Study Of Vehicle Body Framework Optimization Based On Regional Analysis And Visualization Model

Body is an important part of a vehicle and the body development occupies a leading position in the vehicle development process. The performance of the body has a great influence to vehicle performance. Vehicle body framework consists of beams and joints, which is the foundation of the vehicle and undertakes the major loads. For those reasons, it is particularly important to optimize the body framework for improving the performance of vehicle body.The present stiffness calculation and evaluation method only reflect the body stiffness and the torsion curves of the cross beam or threshold, it can hardly be used to evaluate the stiffness matching characteristics and the contribution of local region in body comprehensively. Aiming at this problem, a stiffness evaluation method based on regional contribution was established, with the strain energy and strain energy density as analysis object. The regional sensitivity was used to analyze the influence of regions to the vehicle performance. They were combined to comprehensively evaluate stiffness matching characteristics of vehicle body. The body framework was divided into joints and beams. The stiffness contribution, material contribution and regional sensitivity of each region under stiffness condition and free mode condition were calculated.In order to analyze the results of regional contribution and regional sensitivity intuitively and vividly, a tube visualization model was constructed to make the numerical value visualized. The construction method was detailed illustrated and the visualization model construction flow based on regional analysis results was summarized that laid a foundation for the visualization displaying system. The engineers would not need to do the multifarious data analysis job, but in an intuitive way by the visualization of value.The visualization displaying system based on UG platform was established by secondary development. The calculation results could be extracted from data file and the regional contribution and sensitivity vi sualization models were automatic generated respectively. The stiffness matching characteristics of vehicle body were summarized through the visualization model and structure modification suggestions were put forward. Because the visualization displaying s ystem was integrated in UG platform, body engineers could view the FEM results conveniently, analy ze the stiffness matching characteristics and find out the problems intuitively. It could give guidance for body structure matching and had engineering applic ation value.According to the previous analysis, the body joints key regions were selected as optimization objects, the relationships of the different thicknesses of parts in the same region were set up. The thicknesses of regions were chosen as design var iable, the stiffness and mode frequencies were chosen as constraints, the body mass minimization was chosen as target. The approximate model established by DOE was optimized using genetic algorithm. The structure was modified according to the optimization results and engineering practice. Finally, the stiffness and mode performance of vehicle body were improved with the mass increasing in a small range. The stiffness contributions visualization and material contributions of the regions after optimized were compared with the former ones. It indicated that the body structure stiffness matching was more reasonable after optimization.