某轿车白车身模态有限元分析与试验研究

Modal Analysis and Test to Body-in-White of a Certain Vehicle

以某轿车白车身为研究对象,对白车身进行有限元分析,利用白车身模态试验验证白车身有限元结构的正确性。利用有限元位移云图的分布特征,对白车身结构进行优化。实验结果表明:试验车身一阶频率为28.23 Hz,表现为顶棚振动;一阶扭转频率为32.67 Hz,一阶弯曲为45.14 Hz,两个频率错开较远,不会引起耦合共振。通过有限元分析和试验两种方法对比发现,有限元分析和试验频率相差在10%的范围之内。说明建立的有限元模型是正确的。通过有限元分析可以发现,当频率达到25.90 Hz时,顶棚最大变形量为5.427 mm,当频率达到31.45 Hz时,顶盖后部最大变形量为6.512 mm,这会影响到汽车的舒适性、安全性和可靠性,所以要对顶棚和顶盖后部进行优化。

In this paper, setting the body-in-white of a certain vehicle as the study object, finite element analysis on the body-in-white is made, thus the correctness of finite element structure is verified through the modal tests. Furthermore, the finiteelement structure of body-in-white is optimized by using the distribution characteristics of the displacement nephogram. Theresults show that the primary frequency of body-in-white is 28. 23 Hz; while the first torsional frequency is 32. 67 Hz and thebending frequency is 45. 14 Hz, so the two frequencies could not cause coupling resonance. By comparing the difference be-tween experiment and the finite element analysis, it is found that the error is in the range of 10%, so the finite element modelthat was established before is correct. Through the displacement nephogram we can find that the maximum displacement of roofis 5. 427mm at the frequency of 25. 90 Hz, and the maximum displacement of rear roof is 6. 512mm at the frequency of 31. 45Hz, thus it would affect the comfort, safety and reliability of a vehicle. Therefore, it is necessary to optimize the design of theroof and the top cover.