Structure Characteristic Analysis And Fatigue Life Prediction Of The Car’s Sub-frame

With the development of science and technology and society, people’s living standards and quality of life have become increasingly demanding, The car as the main means of transportation for people’s daily life, its performance has become more and more important。The vehicle’s comfort and manipulation stability is its performance primarily reflected。The sub-frame is made into produce In order to improve the performance. That car’s sub-frame is supporting the engine and gearbox. The engine connected with the vehicle body through the sub-frame can Effective attenuation and isolation of engine vibration Compared with the traditional car which has no sub-frame.This article take the Shanghai Volkswagen sub-frame as research object Do the structure dynamics analysis and prediction Fatigue life of sub-frame. First scanned the sub-frame using FARO three-dimensional laser scanner, in order to Get the3D coordinate of point cloud, then use reverse remodeling technique to get3D model of the car’s sub-frame, establish finite element model in hypermesh and do free modal analysis in ansys. through Those we can gain the ten order modal parameters and vibration type of the sub-frame, We can know the modal values higher than the modal values of ground resonance and avoid resonance when reference for automotive industry standards. Do the constraint modal analysis on the sub-frame after that, we build the rigid-flexible coupling front suspension model. and calculation the sub frame’s load and dynamic simulation of the limit braking condition, Analysis the dynamic characteristics on the sub-frame’s main positions. The dynamics vehicle model which contained the flexible sub-frame was established in ADAMS/CAR, and do dynamics simulation under the random road excitation, that get the load time course of the sub frame’s different junction. Combined with material S-N curve, obtain the sub-frame overall life distribution nephogram, The results show that the most of the sub-frame basic to satisfy the use requirements and Pointed out that the lower position and the reasons of fatigue life on the sub-frame. And also put forward the corresponding improvement suggestion.The whole thesis has provided a constructive suggestion on Structure Characteristic Analysis and Fatigue Life Prediction of the Car’s Sub-frame which has very real and very important significance.