Research On Heavy Vehicle Balance Shaft Fatigue Life Of Based On The Multibody System Dynamics

Heavy duty truck balance shaft is the key technology of automobile chassis, and its main function is to transfer the vertical reaction force, longitudinal force and lateral force from the road surface, and impact load of the non ideal road surface transmitted to the frame. So the working performance of the balance shaft determines the motion characteristics of each part of the vehicle and the ride comfort and safety of the vehicle. It is necessary to balance the axis as the research object, and study on the vehicle rigid flexible coupling multibody dynamics, the vehicle road roughness input excitation, and the fatigue life prediction, then build the research methods of fatigue life of automobile components with reliable and effective form.In this paper, according to the working characteristics of the three axis heavy vehicle balance suspension, the vehicle suspension system dynamics model with nine degrees of freedom is established, and the vehicle system dynamic equations are derived. The system simulation of the whole vehicle state equation is built, and combination improved RLS identification algorithm, then the vehicle parameters are re-identified.Secondly, through the research of rigid flexible coupling force element, the rigid-flexible coupling multi-body dynamics equation is obtained under the generalized coordinates. And Discrete numerical solution of the dynamic equations by the Newton-Raphson iteration method. On the other hand, the front axle and rear axle model of the truck is built, and the model are validated by the frequency response characteristic of the suspension system. The state equation of the heavy truck six wheel road roughness input excitation is obtained by using transfer function method, then build the whole vehicle road roughness mathematical model in Matlab/Simulink, and the correlation degree of the road surface roughness is verified by the mutual relations.Finally, after the completion of the vehicle rigid-flexible coupling multi-body modeling research and simulation of road roughness, the random load spectrum of the balanced suspension parts is obtained by using the method of the Modal Stress Recovery. Then the random load is analyzed by the counting method, chose the nominal stress method, the fatigue life of the balanced shaft parts is obtained in the end, and the prediction of fatigue life can meet the requirements of practical application...