ELECTRORHEOLOGICAL DAMPERS .1. ANALYSIS AND DESIGN

Electrorheological (ER) materials are suspensions of specialized, micr on-sized particles in nonconducting oils. When electric fields are app lied to ER materials, they exhibit dramatic changes (within milli-seco nds) in material properties. Pre-yield, yielding, and post-yield mecha nisms are all influenced by the electric field. Namely, an applied ele ctric field dramatically increases the stiffness and energy dissipatio n properties of these materials. A previously known cubic equation whi ch describes the flow of fluids with a yield stress through a rectangu lar duct can be applied to annular flow, provided that certain conditi ons on the material properties are satisfied. An analytic solution and a uniform approximation to the solution, for the rectangular duct Poi seuille flow case is presented. A numerical method is required to solv e the flow in annular geometries. The approximation for rectangular du cts is extended to deal with the annular duct case.