基于虚拟样机技术的轻型载货汽车车架疲劳寿命预测方法

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

为准确预测随机动载作用下汽车车架结构的疲劳寿命,将有限元分析与多体动力学相结合。首先建立了车体结构的多体动力学模型,并将根据中国路况得出的仿真路面谱作为输入,计算了车体11个关键部位的载荷历程。然后在车体有限元模型中计算了相应的应力影响因子。同时根据车架材料的S-N曲线和车架本身的特点拟合出了车架结构的S-N曲线。最后,利用MSC-FATIGUE软件基于准静态应力法的疲劳寿命分析技术,预测了车架结构的疲劳寿命。所预测结构寿命在合理范围内,可以作为车架后续轻量化改进的依据。

For the sake of accurately predict the fatigue lifespan 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 lifespan 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.