Introduction to Smart Materials

Smart StructuresMohammad Tawfik

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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



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



Shape Memory Alloys



Application



SMA Embedding



Other Applications

• Dental Fillings• Artificial Joints• Heat Valves• Eye-glasses!



Shape Memory Alloys



Shape Memory Alloys



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!



Thank you for your attention!

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Education

Introduction to Smart Materials