The Research On The Methods Of Fatigue Life Prediction For Vehicle Body Based On Real Road Conditions

With the development of the automobile industry, the fatigue durability isbecoming a major performance, and has a direct impact on the market competitiveness.The performance evaluation usually depends on real vehicle test or computersimulation technology. Real vehicle test period is long and the costs are enormous, andit cannot predict fatigue life in the early stage of automobile development. Computersimulation technology can avoid the disadvantages of real test. This paper conductedthe systematic study of computer simulation technology for body structural fatigueprediction.For the problem of low accuracy of computer simulation technology, the methodof fatigue life prediction for vehicle body based on real road conditions was proposed,and also applied in the fatigue durability project of certain commercial vehicle. Firstly,the paper established the rigid-flexible coupling dynamic model of the vehicle, andvalidated the finite element model of body and the multi-body dynamics model ofsuspension system. Then the long virtual road which consisted of a variety of typicalpavements was built and used as the excitation of virtual test, and the speed based onthe provisions of real test was applied to controlling the simulation speed of virtual test.So the virtual test could be a true reflection of the road conditions of the provingground, and improve the accuracy of the dynamic loads that the virtual test obtained.Finally, the linear superposition method was used to predict the fatigue life.In addition, it was proven that the virtual test could truly reproduce vehicle loadat the real proving ground, by comparing between the measured and simulated valuesof accelerations of wheel hub. And through fatigue analysis and structure optimizationof the front wheel cover connecting plate which had cracked after the test of Hainanproving ground, the paper’s method was proved that could accurately and effectivelypredict the fatigue life of vehicle body structure, and be instructive and meaningful tothe fatigue performance improvement. Therefore, the method had an important role inreducing the number of real vehicle tests and the research and development period andcosts, and had very important engineering application value.