Wrinkling behavior and stress analysis in perforated metal sheets considering cutout geometry and material heterogeneity

Abstract

Cutouts are primarily designed for assembly and weight reduction in sheet metal components; existing research predominantly focuses on structural stiffness and ultimate loading capacity, though several studies address plastic deformation characteristics and wrinkling analysis due to the complex stress states introduced by cutouts. This study employs rectangular strips and Yoshida buckling tests (YBTs) featuring seven cutout configurations with different rotation angles to analyze stress states and their effects on wrinkling. Simulations utilize a proposed initial imperfection implantation method based on material heterogeneity. Results indicate that cutouts increase sheet metal wrinkling sensitivity, causing wrinkling to occur prior to fracture. High stress concentrations around cutout corners dominate wrinkling behavior and increase fracture risk. A novel wrinkling prediction method combining Muskhelishvili's complex variable function with engineering plasticity theory is proposed, yielding an average error of approximately 7.62 % between theoretical and numerical results. However, errors in YBTs exceed those in strips due to greater deviations in effective forming regions and simplified boundary conditions. Although a state of non-uniform compression develops around cutouts regardless of shape, the magnitude and distribution of transverse compressive stress change with cutout shape and rotation angle. Under the combined influence of transverse compressive stress and shear stress near side edges, secondary wrinkling occurs, transforming initially linear edges into S-shaped profiles after post-buckling deformation.