Heterogeneous testing model calibration as input to virtual forming of dual phase steels

The mechanical characterization of materials, such as advanced high strength steels, typically requires a series of quasi-homogeneous mechanical tests, necessitating the use of multiple specimens to fully reproduce the large range of strain states characteristics of forming processes. Recent studies have shown that heterogeneous testing can provide enough data in a single test to cover several strain states, providing an alternative way. The design and choice of the heterogeneous test is still a matter of investigation and validation of the model calibration in virtual forming is needed. The aim of this study is to calibrate a mechanical model for a dual phase steel from heterogeneous test data. The material was provided as sheets of 0.8 mm thickness. Experiments were carried out using a specimen designed by a topology-based optimization, exhibiting a complex shape and a variety of strain states. A finite element model updating method is used to calibrate an anisotropic hardening plasticity model. Then, the study explores the practical relevance of these parameters in a forming application, in the case of the Material-Under-Control (MUC)-Test and a cup drawing process. The strain and stress states of the heterogeneous and the forming processes are analysed. The focus of the study is to compare numerical predictions of the forming processes obtained either using material parameters identified from the heterogeneous test or with quasi-homogeneous tests.