Structure Performance Analysis And Optimization Of Frame Structure On Electric Bus

Regarding bus frame as the research object,the static and dynamic mechanical performance of the original frame are studied in this paper,and the existing problems are optimized to improve the mechanical properties of the frame.In order to avoid stress singularity and reduce the amount of computation,the original frame is simplified and passivated to ensure the stability of the stress solution.Then,by establishing several L-type angle steel and comparing the stress and deformation results under different grid sizes,the optimal grid size of the frame is determined,and the stress and deformation correction coefficient under the optimal grid size will also be determined.In the static analysis,gravity and horizontal inertial forces are simulated by adding mass element on the surface of shell element,the FEA result illuminates that the stress and deformation of the original frame could meet the design requirements,but there are unreasonable the local structures in original frame,and the primary and second natural frequency of the original frame are easy to resonate with the excitation caused by wheel unbalance and the third natural frequency is easy to resonate with the excitation caused by transmission shaft.Therefore,the static and dynamic performance of the original frame needs to be further improved.With consideration of the above problem,the purpose of improving stress distribution,avoiding resonance and reducing weight will be achieved by optimizing design.Firstly,the Path of Force Transfer under the combined conditions is determined by topology optimization.Secondly,Based on the Path of Force Transfer of topology optimization,the frame shape is designed preliminarily.Then,through the size optimization of the new frame,the optimal thickness of all section bars is determined.Finally,the static verification calculation shows that the optimized frame could effectively improve the stress distribution and make stress more reasonable;The dynamic verification calculation shows that the primary and second natural frequency of the original frame could effectively avoid the excitation caused by wheel unbalance and the third natural frequency are effectively greater than the excitation caused by transmission shaft.In addition,the total weight of the optimized frame is reduced by 72 kg,achieving the goal of lightweight design.