A fatigue analysis method based on MSR was presented and applied to predict the life of a frame. The finite element modal analysis of frame was performed in the software MSC.Nastran. Secondly, the whole vehicle rigid-flexible coupling model equipped with the frame as a flexible component was built and analyzed in ADAMS/Car Ride to obtain the modal displacement histories through driving on strengthen-road. Then the stress histories of the frame were got by MSR. The life distribution of the frame and the fatigue lives of the most damaged points were obtained. The results are in accordance with those of road tests，and this method is valid to evaluate car-body structure fatigue life at product design stage conveniently.

modal stress recovery(MSR), frame, fatigue life, rigid-flexible coupling

采用基于模态应力恢复的疲劳分析方法来预估某车架的疲劳寿命。首先在MSC.Nastran中对车架进行模态分析，以车架为柔性体建立整车的刚柔耦合动力学模型，在ADAMS/Car Ride中，用试验场强化路面激励进行整车动力学仿真，得到柔性体的模态位移时间历程，然后进行模态应力恢复得到应力历程，通过疲劳分析得到车架疲劳寿命的分布情况和最危险点的寿命值。分析结果与道路试验情况十分相符，证明该分析方法可以在产品设计阶段准确、高效地预估车体结构的疲劳寿命。

模态应力恢复, 车架, 疲劳寿命, 刚柔耦合