 The resistance to flow increases with increasing electric field. This is caused by an
increase of the viscosity of the fluid
Working
Electrorheological fluids are dispersions of small dielectric particles, which can be
solid or liquid, suspended in a non-conducting carrier liquid.
The electric field induces dipoles in the dielectric particles and these particles then
will start to aggregate. They will start to form fibrous structures(chain-like) between
the electrodes These chain-like structures restrict the motion of the fluid

17. The components of an ER fluid
 Continuous phase (carrier liquid)
Silicone oil, vegetable oil, mineral oil, paraffin, kerosene.
 Dispersed phase (Particles)
Inorganic oxide materials, Non-oxide inorganic, Organic and polymeric
 Additives
Polar liquids - Alcohol, dimethylamine, acetamide,

18. Advantages
 ER fluids a reversible and controllable
change in their rheological properties
when subjected to an electric field.
 Electric fields are easy to supply.
 Suitable for dynamic applications
 ER fluids show very low abrasiveness
Disadvantages
 The relatively low attainable yield
stress.
 ER fluids are voltage driven. They
require large voltages (some kV) at
a low current (few mA).
 ER fluids are very sensitive to
impurities or contaminants.

19. Magnetorheological Fluids
When subjected to a magnetic field, MR fluids undergo a change in their viscosity
and can change from a liquid state with a relatively low viscosity, like motor oils, to
an almost solid state.
Working
Magnetorheological fluids are typically colloidal suspensions consisting of highly
polarizable magnetic particles. When the MR fluid is subjected to a magnetic field,
the particles become magnetized and they start to behave like tiny magnets. This
causes the particles to aggregate and form chain-like structures within the carrier
liquid, These chain-like structures restrict the motion of the fluid

20. The components of an MR fluid
 Continuous phase (carrier liquid)
silicone oils, synthetic oils, mineral oils, petroleum based oils and combinations
of several types of oil.
 Dispersed phase (Particles)
carbonyl, electrolyte iron powder
 Additives
Anti-friction and anti- abrasion/erosion compounds, grease , metallic soaps

21. Advantages
 MR fluids are current driven. For the
control of the field coil voltages below
10 V and currents below 2 A can be
sufficient to operate the device
 The response time of MR based
is estimated to be around 15-25 ms
 MR fluids are able to attain high shear
stresses
 MR fluids are not very sensitive to
contaminants and impurities
Disadvantages
 Magnetic fields are not easy to supply
and use.
 higher risk of sedimentation
 high density
 ‘off’-state viscosity of MR fluids is
relatively high.

22. Applications of MR fluid & ER fluid
 Control of flow of liquid through narrow channels
 Friction devices such as clutches, brakes
 Clamping and positioning devices in machining of materials
 Damper in automobile
 Adjustable real-time controlled shock absorbers for automobiles
 Magnetorheological fluid polishing tools

24. Electrostrictive materials
 Dimensional change of a material under the influence
of applied electric field
 The main difference between electrostrictive and
piezoelectric materials is that the first doesn’t show
spontaneous polarization. The lack of a spontaneous
polarization means that electrostrictive materials
display little or no hysteresis, even at very high
frequencies
Working principle
 Upon subjection to an electric field the positively and
negatively charged ions separate, thereby changing
the dimensions of the cell and resulting in an
expansion
 Stain always positive

25. Advantages
 Very high sensitivity and accuracy
 Very low hysteresis and creep
 Their capacity to exert high
pressures.
 More precise transfer ratio between
the applied voltage and dilatation
Disadvantages
 Very low temperature stability
 The electrical capacitance is 4-5
times as high as piezoelectric
materials
 Impossible to generate negative
strain

26. Magnetostrictive Materials
 Upon subjection to a magnetic field. This leads to Joules effect
 This ‘Joule’ effect is responsible for the expansion (positive magnetostriction) or
the contraction (negative magnetostriction) of the material when a magnetic field
is applied.
Working Principle
 When a magnetic is applied to a Magnetostrictive material, its magnetic domains
will rotate until they are aligned with the applied field.
 This alignment causes the material to change its shape, while its volume stays
approximately the same.
Example- Terfenol-D

27. Advantages
 High power density (two to three
orders higher than piezoelectric
materials)
 No need for direct physical
contact to the structural surface
 Low non-linearity
Disadvantages
 The use of magnetic field
 Lower efficiency of energy
conversion of the magneto strictive
method at higher frequencies

28. Application of magneto strictive and electro strictive materials
 Sonar transducers
 Reaction mass actuator
 electro-hydraulic actuator
 Valve

29. Reaction mass actuator
Sonar transducers valves
Electro-hydraulic actuator

30. Case study
 Behaviour of Magnetorheological Fluids with Different Material Types and
Magnetic Field Strength
In this study the experiments are conducted to evaluate the friction property under
reciprocating motion by changing the types of MR fluid and the strength of a
magnetic field. The material of aluminium, brass, and steel are chosen for specimen

31. Friction coefficients change for different materials

32. Friction coefficients change with respect to types of MR fluid and the
strength of magnetic field a)122EG b) 132DG c)140CG

33. Conclusion
 Smart materials have all the possible potentials to improve existing technology
and add new functionality to product.
 Smart materials used in almost every field of Engineering and Medical field.
 Smart materials have shown impressive characteristics and with further Research
and Development it will be superior to use smart materials in various applications
without fail.

34. THANK YOU