Modeling On Hydraulic Shock Absorber And Its Application In Vehicle Tuning

With the raise of the maximum speed of the car, the handling and ride comfort are moreimportant than before. Hydraulic shock absorber can affect a number of vehicleperformances, including handling and ride comfort. For example, it can influence the bodyvibration induced by different wavelength pavement road. It can also influence the suddenchanges in body vertical acceleration by impulse road. The tire dynamic load in rough roadcan be controlled by the shock absorber. The shock absorber can also control the roll andpitch angle velocity of the body when cornering, braking and accelerating. At the same time,there are conflicts because different vehicle performances need different shock absorbercharacteristics. In this case, the engineer must have a compromise between different vehicleperformances. This is why the shock absorber engineer is committed to improve the structureof the shock absorber to adapt the conflicting vehicle performance.The shock absorber that this thesis studied has two stages rebound valve, can improve theflexibility of the shock absorber design and tuning. The physical model of this kind shockabsorber is developed. The correspondence between shock absorber parameters andcharacteristics are studied based on the physical model. The modeling process as well as theresearch on the shock absorber characteristics are as follows:1) The physical model of twostages rebound valve shock absorber is developed, there are11tunable parameters in thismodel. The modeling principle, parameter measurement, parameter identification are studiedsuccessively.2) The model is validated using test data.3) Take the rear shock absorber asexample, the correspondence between shock absorber parameters and characteristics arestudied. The results show that the two stages rebound valve shock absorber increase theflexibility of tuning. The second stage rebound valve control the overall characteristics of theshock absorber. The first stages rebound valve control the characteristics below0.1m/s. Thetwo stages rebound valve shock absorber reduced the difficulty of shock absorber tuning.The vehicle performance must be subjective evaluated by experience engineer before theshock absorber in stereotypes. The consturcture parameters can be modified according to theresults of evaluation. In the process of tuning, engineer must understand the correspondencebetween the shock absorber parameters and full vehicle performance. Otherwise, time willbe wasted. Accordingly, the urgent mask is to straighten out the relationship between the valve parameters and the shock absorber characteristics, and study the correspondencebetween the valve parameters and the full vehicle performance clearly. So, the shockabsorber model is linked to the full vehicle model. Then the car performance changesinfluenced by the parameters of shock absorber are studied. The process is as follows:1)Two full vehicle models are developed according to the advantages of the software. TheCARSIM model is suitable for handling, braking and acceleration simulation. The ADAMSmodel is suitable for ride comfort.2) The shock absorber physical model is linked to fullvehicle model, and then the full vehicle model is validated using test data.3) The shockabsorber velocity is counted in all conditions. The parameters which can cause obviouschange in full vehicle are studied. The full vehicle performances are tuned by theseparameters. This method builds a bridge between the damper suppliers and OEMs toimprove the efficiency of the vehicle development. It has practical engineering significance.The nonparametric model of the shock absorber has obvious advantages in shock absorberselection or fatigue analysis of chassis components. The SVR algorithm used for modelingshock absorber is explored. And the nonparametric models of two shock absorbers aredeveloped. The effects of SVR are compared with BPNN and GRNN.In summary, the physical model of two stages rebound valve shock absorber is developed.The correspondences between shock absorber parameters and full vehicle performance arestudied. Innovations in this thesis are as follows:1. The model of the shock absorber which has two class rebound valve is developed, thismodel has11tunable parameters. Step-by-step method is put forward to identify theunknown parameters in the model.2. The influences on shock absorber characteristics caused by the valve parameters areanalysised. The full vehicle performance is tuned by change valve parameters.3. The nonparametric shock absorber model is created using support vector machineregression.