New Biaxial Specimens and Experiments to Characterize Sheet Metal Anisotropy and Damage

Abstract

The damage and failure behavior of anisotropic ductile metals depends on the material direction and on the stress state. Consequently, these effects have to be taken into account in material modeling and the corresponding numerical simulation, and also have to be experimentally investigated in a controlled and well-reproducible manner. In this context, the present paper focused on new biaxial experiments with the anisotropic aluminum alloy EN AW-2017A. Experiments with the newly developed, biaxially loaded H-specimen were performed with a focus on shear and shear-compression stress states. The formation of strain fields in critical parts of the H-specimen was monitored by digital image correlation, and fracture surfaces were visualized by scanning electron microscopy. Stress states were predicted by corresponding numerical simulations and they facilitated the comprehension of the damage and fracture processes at the micro level. The experiments with shear-compression stress states were realized with a special down-holder to avoid buckling, which enabled a well-controlled study in this generally difficult-to-access range. Furthermore, the anisotropic characterization of ductile sheet metals can be realized by an enhanced experimental program with a wide range of load ratios and loading directions.