| Taking Landwind X6 sport utility vehicle as the research object, this paper conducts a series of analysis with CAE method to the crack and crack fatigue expanding defects which appears in the chassis and then optimum structural design of the frame is carried out with the results of analysis.First, establish 3D solid model of the chassis with UG software; second, carry out a series of preprocess, such as cleanup geometry, extracting mid-surface, meshing, simulating weld of the suspension to establish a complete and high-quality finite element model of the frame; last, import the finite element model to analyze with ANSYS. The results of the theoretical modal analysis are verified by experiments; therefore the finite element model established is proved to be correct and exact. The results of the subsequent analysis shows that the main cause of the crack appearing in the frame of Landwind X6 off-road vehicle is the unreasonable design, which lies in not only the joint of the suspension arm support and the carling but also the joint of anchoring support of the torsion-bar spring and the carling, the local stress concentration and the insufficient torsional rigidity of the whole frame are caused by this, as a result, the crack and crack fatigue expanding defects appear easily under off-road conditions.The optimum design of structure relevance is carried out by the method of dynamic stress offset. Further analysis shows:this method not only eliminates the local stress concentration of the chassis but also increases the torsional rigidity of the whole chassis and the fatigue strength effectively. In this way, the unitary usability of the chassis is increased.After the frame of the Landwind X6 off-road vehicle is improved according to this method, a lot of road tests and market feedback indicate:the improvement of this frame is reasonable and practical, which reaches its anticipatory aim and this method is applied in the design of new model of Landwind X8. |
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