Study On Nonlinear Parametric Modeling Of Telescopic Shock Absorber And Software Development

As an energy dissipation device,well-designed shock absorber can effectively reduce harmful vibration and thus being used in various industrial products.An accurate model of shock absorber can be used to guide the design process,reducing enterprise's cost and improving efficiency.This thesis studies the primary vertical shock absorber applied in high-speed railways with theories of elasticity mechanics and fluid mechanics.A nonlinear parametric model of shock absorber is firstly established based on the finite element analysis with purpose of throttle-slice deflection calculation.Then a software which can simulate the damping characteristics is developed.To solve the problem of throttle-slice deflection calculation,several representative methods are compared.The results indicate that the finite element method is the only one that is effective in regional loading case,and a conclusion is thus drawn that the influence of large deflection can be ignored when the throttle-slice deflection is smaller than its thickness.In that basis,the finite element program used for throttle-slice deflection calculation is coded.This program can also be embedded in the damping characteristics simulation model of shock absorber directly.In addition,the equivalent thickness formula of disc valve in special loading case is generalized to more complicated regional loading case.Some principles and basic assumptions are given in the thesis,on that basis,formulas of the relation among pressure difference,flow of the piston valve system and the bottom valve system are deduced.Flow continuity equations are also established considering the flow leakage.The oil viscosity-temperature characteristics is finally analyzed,thus completing the nonlinear parametric modeling of shock absorber.The overall simulation project based on the pressure differential increment iteration method is proposed.The core of this method lies in calculating flow with given pressure difference and using the ratio of pressure difference between disc valve and pressure difference of the piston in the last calculation step,and the purpose is to update the pressure difference of the disc valve in this calculation step.A bench test of shock absorber is carried out,and compared with the simulation results the accuracy of the nonlinear parametric model is verified.At the same time,parameter sensitivity analysis of the shock absorber's damping characteristics is given with parametric model in terms of constant throttling orifice,the pre-deflection of throttle-slice,equivalent thickness of disc valve,flow leakage and temperature.A damping simulation software is finally developed basded on the nonlinear parametric model of shock absorber by hybrid programming method of Matlab and Visual C++.The validity and reliability of the software is also proved by computing instances.