Study Of Simulation Techniques For Dynamic Characteristics Of Automobile Shock Absorber

The simulation techniques for dynamic characteristics of automobile shock absorber are important means toward the development of shock absorber technology. They are also the main content of vehicle dynamic characteristics simulation techniques. Facing on the difficulties and problems of traditional shock absorber simulation models, the systemic research on building the distribution parameter model of shock absorber and solving it without the experiment tests was carried out in this thesis.The systemic research on the numerical simulation method of dynamic characteristics of shock absorber was carried out in this thesis. The content includes: nonlinear finite element method, computational fluid dynamics numerical method and fluid-structure interaction numerical method. For the complex fluid-structure interaction system of shock absorber, the fluid-structure interaction simulation method basing on multi-solvers was proposed, that is, the fluid filed is solved by finite volume method, but the solid structure is solved by finite element method, and the data transmission between solvers is passed through coupling surface. This combined simulation method lays the foundation of shock absorber's distribution parameter model building and solving.The CFD simulation analysis and experimental verification for the low speed characteristics of shock absorber's valve were carried out. The structure characteristic, work principle and damping characteristic of shock absorber were analyzed in detail. The relationship between the element density of fluid filed and the calculation accuracy was studied. Then, the fluid field grid model of damper valve with higher accuracy was established, and used for CFD simulation based on laminar model, SST turbulence model and laminar-SST mixed model respectively. The low speed characteristics of shock absorber were obtained. Meanwhile, the internal fluid field rule of shock absorber was revealed. The experiment tests verify that the CFD simulation analysis is satisfactory accurate.The general analytical formula of large deflection for annular throttle-slices in shock absorber was deduced. Chien-perturbation method was used to derive the stiffness curve equation of single throttle-slice in shock absorber. Furthermore, the analytical formula of large deflection for superposition throttle-slices was deduced directly and then generalized. The undetermined coefficients of analytical formula were obtained by finite element method and curve fitting. Numerical results show that the general analytical formula can be used not only for the large deflection calculation (including single throttle-slice and superposition ones), but also for small deflection calculation, and has satisfactory accuracy.The fluid-structure interaction modeling and solving techniques of shock absorber were studied. The calculation accuracy of finite element model of throttle-slice with different mesh styles was studied. The finite element contact model of superposition throttle-slices with higher accuracy was established. The fluid-structure interaction key techniques of shock absorber were analyzed. The fluid-structure interaction dynamic characteristics of shock absorber were simulated and studied. Then, the damping characteristic, the internal fluid field rule and the nonlinear dynamic response characteristic of superposition throttle-slices of shock absorber were analyzed in detail. The performance experiment tests of shock absorber verify that the modeling and solving methods are correct and satisfactory accurate.