Impact of Material Properties on the Dynamics of MR Dampers

Inhalt:
Magnetorheological (MR) dampers are a unique technology whose output can be controlled by magnetic stimuli. In MR dampers the flow resistance is achieved by varying the apparent viscosity of the smart fluid contrary to variable-orifice semi-active solenoid valves. The outcome is a valveless semi-active device. Clearly, MR devices are engineered to fulfill specific performance criteria. Static criteria usually concern the device’s dynamic range, whereas the set of dynamic criteria involves response time requirements and bandwidth. As the MR fluid’s response time is known to be below 1 ms, only the contributions of the current driver and the solenoid are of importance in practical applications. Design of the current driver and the solenoid should then ensure the required response time and the system bandwidth are met. Therefore, in our study we examine the impact specific material properties have on the output of MR valves. By running a series of time-harmonic finite-element simulations using commercially available ferromagnetic materials we study their influence on the actuator’s bandwidth at the exciting current frequencies up to 100 Hz. The results are presented as plots of averaged (and normalized) flux density vs frequency, respectively.