Modelling and Simulation of a Magnetorheological Fluid Damper with Multi-Accumulator during Mode Shifting

In a monotube magnetorheological fluid damper (MRFD), there usually exists a compensation chamber with designated initial gas pressure. This enclosed compensation chamber works as an air spring to some degree to provide force to the working piston. In this work, in order to extend the external damping force range and improve the controlling efficiency, a structure of MRFD with three additional accumulators is proposed. These additional accumulators are connected to the atmosphere through an air pump and the compensation chamber with a barometric valve. The external damping force range thus can be rapidly adjusted through mode shifting with this configuration. A mathematical model of this damper with coupled effects between the air and the magnetorheological fluid (MRF) is developed. Comparing the bench tests results with some simulation outcomes, the simulation model of this MRFD is validated. Influences of moving speed of the working piston, air pressure and initial volume of the accumulators on the external performances are simulated. Simulation results tell that the coupled effects between the additional accumulators and the MRF can provide rapid mode shifting and extensive external damping forces. The air pressure in the compensation chamber and the accumulators can translate the external force-displacement curve linearly and deform it slightly. Mode shifting of the initial volume of the accumulators can make significant distortion of the external performance curves if the initial volume is small enough, while the influence is negligible if their initial volume is large enough.