Full-field inverse identification of elasto-plastic model parameters for ductile cast iron

A key challenge in micromechanical simulation of ductile cast iron is the identification of the constitutive properties of the microstructural constituents. In recent scientific literature, ductile cast iron is predominantly modeled isotropically. Applied methods for the determination of model parameters for ductile cast iron include characterization by nanoindentation as well as inverse modeling approaches. In the present work, effective elastic and plastic model parameters for ferrite were determined by full-field inverse calibration. For that purpose, a stochastic speckle pattern was introduced in tensile specimens by focused ion beam (FIB). In situ experiments were carried out in a scanning electron microscope and the strain in ferrite was measured by digital image correlation (DIC). A micromechanical model was built from the microstructure of the in situ experiment. Measured and simulated strains were used in an optimization procedure to identify reliable plasticity parameters of ferrite in ductile cast iron. The results reveal the limitations of modeling the former isotropically.