Prediction method of fatigue life-span of light-duty truck frame based on virtual prototype technology

For the sake of accurately predict the fatigue life-span of automobile frame structure under the action of random dynamic loads;let the finite element analysis and multi-body dynamics be combined together.Firstly the multi-body dynamics model of vehicle body structure was established,and let the simulative road surface spectrum obtained according to the Chinese road condition to be taken as the input so as to compute the loading courses of 11 key positions of vehicle body.After that the corresponding stress influencing factors were calculated in the finite element model of vehicle body.At the same time the S-N curve of vehicle frame structure was fitted out according to the S-N curve of vehicle frame material and the characteristics of vehicle frame itself.Finally,utilizing MSC-FATIGUE software and based on the fatigue life-span analytical technology of the quasi-static stress method,the fatigue life-span of vehicle frame structure was predicted.The being predicted structural life-span was within the rational range and can be acted as a basis for the subsequent light weighting improvement of vehicle frame.