A unified test for evaluating material parameters for use in the modelling of sheet metal forming

The analytical prediction of forming limits requires the knowledge of material properties such as the strain hardening index (n), strength coefficient (K) and anisotropy (R). These properties can be obtained by conducting uniaxial tensile tests; normally carried out following ASTM (E 8M-93 and E 517-92a) specifications involving specimens of different size and geometry. While the former specification is recommended for determining n and K, the latter, in different forms, is adopted for estimating R. For reasons of economy as well as consistency of testing, it is desirable that the various material parameters are obtained from a single specimen for a given set of process conditions. Hence, the present study pursued a vision-integrated tensile test involving three different types of standard specimens. This comparative study is aimed at exploring the possible evolution of a unified tensile test for determining the material properties that are essential in modelling of sheet metal forming.