Structural Fatigue Life Analysis Of Coach Frame Based On Coupling With Rigid And Elastic Body

As the bus manufacturing technology is advanced more and more rapidly. The main development trend of future bus manufacturing technology is producing safer, more reliable and lightweight vehicle structure. Nowdays from all over the world the research methods on bus body frame structure under dynamic loading are still relatively small, mainly due to the durability of bus body frame structure field experiment is expensive, and it will take a long time. If using traditional methods quasi-static analysis, by applying constant amplitude loading spectrum the result of static strength analysis will be directly applied to evaluate the fatigue strength of body structure, though it is simple, but it will produce large deviation from the actual service of the bus body frame structure. Based on structural fatigue research in related fields, the article brings forward a method assessing the fatigue life of the bus body frame structure by combing a multi-body dynamic and finite element analysis and compares with the result of static finite element analysis.The main content of this article is to predict the fatigue life of the body. First the bus body finite element model is established, and then verified by experiment. Second establishing a multi-body vehicle dynamics model and the driving road, so that uniform vehicle is put on the stochastic road and incited to access to body fatigue life analysis dynamic load time history. Then the article conducts static analysis of the body frame under bending and torsion condition, so that preliminary to assess the risk static strength location of the body structure. Followed by random excitation of the body frame under transient dynamic response analysis. Finally combing material S-N curve of body frame structure and dynamic load time history derived from multi-body dynamics simulation to conduct the fatigue analysis of the body frame, and compare the weak location of the static strength analysis and fatigue analysis and find two results have greater access.In short the article gives a systemic basic researching idea of fatigue characteristics of the bus body structure based on multi-body dynamics and finite element. Using this integrated method could be more actual to predict early fatigue characteristics of the structure at the early time of the product development, it will provide a good theoretical basis for the fatigue life prediction and effective structural durability testing of the loading structure.