Abstract: Adjustable shock absorber is a key part of vehicle semi-active suspension. According to the damping control demand of electric-controlled semi-active suspension of a certain bus, the structure of a two-levels-damping adjustable shock absorber is designed on the basis of the original passive hydraulic shock absorber of the bus. The deflections of shock absorber’s valve plates are calculated by using conjugate beam method, and a mathematical model for the damping characteristics of the adjustable shock absorber is established. Main structural affection factors to shock absorber’s damping performance such as the piston rod diameter, damping valve orifice and adjustable orifice are analyzed by simulation. Then the damping performance bench test of the adjustable shock absorber specimen is carried out for verification. The test results show that two-stage damping states of shock absorber change obviously, the switching control of damping state is precise, damping force deviations between the test results and the simulation results are less than 8%. It is verified that the established model for adjustable shock absorber has high accuracy and the conjugate beam method for calculating the deflections of shock absorber’s valve plates is available, the research results provide important basis for designing adjustable shock absorber and studying vehicle semi-active suspension.

Key words: Bench test, Conjugate beam method, Damping-adjustable shock absorber, Performance simulation, Valve plate deflection