Parameter Identification Applying Full-Field Calibration (FFC) Techniques

The accurate prediction of the material behavior of sheet metals under deformation is crucial for the design and optimization of sheet metal forming processes, which are widely used in many industrial applications. The conventional characterization of orthotropic flow behavior up to failure requires about 60 individual tests, making sample preparation, test execution and evaluation time-consuming and expensive. To overcome this issue, inverse identification strategies are employed using optical measurement systems that provide a transient record of the deformation field on the entire specimen. The comparison of such measured deformation fields with the corresponding simulation results, provides information about the accuracy of the underlying material model and the chosen parameters, namely, modulus of elasticity, formulation and parameters of the yield locus and yield curve [1]. The success of such inverse parameter identification strategies relies on the variety of the strain paths covering the whole possible deformation space occurring in real components during forming and crash. In this paper, we present a study on the optimization of the yield locus of the Barlat 2000 yield criterion by means of Full-Field Calibration and a new specimen geometry. The specimen geometry was designed to enable more representative strain field under complex loading conditions. The experimental data obtained from these tensile tests were used to calibrate the Barlat 2000 yield criterion. The results show that the Full-Field Calibration significantly improves the accuracy of the Barlat 2000 yield criterion in predicting the material behavior of the sheet metal under complex loading conditions.