Analytical and Numerical Investigation of the Strain Rate Field in the Secondary Shear Zone

Abstract

The use of analytical modeling of continuous chip formation in conjunction with orthogonal cutting experiments is proposed in the open literature to identify the material coefficients of constitutive equation within the practical range of stress, strain, strain rate, and temperature encountered in metal cutting. However, most of these approaches do not provide reliable material coefficients since they use average value of the physical quantities in the primary and/or secondary shear zones. The average value of the effective stress, effective strain, effective strain rate and temperature are not very sensitive to the variation of the cutting conditions. The use of distributions of the physical quantities, rather than average values, is believed to provide well-conditioned information for the identification procedure of the constitutive law. An investigation of the primary shear zone has been published elsewhere. The secondary shear zone, characterized by higher temperature compared to the primary shear zone, is being tackled in this paper. An original analytical approach is proposed to investigate the strain rate field in the secondary shear zone for continuous chip formation processes. Based on the distribution of the flow velocity in the primary shear zone and the shape of the secondary shear zone, the field of flow velocity in the secondary shear zone is determined to respect the different boundary conditions. The ability of this approach to predict the velocity and the strain rate fields is assessed by comparing it to the results of numerical simulation of chip formation using DEFORM3D in the case of AISI 1045 steel.