Static And Dynamic Analysis And Optimization Of An Electric Vehicle’s Body In White

In the modern automotive design process, the Computer Aided Engineering (CAE) is widely used. Based on the finite element theory, building a reliable finite element model of a Body In White (BIW) and doing simulations, with the results compared with the experiment results, it can guide the car body design process, judge the qualities of the car body and improve the weakness of car body. With the energy crisis and environmental problem become increasing serious,《national’s electric vehicle technology developing "12th Five-Year" special program (abstract)》 indicates clearly that the electric vehicle is the developing direction of the national new energy vehicle. In a independent research and develop process of a electric vehicle, this paper does the following work, building a finite element (FE) model of the electric vehicle’s body in white, then doing simulation on the BIW’s static and dynamic properties, figuring out the weakness of these properties, some optimize plans are put forward and carried out, the results show that the static and dynamic properties are improved obviously.This paper briefly describable the electric vehicle’s generating, developing and the current status, with an automotive body’s simulation status as followed. In a electric vehicle’s design process, based on the BIW’s geometry model, using the pre/post process software MSC.Patran2010to create the BIW’s FE model, counting on the modeling time consumption and model accuracy, choosing the Rigid Element2(RBE2) as the spot weld’s simulation element; then using the solver MSC.Nastran2005to solve the FE model’s normal modal, to obtain the first torsion modal and first bending modal, setting the FE model with the same boundaries and loads to the experiment conditions, and calculating the bending stiffness and torsion stiffness of the BIW, making a discussion of the loading methods of the bending stiffness’s load and choosing the way which most close to the real experiment; doing a sensitivity analysis to the BIW’s static and dynamic properties, obtaining the static, dynamic properties and mass sensitivities with respect to the BIW’s different parts’thickness; as the BIW shows local modals in certain modal shapes, by adding stamping ribs to the target parts, and comparing the position of the stamping rib setting, choosing the best program, as the BIW’s bending stiffness is weak, using the sensitivity analysis results as the guidance, by increasing the thickness of sensitive parts to improve the bending stiffness, the results shows that after these modification the bending stiffness is27.62%higher than the original one.The simulate results and optimize plans of the BIW’s static and dynamic characters operated in this paper can guide the electric vehicle body’s improvement, and the analyze process of a electric vehicle which has a unique structure also has a reference significance to the other electric vehicle body’s analysis.