Magnetorheological Fluids

Dr. Mohammad Tawfik

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?

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

Modes of Operation

Damper – Valve Mode

Damper – Valve Mode

Clutch – Sheer Node

Structural Damping

Yield Sheer Stress Variations

Rate of Strain with Filed

Homework #4

• Summarize chapter 4 in no more than 5 pages

• Present a derivation for the equations whenever it seems appropriate.