Elasto-plastic material parameter identification by inverse methods

Inverse methods offer a powerful tool for the determination of elasto-plastic material properties. Contrary to standard tests, these methods 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 realistic, since these heterogeneous deformation fields are much closer to those occurring in real (metal) forming operations. In this paper an inverse method is presented for the determination of the unknown material parameters of a DC06 steel. The material behaviour is described by a Swift type hardening law and Hill's 1948 yield surface. The parameter update algorithm is a gradient based Newton-type optimization algorithm. The importance of a suitable material test and the update algorithm itself are discussed in more detail.