Research On Parameter Identification Of ATV Body And Suspension System Assembly

In the research of vehicle dynamics,the physical parameters of the vehicle system play a decisive role in the handling stability,comfort and safety of the vehicle.Therefore,how to accurately and efficiently identify the physical parameters of the vehicle is not only the basis of vehicle dynamics research,but also an important part of it.Using the correct vehicle parameter identification method,the physical parameters of the whole vehicle can be accurately obtained,and accurate modeling data can be provided for the research of various vehicle dynamics problems,which lays a good research foundation.In this paper,the ATV is taken as the research object,the relevant parameters are obtained through the free modal test of the vehicle body and the finite element simulation of the rubber bush,and then the rigid-flexible coupling multi-body dynamic model of the vehicle body and the suspension system is established.Based on this model,the effects of the spring stiffness and installation angle for the shock absorber on the modal frequency of the vehicle body are studied.The specific research contents are as follows:Firstly,the identification method of the inertial parameters of the vehicle body is studied,and the free mode test of vehicle body is carried out by using LMS Test.Lab,and the frequency response function curves between 10 excitation points and 38 response points are obtained.Based on the quality line of frequency response function,the inertia parameters of vehicle body are calculated.Secondly,the material foundation test of rubber is carried out,and the Yeoh constitutive model is selected after fitting the test data onto the hyperelastic constitutive model in the ABAQUS model library.Then,according to the selected material parameters,a finite element model of the rubber bush is established in HyperMesh,and the anisotropic stiffness of rubber bush is obtained through finite element analysis and calculation.Then,in the MotionView software,the multi-rigid body dynamic model of the vehicle body,the front and rear suspension systems is established.Build a body finite element models after HyperMesh software,simulate the seat,fuel tank and other components by adding mass points.The finite element model of the vehicle body is adjusted and compared with the identified modal parameters of the vehicle body to ensure that the error is less than 8%.The flexible body file is generated,and the multi-body dynamics software is imported to establish the rigid-flexible coupling multi-body dynamics model of the vehicle body and suspension system.Finally,the sinusoidal excitation test is carried out on the vehicle body and suspension system,and the multi-body dynamic model is excited under the same conditions.The accuracy of the model is verified by comparing the results of the test and simulation.Then,on the basis of this model,the influence of the spring stiffness and installation angle of the shock absorber on the modal frequency of the vehicle body is studied.The results show that:(1)when the increase in the spring stiffness is50～150n/mm,the increase in the overall modal frequency of the vehicle body is 3% ～50%,and the increase of the elastic modal frequency is less than 3%;(2)when the installation angle of the shock absorber changes in the range of 0 ～ 20°,the reduction of the overall modal frequency of the vehicle body is 0.2% ～ 11%,which has little effect on the elastic modal frequency.The research provides a reference from the rigid-flexible coupling multi-body dynamics modeling and simulation of the whole vehicle.