Fatigue Life Prediction For Vehicle Drive Shaft Based On Modal Stress Recovery

With the development of the FEM theory, multi-body dynamics theory and fatigue theory, in recent years, fatigue life analysis of auto parts based on the above theory has become one of the hot areas of vehicle research. Vehicle drive shaft as one of the key components of vehicle driveline constantly load asymmetric cyclic stress in the work process, prone to fatigue failure, therefore fatigue strength design is necessary. Currently, the evaluation of the fatigue life of the drive shaft depends mainly on bench test that takes a lot of manpower and resources. The use of virtual prototyping technology for vehicle components fatigue life analysis can greatly shorten the development cycle of the vehicle, saving R & D funding. This paper using the virtual prototyping technology, conduct the structural design of the vehicle drive shaft based on the design parameters of a model, and analyze and study the fatigue life of the key parts cross shaft.Firstly, design the drive shaft of a model based on its design parameters, build the finite element model of the drive shaft, analyze its strength and modal, and make a systematic evaluation.Secondly, analyze the fatigue life of the key parts cross shaft based on modal stress recovery. Obtain the modal neutral file of cross shaft and the results file which contain the modal stress information in MSC.Patran/Nastran. Build the rigid-flexible coupling multi-body dynamics model of the drive shaft in MSC.Adams, simulate the model and obtain the each mode corresponding DAC document which is required for fatigue life analysis. Analyze the fatigue life of the cross shaft by using of the above analysis results in MSC.Fatigue. Ultimately, obtain the distribution of the cross shaft’s fatigue life at specific conditions and its lifetime value of the most dangerous point.Finally, research and study some of the factors affecting the life of the cross shaft. Comparative analysis of the effects of different materials, different port locations, different shapes of cross shaft and different install angles on the cross shaft fatigue life. Discovery that the cross shaft which is using the material of 20CrMnTi can greatly improve its fatigue life; the cross shaft which its oil port is side opening can weaken its fatigue life; the cross shaft which is using the concave shape can slightly reduce its fatigue life to achieve the goal of lightweight design; the drive shaft mounting angle increase will reduce the fatigue life of the cross shaft.The research results can provide a reference for the design of a new car and the improvements of the developed drive shaft product.