Force lag phenomenon in multi-coil fluid-deficient magnetorheological dampers: experimental investigation and dynamic modeling

Abstract Magnetorheological (MR) dampers, renowned for their tunable mechanical properties and energy dissipation capabilities, have been widely implemented in various vibration control systems. Nonetheless, the preparation and infusion process of MR fluids inherently entails the presence of trapped air, and sealing deficiencies can cause fluid leakage during operation, thereby leading to fluid deficiency within the damper's chamber. Fluid deficiency induces a force lag phenomenon, substantially undermining the damping performance of MR dampers, especially for multi-coil dampers where multiple steps internally restrict the trapped airflow. Existing experimental investigations and mechanical models of MR dampers inadequately consider the force lag phenomenon in multi-coil dampers. Addressing this issue, this study focuses on the experimental investigation and dynamic modeling of the force lag phenomenon in multi-coil MR dampers induced by fluid deficiency. Firstly, performance tests were conducted on a tri-coil MR damper, contrasting force lag phenomenon under varied loading conditions. A dynamic mathematical model was then proposed to characterize this, comprising a series connection of nonlinear spring and hyperbolic tangent elements, in parallel with a damping component, designed to predict multi-coil MR damper behavior under fluid deficiency. Through analyzing experimentally derived force-lag curves, model parameters were determined, leading to the development of a force-lag model for multi-coil fluid-deficient MR dampers. Model calculations were compared with experimental results to verify its efficacy in depicting the altered mechanical properties of multi-coil MR dampers influenced by fluid deficiency. This research furnishes a foundational model for explaining and forecasting the damping performance of multi-coil fluid-deficient MR dampers, facilitating the expanded application of MR damping technology across diverse disciplines.