Determination of damage model parameters using nano- and bulk-scale digital image correlation and the finite element method

In this study, the nano-to bulk-scale fracture behaviors of a dual phase (DP) steel were investigated by combining a micro-digital-image-correlation (micro-DIC) technique and the finite element method (FEM). The emergence of surface cracks and nano-to bulk-scale strain distributions during plastic deformations were investigated using micro-DIC and macro-DIC techniques. FEM simulations were conducted to calculate the stress state of the damaged regions that could not be directly obtained from experiments. By combining nano- and bulk-scale observations, fracture strain and stress triaxiality of both scales were determined into model parameters for predicting the material damage behavior. The accuracy of the present damage model parameters was confirmed by comparing the load–displacement curves obtained from experimental result and proposed method. This new strategy of combining micro-scale deformation behavior and bulk-scale damage analysis facilitates defining damage model parameters through observing a wide range of regions with only one or two specimens, which is opposed to the conventional method that requires bulk-scale observations in multiple loading condition.