Characterization of a Magnetorheological Damper for Semi-active Suspension Control

Magnetorheological (MR) dampers are commonly utilized in semi-active suspensions due to their ability to adjust the damping coefficient. Notably, they differ from an actuator cylinder in that they feature a solenoid made on the piston, enabling the internal fluid’s magnetization. In passive conditions, without a magnetic field, MR fluid behaves like a standard viscous oil. However, when activated by a magnetic field, the iron particles within the MR fluid align into chains, restricting flow and thus increasing the fluid’s viscosity. This change is reversible; removing the magnetic field restores the fluid to its initial state. To modulate the magnetic field, a controller is required to regulate the electric current in the coil, which in turn adjusts the fluid’s viscosity and the suspension’s reaction to irregularities. This study focuses on the characterization of the RD-8041-1 magnetorheological damper manufactured by the LORD Corporation. The system’s damping values were assessed through characterization tests conducted using an MTS 322 Test Frame universal testing machine, varying both the input current to the device and the imposed velocity. The damping coefficient, as a function of current and speed, can be incorporated into a dynamic model for the semi-active control of the vertical suspension of a seat in an agricultural vehicle. A comparative control performance analysis is proposed, focusing on mitigating oscillations caused by ground irregularities. This is achieved by utilizing the classic SkyHook (SH) method.