Impact analysis of geometric characteristics and boundary conditions on the stiffness of sheet metal parts

This article discusses the traditional stiffness characterization of sheet metal, examined the impact sensitivity of general cover panel geometry to the sheet metal stiffness, and determines the main factors affecting it. The sheet metal stiffness was characterized using both material and geometry properties. Extensive study was conducted on the effects of boundary constraints to the sheet metal stiffness, along with analysis of same range center stiffness variations due to different size boundaries and positions. These research results showed that for automotive body panels, internal bulge or dent geometric feature is the most sensitive factor affecting its stiffness, as long as its height is within the range of (10 ~ 25) mm. Under unilateral constraint conditions, the sheet metal stiffness exhibits a logarithmic relationship with respect to material and geometry properties; under bilateral constraint conditions it’s linear. The stiffness in the same size range is basically the same even when the boundary dimensions are different. Within the same sheet metal, the stiffness in the same size range is the minimum around the edges, and basically is the same across the internal regions. This research work provided significant insights and guidance to the optimization of the main body section design, as well as the improvement on the assembly precision of body panels.