Parameter Identification, Modeling, Durability Analysis And Optimization Of Vehicle Suspension System

Aiming to several key problems of suspension, the systematic analysis and researchare carried out. A new analysis method and model is proposed in this thesis, whichcombines the theory calculation and simulation analysis with physical experiment. Theexperiment data is used as the reference, which verifies the validation of new method andthe accuracy of new model. The research contents of this thesis are shown as following:(1)Induce the two freedom degree suspension model considering the nonlinearcharacteristic, providing the theoretical calculation method of offset frequency anddamping ratio. To conquer the deficiency of current calculation method of damping ratio, anew damping ratio calculation method is derivate. In this method, the area method isemployed to calculate the damping ratio, which eliminates the false peak circumstance inthe logarithmic decrement method, so as to improve the estimation accuracy of dampingratio.(2)The sprung mass of automotive with independent suspension may not be calculatedas the sum of each component mass. To avoid the nonlinear characteristic of tyre, asimplified model is proposed, in which the acceleration of wheel center and vehicle bodyobtained by experiment are used to estimate the sprung mass and unsprung mass. Thismethod provides higher accuracy of mass estimation, which has important influence ofsuspension analysis design and research.(3)Build a new nonlinear smooth hysteresis model of rubber bushing, combining theexperiment dates to determine the initial value of parameters, solving the bushingrestoring force. The parameters sensitivity analysis of model is implemented, neglectingthe cross affection of parameters, determining the influence extent to model response ofmainly parameters, which provides reference to the possible model mending. Combiningthe test results of static stiffness and dynamic stiffness, a mended model considering thepreload effect is proposed, which extends the application range of nonlinear smoothhysteresis rubber bushing model. The genetic algorithm is utilized to estimate theparameters obtaining the exact value of parameters, and then compare the simulation results with experiment result verifying the validation and accuracy of model.(4)A new experiment method is used, where the simple and cheap sensors areemployed, testing some more approachable physical quantities such as acceleration,displacement and strain and then back-calculating the six component forces of spindleload. After the six component forces of spindle load are obtained, the forces of joints arecalculated through the multi-body dynamics suspension model, which are compared withthe experiment data to test the validation of reverse solving process and results. Based onthese results, the fatigue lives of chassis components are calculated, and the optimizationchoosing the stiffness of key bushinges of suspension as design variables is implemented,which improves the fatigue lives of chassis components.This thesis is focused on the automotive suspension. Combining some real situationsin suspension research and design, enrich the system of suspension research and design,which makes the process of suspension research and design more reasonable and morenormal, improving the quality and efficiency of suspension research and design. Thecreative method proposed in the thesis has large reality worth and promoting effect onsuspension research and design process.