Smart Materials and their Applications in Engineering

Dr. Mohammad Tawfik

Smart Material: What?

• Controlled change in properties

– Change in mechanical properties (MR fluids, SMA)

– Change in geometry (Piezoelectric, SMA)

• Energy Converters!

– Mechanical Electrical (Piezoelectric)

– Heat Mechanical (SMA)

– Mechanical Heat (Viscoelastic)

– Etc…

Smart Materials: Why?

• Vibration Damping

• Shape Control

• Noise Reduction

• Vibration/Damage Sensing

• Heat Sensing

Smart Structures: Classification

Wada, Fanson, and Crawly

Magnetorheological Fluids

MR Fluids

How do they work?• Externally applied magnetic field

in a direction normal to the fluidflow direction form dipoles in theiron particles

• Magnetic poles start attractingeach others to the direction of thefield, hence forming chains

• The chains then form a skeletonwithin the fluid, which gains thefluid controllable yield stress

Why MR technology?

Mix them and you are done!

Required Materials to synthesize an MR fluid:

• Lithium grease

General purpose oil

Micron-sized iron particles

MR Fluids

Rabinow and Winslow 1950’s

MR Damper Fabrication

Prototype Damper

Seat Shock Absorbers

Shape Memory Alloy

Shape Memory Alloy

• Change mechanical properties with the change of temperature

• Regain original shape when heated!

Shape Memory Alloys

Application

SMA Embedding

Other Applications

• Dental Fillings

• Artificial Joints

• Heat Valves

• Eye-glasses!

Piezoelectric Materials

Piezoelectric Material

• Electric Field Mechanical Strain : Actuator

• Mechanical Stresses Electrical Potential Field : Sensor

Basic Properties

Piezo-Fiber Composites

Active/Macro Fiber Composites

Energy Harvesters

MEMS Power Generation

Backpack Power Generator

Ionic Polymer Metal CompositeIPMC

IPMC

• New Material

• Shape is controlled by electric field

• Designed on the molecule level (NANO technology)

Slow and Fast!

Homework #1

• Prepare a report and a presentation on tow different smart materials of your choice

• At least three different references

• The report and presentation should reflect good understanding of the subject matter

• DO NOT copy sentences or paragraphs from references

• Due 27/9/2010