Sensitivity of magnetorheological damper behavior to perturbations in temperature

In this study, the temperature dependent dynamic behavior of a magnetorheological (MR) damper is characterized. Substantial effort has been devoted to developing an understanding of the dynamic behavior of MR dampers with virtually no emphasis on temperature effects. However, MR dampers can experience large variations in temperature during operation as a result of damper self-heating, which may cause significant perturbations to its damping and yield force. Temperature variations also induce stiffness changes in the pneumatic accumulator due to gas law effects. To model temperature dependent effects, an MR damper, which was designed and fabricated for a ground vehicle seat suspension application, was tested over temperatures ranging from 0 °C to 100 °C at a constant frequency of 4 Hz and a constant amplitude of 7.62 mm on an MTS-810 material testing system equipped with a temperature-controlled environmental chamber. To model the MR damper behavior, a parametric algebraic model was used due to its physically motivated, low computational cost and high accuracy. Temperature dependent model parameters are identified from the experimental data by using a curve fitting method. Perturbations in model parameters arising over the tested temperature range indicate that yield force and post-yield viscosity are strongly dependent on temperature. As operating temperature increased from 0°C to 100°C, the controllable yield force decreased by up to 20%, the post-yield damping decreased by over 60%, and the stiffness at high piston velocity also increased significantly.