WELCOME

TECHNICAL SEMINAR ON

“SMART MATERIALS”

INTRODUCTION

HISTORY OF SHAPE MEMORY ALLOYS:

The first reported step towards discovery of shape memory effect were taken in 1930’s according to Otsuka and Wayman In a silver-cadmium alloy.Shape memory polymers have also been developed and become commercially available in late 1990’s.

INTRODUCTION:Shape memory alloys or SMA's are metals that exhibit

shape memory properties.It allows materials possessing shape memory properties to return to their original shape after having suffered some form of deformation after they are heated to temperatures above their transformation temperature.

What are Smart Materials?

Senses a stimulus (eyes). Takes an intelligent decision (brain). Through electronic feedback it takes

corrective/preventive measures to avoid catastrophic situations (arm).

DEFINITION OF SMART MATERIALS:

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.

TYPES OF SMART MATERIALS

1. Shape memory alloys2. Piezoelectric materials3. Magnetostrictive materials4. Active fluids5. Ph and temperature sensitive polymers.

1) SHAPE MEMORY EFFECTS

TWO TYPES OF COMMON EFFECTS ARE:1) ONE WAY EFFECT2) TWO WAY EFFECT

ONE WAY EFFECT:When a shape memory

alloy is in its cold state, the metal can be bent or stretched and will hold those shapes until heated above transient temperature. Upon heating the shape changes to its original.

TWO WAY EFFECT:A Material That Shows

Shape Memory Effect During Both Heating And Cooling Is Called “Two Way Shape Memory”

a) INITIAL STATEb) DEFORMED SHAPEc) HEATINGd) BACK TO ORIGINAL SHAPE

2) PIEZOELECTRIC MATERIALS

Expand and contract with the application of voltage.

Piezoceramics are the most widely used smart material.

Applications Ink Jet Printers. Medical Diagnostics. High frequency stereo-

speakers. Computer Keyboards. Microphones.

3) MAGNETOSTRICTIVE MATERIALS

Expand and contract with the application of magnetic fields.

Applications High-power sonar transducers. Motors. Hydraulic actuators.

4) ACTIVE FLUIDS

Respond to an electric or a magnetic field with a change in viscosity.

Applications Tunable dampers. Vibration-isolation systems. Clutches. Brakes. Resistance Controls

5) pH AND TEMPERATURE SENSITIVE POLYMERS

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.

Used as surface modifiers , drug delivery.

APPLICATIONS :

Activate control inceptors using smart material motion control.

Remove toxic pollutant from water. Advanced liquid crystal display. Artificial muscles. Hydraulic fitting. To determine the defects in buildings and

bridges. To find stealth in aeroplanes and

submarines.

ADVANTAGES :

BIO-COMPATIBILITY STRONG , CORROSIVE RESISTANT PRODUCES VERY LARGE RECOVERY

STRESSES MATERIAL IS DUCTILE VERY EFFECTIVE FOR LOW FREQUENCY

VIBRATIONS

DISADVANTAGES :

o Expensive to manufacture.o Slow reaction time.o Non linear thermo-mechanical behavior

can limit the accuracy.o Low energy efficiency conversion.

CONCLUSION:

“ Smart materials” are just starting to emerge from the laboratory but soon you can expect to find them in everything from laptops to concrete bridges.

THANK YOU

PRESENTED BY :ANANTH KR SHIVARAJ N