STEADY-STATE AND TRANSIENT MODELS FOR THE ELECTRICAL RESPONSE OF AN ELECTRORHEOLOGICAL CATCH SYSTEM

The outstanding advantage of an electrorheological (ER) fluid as a mec hatronic power transmission medium is the speed of its shear-stress re sponse to the application of an electric field. The costs of this spee d of response are the highly capacitive nature of the interface and a high voltage requirement, which together impose a severe demand on the pulsed power supply. An electrical model of the fluid accurate enough for the elucidation of its control and supply is thus a primary requi rement if the full potential of the flexible motion concept is to be r ealised; the switch on/off time constants of the controller limit the precision of digital motion generation capability, and fluid heating f rom resistive as well as viscous loading requires simulation. Electric al models for the steady-state and transient response of a typical ER fluid to large on and off voltage steps are identified using realistic engineering-scale experimental data from tests on an ER cylindrical/C ouette flow system. The results include a study of the variation of in terelectrode spacing, shear rate, electrode length and the all-importa nt fluid temperature as well as magnitude of the step field excitation .