Experimental validation of a magnetorheological fluid activation flow CFD analysis

Abstract Magnetorheological (MR) fluid-based devices operating at high speeds exhibit a phenomenon termed “high-speed yield force falloff,” characterized by a decrease in the force difference between field-on and field-off states with increasing velocity. This behavior, observed in various applications, contradicts predictions from existing simplified force models that assume constant yield force and employ oversimplified one-dimensional fluid dynamics. Consequently, these models become inaccurate at high speeds due to the increased nonlinearity of the fluid dynamics. This study validates a previously developed two-dimensional computational fluid dynamics (CFD) model, the “activation flow model,” against experimental data obtained from a high-speed MR impact damper. The model accurately predicts the observed yield force falloff, confirming that the primary cause is momentum flux changes within the fluid’s plug region. These findings demonstrate the activation flow model’s potential for accurately predicting high-speed MR device performance, enabling a more robust design of MR impact dampers.