关键词: 白车身, 静刚度, 弹性体模态, 有限元分析, 静刚度试验

Abstract: The mathematical relationship of simple rectangular frames between flexible modes and static stiffness were generalized to car body in white based on the modal theory in linear systems, and the specific mathematical expressions for stiffness calculation were derived. The modal method which obtained static stiffness by extracting each modal parameters with FEA was described, instead of the previous methods of calculating static stiffness based on the compliance matrix theory and large tests. The results show that, the differences of static stiffness values calculated by two methods respectively are less than 10%, which illustrates that the global static compliance of the car body may be expressed by the sum of all modal compliance contributions, and this calculation method has high precision, so it may provide a reference for target setting of low order modes and stiffness properties. Furthermore, the modal compliance contributions may be an important basis for modal identification. Finally, comparing the finite element calculation results and static stiffness test ones, the errors are less than 8%, especially the torsional stiffness calculation errors are less than 3%, which are calculated by the modal method. So it illustrates that the FEA is reliable.

Key words: body in white, static stiffness, flexible mode, finite element analysis(FEA), static stiffness test