The Static Strength Analysis And Optimization Of Car Body Based On Extreme Working Condition Loads

The load situation of moving vehicle is very complex caused by road roughness and a variety of impulsions. As the main load-bearing part, auto-body’s strength influences the safety of vehicle. So the structural strength of parts in body should be taken full account in vehicle designing. Therefore it’s very important to set reasonable load working condition, study stress distributing of Body-in-White (BIW) and optimize the weak stress positions during the auto-body designing.In this paper, four typical extreme working conditions of car body static strength are studied, and the static strength characteristics of a bus’s BIW are analyzed with finite element method. Finally the weak positions of stress are optimized by using structural optimization method. The main content of this paper are listed as follows:Firstly, four typical extreme working conditions and loads are calculated: The previous static strength analysis focused on bending and torsion conditions, while the other conditions were studied relatively few and detailed process of load obtaining in static strength analysis was rarely introduced in other papers. In this paper, based on common working conditions, four typical extreme working conditions of body static strength were studied, i.e. the conditions of Corner and Forward Brake and Twist etc, and obtaining process of required load in car body static strength analysis was detailed illustrated. So the loads of 16 hard-points joined chassis and auto-body were got to calculate static strength of BIW.Secondly, the characteristics analysis of static strength of body structure is conducted: Taking the foundation of finite element method theory, the finite element model for a bus BIW was built up according to the principle of geometric clean-up and meshing compartmentalization. Then taking the loads obtained from four typical extreme working conditions as boundary conditions, static strength analysis of the BIW structure was executed by using inertia relief method. And the weak positions parts like front suspension shock absorber bearing panel were obtained.Finally, cracking analysis and structural optimization of the front suspension shock absorber bearing panel. According to the vehicle road test results and strength analysis data of finite element model, the cracking problems\ of front suspension shock absorber bearing panel in the road test were analyzed, then an improved design was proposed, finally topography optimization was carried out. Through the study in this paper, detailed solutions about static strength analysis and structural optimization of car body are obtained. The method in this paper could be promoted in the structural analysis of chassis parts to achieve higher product reliability, and it has engineering application value and guide significance.