Analysis Of Suspension Nonlinear Damping Parameters To Vehicle Vibration And Parameters Optimization

With the development of the automotive industry,the car has become an indispensable part of daily life.Our demands for vehicles were no longer confined to the power,fuel economy,but full vehicle ride comfort,handling stability,safety and other performance indicators.The car as a complex multiple mass,nonlinear vibration system,when the incentive is received,it tends to produce complex vibration response.The strongly nonlinear of a whole vehicle suspension system has a significantly impact on the whole vehicle vibration,thus analysis the influence of the suspension nonlinear parameters to the vehicle vibration and the parameters optimization has a great practical significance.The paper firstly select the widely used ISO2361-1:1997(E)evaluation criteria as the evaluation index of the vehicle vibration.By consulting the research theory and method about the suspension system,the nonlinear simulation of the vehicle is less involved,by analyzing the nonlinear damping of shock absorber velocity characteristic curve of piecewise linear equations in the suspension system,the seven degrees of freedom(7DOF)whole vehicle nonlinear simulation model was established in MATLAB/SIMULINK.Based on an off-road vehicle,obtained by GB/T4970-2009 of method of running test-automotive ride comfort for vehicle random input and pulse enter ride data,then by comparison with the results of the simulation model,the accuracy of nonlinear simulation model was verified.The suspension system strongly nonlinear has great influence on vehicle vibration,thus the paper studied on the nonlinear influence of damping coefficient of variation of parameters on whole vehicle vibration.Results showed that as the rebound stroke or the compression stroke nonlinear damping parameters variation coefficient increase,the root mean square(RMS)of the vehicle vibration acceleration,the RMS of dynamic tyre load(DTL)present the law of first decrease and then increase,and the RMS of the suspension working space(SWS)was decreasing.When the reversed rebound and compression stroke damping coefficient of variation changed,the RMS of acceleration changed very little,the RMS of SWS first decrease then increase,the RMS of DTL first decrease then increase.With the increase of initial opening valve speed of rebound or compression stroke,the RMS of acceleration,SWS and DTL decreased and tended to be stability at last.Finally,by combining the vehicle dynamic simulation model with the MATLAB simulation method,NSGA-II genetic algorithm was used for multi-objective optimization of suspension parameters.By comparison the results before and after optimization,optimization of suspension parameters would change the average RMS of DTL very small,at the same time,the weighted RMS of vibration acceleration of the body gravity center dropped 8%,the average RMS of SWS decreased by 5%.The paper carried out a quantitative study on nonlinear vibration,it is significant for the suspension system performance improvement,and it also has a guidance function for matching optimization of the suspension parameters.