Fatigue Strength Analysis and Comparison Front Sub-Frame by Two Kinds Of Welding Model

Front sub-frame is the key bearing component of chassis, which can improve the suspension connection stiffness and optimize the ride comfort of the vehicle, and has an important impact on the vehicle performance. With the development of automobile industry and the improvement of relevant laws and regulations, countries have put forward higher requirements for the safety performance of automobiles, and durability test has become one of the most critical links of research and development. Firstly, element model of sub-frame finite is established, and then simulated respectively with rbe2 element and beam element welding model; by modal and life-cycle analysis based on the MSC.Nastran and MSC.Fatigue software, the 10 stages vibration frequency, the distribution of fatigue life and the dangerous sites of the sub-frame were respectively obtained. By comparing with the bench fatigue test data, rbe2 welding mode is more close to testing results, and has a higher accuracy, the data coincidence can be up to 95%. This work can provide the basis for the optimization of the bench test and sub-frame structure design.