aero495 01 introduction
TRANSCRIPT
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 fluid flow direction form dipoles in the iron particles
• Magnetic poles start attracting each others to the direction of the field, hence forming chains
• The chains then form a skeleton within the fluid, which gains the fluid 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 Composite IPMC
IPMC
• New Material
• Shape is controlled by electric field
• Designed on the molecule level (NANO technology)
Slow and Fast!
Homework #1
• Prepare a 2 page report on Piezoelectric materials
• At least three different references
• The report should reflect good understanding of the subject matter: Physics, applications, history
• DO NOT copy sentences or paragraphs from references
• Due 24/9/2012
