External Characteristic Simulation And Experimental Investigation On Damping Continuous Adjustable Shock Absorber

One of the most important factors that determine the riding comfort and handling stability of the vehicle is the shock absorber.The damping adjustable shock absorber solves the contradiction between comfort and stability,which exists in the common shock absorber.It can also change actively or passively according to different road conditions and vehicle conditions,and have a wide application prospect.At present,the development of domestic shock absorbers generally adopt the “trial-and-error method”,resulting in a series of problems,such as the long development cycle,unstable performance and high cost.So the application of dynamic modeling and simulation technology of shock absorber have an important engineering value for studying on the proper work condition,understanding failure mechanism and improving the design idea.The main contents and conclusions of the thesis are as follows:(1)The working mechanism of the damping adjustable shock absorber were explored based on the theory of fluid throttling and the geometric model.Through the finite element numerical simulation,the accuracy of the analytical equation,which is based on the theory of large deflection,was verified to be accurate.Furthermore,analytical equations for the equal radius superimposed valves and unequal radius superimposed valves were derived.The evolution law of the throttle area of the damping regulator valve with the rotation angle of the valve core was also analyzed.According to the Gaussian function,the analytic equation with high precision was fitted.(2)Both the valves opening velocity and the maximum static friction force of the shock absorber under various conditions were obtained by velocity characteristic test.Besides,both the dynamic models under various conditions and the simulation models under Simulink environment were established,and both the damping characteristic and the speed characteristic of the shock absorber were simulated and analyzed.(3)It was demonstrated that the accuracy of the simulation model meets the requirements of engineering practice by the bench test.The deviation and crossover of the indicator diagram were analyzed theoretically.The results show that both of these phenomena are caused by the hysteresis of internal valve system that is related to complex valve structure and low cleanliness of oil.(4)Based on the established simulation model,the influence law of main parameters on the external characteristics of shock absorbers was investigated,and the conclusions aregiven as follows: 1)the damping characteristics of the shock absorber changed linearly with the change of the fluid dynamic viscosity and the length of annular gap;2)the damping characteristics changed obviously with the change of the annular gap width between0.5mm~1.5mm;3)the compression damping and the rebound damping changes in the opposite direction,causing the change of the compression rebound ratio when the chamber pressure changes.Based on these research results,the key technical references in engineering practice were given: the damping force can be adjusted by adjusting the oil dynamic viscosity and the length of annular gap;the best compression rebound ratio of shock absorber can be obtained by adjusting the chamber pressure.