Influence of the strain dependent material behaviour under plane strain on the yield locus modelling

Abstract

Modern lightweight materials mostly exhibit a low formability especially in the plane strain state. Having in mind that over 80% of the occurred failures in the press shop in the automotive sector can be related to this strain state, the characterization under plane strain load should be further intensified. The evaluation of the plane strain flow curve is commonly done by notched tensile tests or biaxial tensile tests with optimized strain path. Both tests have some disadvantages in the flow curve evaluation especially at a high degree of deformation. With an elliptic hydraulic bulge test, the material behaviour under near plane strain condition can be evaluated up to fracture. The aim in this investigation is the analysis of the resulting material behaviour under plane strain of commonly used alloys AA5182, DC06 and DP600 with respect to the material anisotropy. Therefore, hydraulic bulge tests with a plane strain load path are performed in rolling direction and transversal direction. The resulting flow curves are used to analyse the material hardening with respect to the anisotropy. The results show differing hardening mechanisms for the investigated materials which will lead to different strategies for the material modelling.