Response time of magnetorheological fluids and magnetorheological valves under various flow conditions

In this study, the response times of magnetorheological fluids and magnetorheological fluid valves are studied under various flow configurations. Two types of valving geometries, annular flow and radial flow, are considered in the magnetorheological fluid valve designs. The transient pressure responses of magnetorheological fluid valves are evaluated using a diaphragm pump with a constant volume flow rate. The performance of each magnetorheological valve is characterized using a voltage step input as well as a current step input while recording the activation electric voltage/current, magnetic flux density, and pressure drop as a function of time. The variation of the response time of the magnetorheological valves under constant volume flow rate is experimentally investigated. The Maxwell model with a time constant is employed to describe the field-induced pressure behavior of magnetorheological fluid under a steady flow. The results demonstrate that the pressure response times of the magnetorheological fluid and the magnetorheological valves depend on the designs of the electric parameters and the valve geometry. Magnetorheological valves with annular flow geometry have a slower falling response time compared to their rising response time. Magnetorheological valves with radial flow geometry demonstrate faster pressure response times both in rising and in falling states.