Finite Elements Analysis And Optimization Of Heavy-duty Truck's Frame

Frame is an important assembly bearing loads of an automobile .All kinds of loads will pass to it .So the performance of frame structure affects whether the automobile design is successful or not .With the rapid development of automobile industry the performance request becomes stricter and stricter ,which makes conventional calculation methods of design can't meet the needs of modern automobile design .The appearance of computers and the development of finite element method bring on a new revolution about the calculation and analysis of automobile frame structure .Using finite element method to analyze automobile frame structure and taking frame structure optimization into account make sense in improving automobile performance ,reducing the cost of design and manufacture of cars and increasing capability of market competition.With reasonable and suitable simplifications, a fine FEM model of the frame was established by using Hypermesh .The modal analyses of the frame were processed in Nastran .static analysis, include bending ,torsion were implemented on to the frame for simulation .The results of stress and deform presented the evidence of the weakness of the frame . Static and dynamic experiments of the frame were expatiated, the results of the experiments have testified the analysis done above, and offered practical foundation. Natural frequencies of the frame were obtained through modal analysis and the results were analyzed.Based on the former modal results, To ascertain the change of the component thickness of the frame to the influence of the first class frequencies, the sensitivity analysis was performed. Base on the sensitivity analysis we can get more rational design parameters in the following optimization analysis. So in the paper the concept and significance of sensitivity analysis is the main motive.In the followed optimization analysis, the parts which have more influence to the low-order modal were selected, and the thickness of these parts were set as design parameters. In the optimization design, different object functions can be designed according to different purpose. Refer to the similar researches, in this paper two object functions were designed, which were the weight of the frame and the frequency values of the low-order modal.The systemic flow was established for the dynamic analysis of the frame, which is"modal analysis-sensitivity analysis-optimization analysis". The flow can apply to any other similar research. The item accumulated some experience for some correlative research. The result provided a valuable consult for the further optimization of the frame.