1. Magnetorheological Fluids
Dr. Mohammad Tawfik

2. 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

3. Why MR technology?
Required Materials to
synthesize an MR fluid:
• Lithium grease
 General purpose oil
 Micron-sized iron particles

4. MR Fluids

5. Rabinow and Winslow 1950’s

6. MR Damper Fabrication
Prototype Damper

7. Seat Shock Absorbers

8. Modes of Operation

9. Damper – Valve Mode

10. Damper – Valve Mode

11. Clutch – Sheer Node

12. Structural Damping

14. Yield Sheer Stress Variations

15. Rate of Strain with Filed

16. Homework #4
• Summarize chapter 4 in no more than 5 pages
• Present a derivation for the equations
whenever it seems appropriate.