基于模态分析的白车身有限元模型ACM2焊点单元尺寸研究

Study of the Element Size in ACM2 Spot Weld Model Based on Finite Element Modal Analysis of BIW

ACM2模型采用六面体单元来模拟焊核,然后将六面体的8个节点通过RBE3单元与所焊接的面片单元联结,来模拟焊点,但是关于ACM2模型中六面体单元的尺寸大小尚没有统一的标准。为了研究ACM2单元的最佳焊核尺寸和模拟精度,分别对焊核尺寸为6.0 mm、5.32 mm和4.24 mm时的ACM2单元进行探讨。分析了三种典型的钣金拼接结构,对比分析三种焊核尺寸在基础拼接结构模态分析中的分析精度,将这三种焊核尺寸应用于某A级轿车白车身有限元模型,进行模态分析并且与试验结果进行对比研究。结果表明,焊点尺寸设置为5.32 mm时可以获得最精确的分析结果。

The ACM2 model is a typical finite element spot weld model, which consists of a brick element that is coupled at the 8 corner nodes to the upper and lower shell patch elements over RBE3 elements. However, there is no uniform standard of the brick element size for the ACM2 model. In order to study the accuracy of the model and identify the most appropriate element size, this study discussed three types of element size. The author established the FE model for three typical structures of Body-in-White （BIW） and an A-class vehicle BIW. Then different element sizes used in the ACM2 model were discussed by comparing the correspondirlg modal analysis and testing results. The results show that when using the ACM2 model to represent spot welds in BIW, the element size of 5.32 mm is recommended based on modal analysis.