Theoretical switch model of novel asymmetric magnetorheological damper for shock and vibration application

This study proposed a novel asymmetric conical flow channel magnetorheological damper (CFC-MRD) for all-terrain vehicles (ATVs) to handle complex excitations with coexisting shocks and vibrations. CFC-MRD produces adjustable damping forces by utilizing magnetically controlled properties and achieves asymmetric force output (moderate compression force and strong extension force) with conical flow channels. This design could effectively absorb and dissipate energy. The paper first illustrates the structure and asymmetric principle of CFC-MRD. Then, the mechanism of asymmetric force generation in a non-parallel flat plate is derived, and utilizes the hydrodynamic theory to derive the pressure difference of Bingham fluid between the non-parallel plates. Considering the coexistence of vibration and shock, the study proposes a theoretical switch model that distinguishes between low and high velocity states based on the Reynolds number. Finally, the validity of the model is verified by experiments, and the results show that the CFC-MRD achieves the desired asymmetric force output. The asymmetric force ratio rises with higher excitation speed and drops with increased drive current. At a speed of 1 m s-1 without any applied current, the maximum asymmetric force reaches 1.21. The small peak error, averaging only 2.57%, between experimental and theoretical results affirms the accuracy of the proposed switch model.