Unsteady and hysteretic behavior of a magnetorheological fluid damper: Modeling, modification, and experimental verification

Although the quasi-static model is widely employed in various engineering fields to guide the design of magnetorheological (MR) dampers, it is not accurate enough to describe the dynamic behaviors of MR dampers. In this study, an unsteady Bingham plastic (US-BP) model that considers fluid inertia is established. The proposed model can realize flexible switching between flow mode and mixed mode by introducing a mode parameter. To employ the US-BP model for MR dampers under different excitations, a technique combining the Fourier series method and Laplace transform is developed to deduce the velocity profiles of MR fluids. Based on the US-BP model, the damping characteristics of an MR damper under different excitation frequencies, yield stresses, and mode parameters are theoretically investigated. Furthermore, an unsteady hysteretic Bingham plastic (USHY-BP) model that incorporates particle chain deflection theory is developed to characterize the hysteretic behavior and inertia effect of the damping force. Comparisons between the simulation results and the experimental data reveal that the US-BP model can predict the unsteady behaviors of damping forces caused by fluid inertia but fails to capture the hysteresis characteristic. The USHY-BP model achieves good performance and accuracy in characterizing the dynamic properties of MR dampers.