Simulation of Damping Force for a Magneto-Rheological (MR) Damper Featuring Piston Bypass Holes

The magneto-rheological (MR) damper featuring piston bypass holes is an MR damper with improved mechanical properties relative to conventional MR dampers. It brings much better ride comfort for occupants by minimizing the harshness component from disturbing the smooth ride of vehicles. However, few studies on this MR damper featuring piston bypass holes are found. This work is aimed to study the principle that this MR damper works on by experiment, modelling and simulation. The MR damper featuring piston bypass holes is tested on MTS system. A mathematical model for the MR damper is established. Head loss and local head loss caused by the viscosity of the MR fluid are both adopted in the mathematical model. The Eyring model is adopted to describe the mechanical behavior of MR fluid. The result of simulation is in good agreement with experimental data. When the local head loss is eliminated from the mathematical model, simulation accuracy decreases. These results indicate that the local head loss due to sudden contraction and sudden expansion at entrance and exit of piston bypass holes exists and is significant. The principle that piston bypass holes work on is discussed. This work offers a mathematical model of high accuracy for the design and optimization of MR damper featuring piston bypass holes.