Time-Dependent Method for the Inverse Evaluation of Yield Locus Using Nakazima Experiments

Abstract

The position of the plane strain (PS) point in the stress space depends on the choice of the yield locus. Using non-quadratic yield loci the curvature and therefore the location of PS are determined by the yield locus exponent. On the contrary, the Vegter yield locus offers the opportunity to define exactly the position of PS. Currently, to use this freedom cost-expensive experiments have to be conducted or the position is roughly approximated. In this work, a new method is described to determine the two stress components of the plane strain point for the aluminum alloy AA6016-T4. The time-dependent strain distributions of Nakazima experiments recorded by an optical measurement system are used to conduct a reverse fitting of the PS point. Different strategies of determining the PS point using this new method are compared.