Damage and fracture in thin metal sheets: New biaxial experiments

In the paper new biaxial specimen geometries for thin ductile sheet metals are proposed. The design focuses on the stress-dependent damage and failure behavior. A plastic anisotropic material model based on Hill’s yield criterion and corresponding associated flow rule is presented and the related material parameters are given. Accompanying numerical simulations reveal the stress state and relate the damage mechanisms to the loading condition. The different proposed specimen geometries indicate various effects on the localization of inelastic strains, the material orientation as well as on the damage and fracture processes. During the biaxial tests strain fields in regions of interest are monitored by digital image correlation and after the experiments pictures of the fracture surfaces are taken by scanning electron microscopy and related to the stress dependent damage and failure precesses. The experimental and numerical results demonstrate the high potential of the newly developed biaxially loaded specimens.