中文摘要：

CFAST类型焊点单元在建模时不要求网格节点对齐，是一种效率较高的焊点模型。但是CFAST单元在车身模态分析方面的应用研究较少。详细讨论了CFAST单元的使用方法，并利用CFAST模拟焊点建立某A级轿车白车身模型进行模态分析。有限元模态分析与模态试验结果的对比表明，CFAST单元模拟焊点，在模态分析中具有较高的计算精度。

英文摘要：

The CFAST element, which does not require alignment of the mesh nodes, is an effective spot weld model, However, little attention has been paid to the study of the CFAST element in the field of automotive simulation. This article first described the basic theory and applications of the CFAST element.Then, the body in white （BIW） finite element （FE） model of an A-class vehicle was built and its FE representations were explained. The spot welds of＂ the vehicle were modeled using CFAST elements and then the modal analysis was carried out for the FE model. In order to confirm the numerical results, the modal test for a real BIW of the vehicle was conducted. The comparison between numerical simulation and experimental results shows that the CFAST element can be used to represent spot welds with good accuracy in modal analysis.