Wrinkling behavior of laminated steel sheets

Laminated steel sheets sandwiched with a polymer core are increasingly used for automotive applications to improve vehicle’s vibration-damping performance without adding additional weight. It has been observed that the laminated sheets are prone to wrinkling during stamping processes. Due to the significant difference in material properties between the polymer core and the skin steel, FEM prediction of the occurrence, the location, and the shapes of wrinkles in the forming of laminated sheets is still a great challenge. In this paper, the Yoshida buckling test and wedge strip test of laminated steel and its steel skins were conducted. The information of local strains, buckling heights and global wrinkling patterns were obtained in order to study the initiation condition of wrinkling and the post-buckling behavior of the sheets, and to provide verification data for numerical predictions. Rectangular panel forming tests were also conducted. The results showed that the 1.0 mm laminated sheet employed has a wrinkling tendency similar to that of its 0.5 mm skin panel and has a strain distribution similar to that of its 1.0 mm solid counterpart.