Light Weight Design Research For A Bus Body Structure Based On Topology Optimization

Energy conservation and emissions reduction has become a major research topic ofautomotive industry, and the lightweight of automobile is one of the best ways of energyconservation and emissions reduction of automobile industry. Lightweight of automobilenot only can significantly improve fuel economy, but also has a great influence on vehicledynamic performance. For light bus, the body structure is the main carrier of passengercars, the quality of the bus body, according to the statistics Curb weight of about40%to60%, so the lightweight design of body frame structure of passenger vehicle quality hasvery important significance.The article used a light bus as the object and carries on the optimization designresearch. First analyzed the structure topology optimization design research status at homeand abroad, at the same time in domestic auto specific work of the studies on the structuraltopology optimization design; then expounds the basic theory of finite element method(FEM) and introduction to the basic of finite element software Hyperworks and Nastran;Secondly establish the body frame geometry model, the finite element calculation model,and carries on the static characteristic and dynamic characteristic analysis of body frame isobtained under the combination of bending working condition and bending and twistingworking condition of stiffness, strength, performance and its first6order free modal andvibration model, provide the basis for optimization design of body frame structure.Based on multi-objective topology optimization method and sensitivity analysismethod to optimization design of body frame, firstly introduces the basic theory oftopology optimization, and then set up the mathematical model of multi-objectivetopology optimization and the body frame structure topology iterative calculation, finallybased on results, the topology optimization of body frame structure reconstruction, get inline with the engineering actual production requirements of the body frame structure, andthe new body frame structure performance analysis, results show that under the conditionof quality to reduce, body frame performance has a very good improvement.And on this basis, choosing body frame member thickness as the design variables, theminimum mass of body frame structure as the optimization objective, the body framefirst-order natural frequency, the key parts of stress and torsional stiffness as constraints tosensitivity analysis, obtained the key component of the thickness parameter, optimizationanalysis and according to the sensitivity of results to give body frame structure, get a newbody frame structure.After the new body frame structure obtained by static, dynamic analysis, get the bus body skeleton bending and torsion load under the stress, strain and the first6order free modaland vibration modal, performance and comparative analysis with the original bodyskeleton, in maintaining the body frame structure performance keeps constant andimprove under the condition of body frame structure, reduce the quality of18.45%, andreduced manufacturing costs, improved the utilization rate of material has the goodeconomic efficiency.