Identification of the mechanical material parameters through inverse modelling

Inverse methods offer a powerful tool for the determination of the elasto-plastic material properties. They can deal with complex, heterogeneous stress and strain-fields which have a larger information contents and hence allow the simultaneous identification of several material parameters. Moreover, the obtained material parameters should be more accurate than those obtained with standard methods, since heterogeneous deformation fields are much closer to those occurring under real loading conditions. In this paper the applied inverse method is described in more detail and two applications are presented. The first example concerns the identification of the four in-plane elastic constants of an orthotropic composite material based on a biaxial tensile test performed on a cruciform specimen. The second example describes the identification of the hardening behaviour and the yield locus of a DC06 steel, based on a biaxial test on a perforated cruciform specimen. The plastic material behaviour is described by a Swift type hardening law and a Hill 1948 yield surface.