Larry Dean Elie

Magnetorheological elastomers: properties and applications

Magnetorhelogical (MR) elastomers are viscoelastic solids whose mechanical properties are controllable by applied magnetic fields. We have developed a family of MR elastomers, comprising micrometer-sized carbonyl iron particles embedded in natural rubber, that can be processed using conventional rubber-mixing techniques. By crosslinking the elastomer in the presence of an applied magnetic field, field-induced interparticle interactions promote the formation of particle chains and columns aligned along the field direction. The resulting composites possess field- dependent of the mechanical properties of MR elastometers enables the construction of controllable elastomeric components, such as suspension bushings, that may prove advantageous in some automotive applications.

Controllable-stiffness components based on magnetorheological elastomers

So-called magnetorheological (MR) elastomers, comprising rubbery polymers loaded with magnetizable particles that are aligned in a magnetic field, possess dynamic stiffness and damping that can subsequently be controlled by applied fields. Tunable automotive bushings and mounts incorporating these materials and an embedded magnetic field source have been constructed. In this article, the response of these components to dynamic mechanical loading is described. They behave essentially as elastomeric springs with stiffness and damping that is increased by tens of percent with an applied electrical current. Their time of response to a change in current is less than ten milliseconds. In addition to a tunable spring or force generator, these components may also serve as deflection sensors.