Abstract: The structure and working principle of a vehicle single-rod and twin-tube magnetorheological fluids(MRF) damper based on pressure driven flow mode is introduced. The MRF damper is designed with the existing manufacturing standards of ordinary hydraulic damper, which has a strong succession technology on the existing vehicle suspension damper. The mathematical model of damping force is established using non-Newtonian fluid model and Bingham plastic model, and magnetic circuit design method of the MRF damper is proposed. Based on the non-axisymmetric magnetic circuit of piston, a magnetic circuit three-dimensional finite element simulation model is established with the ANSYS software，and the magnetic circuit parameters are determined according to the technical requirements of a front Beijing Hyundai vehicle damper and the MRF rheological properties. The twin-tube MRF damper is designed and produced, and the experiment is done to test the damper characteristics. The simulation results are compared with testing results. The results show that they agree well, and the proposed design of twin-tube MRF damper is proved to be right, which is a guide for design and use.

Key words: Damping force, Magnetorheological fluids damper, Pressure driven flow mode, Twin tube