Cutting process modeling is still a significant challenge due to the severe plastic deformation of the workpiece and intense friction between the workpiece and tool. Nowadays, a novel experimental approach based on digital image correlation (DIC) technique has been utilized to study the severe deformation of the workpiece. However, the experimentally measured velocity field does not necessarily satisfy the equilibrium equation that is one of the fundamental governing equations in solid mechanics due to the measurement errors; hence, accurate stress fields could hardly be derived. In this paper, we propose a hybrid DIC-FEM approach to optimize the velocity field and generate a stress field that is in an equilibrium state. First, the analysis region for finite element modeling (FEM) is selected according to the captured image, and the DIC results are used to track the deformation history of the material points. Secondly, the deviatoric stresses of the analysis region are calculated by employing the plastic theory. Thirdly, the hydrostatic pressures are acquired through solving over-constrained equations derived through FEM. Finally, the velocity field is optimized to satisfy the equilibrium equation and the boundary conditions (BCs) with the DIC results serving as an initial value of the workpiece velocity field. To validate this approach, the deformations including the velocity and strain yielded by the hybrid method are compared with the DIC results. The stress fields are presented to demonstrate the satisfaction of the equilibrium equation and the BCs. Moreover, cutting forces calculated through the integration of the stress tensors are compared against the FEM simulations and the experimental measurement.
Compression failure characterization of cancellous bone combining experimental testing, digital image correlation and finite element modeling