Analytical model of stress field in workpiece machined surface layer in orthogonal cutting

Abstract

Residual stress and strain in workpiece machined surface layer have significant effects on the quality of machined parts, including machining distortion and corrosion fatigue strength. It has been known that the flow stress in workpiece induced by cutting force and cutting temperature during cutting is essential to the generation of residual stress and strain. In this paper, an analytical model of stress field in workpiece machined surface layer in orthogonal cutting is proposed to calculate the stress in workpiece during cutting. In this model, the heating time at a point of interest in workpiece is introduced to improve the original model to investigate its effects on stress distribution. The contours of deviatoric stress components S11, S22, S33 and S12 computed by the original model and the improved model were compared with that of the commercially available finite element model software ABAQUS. The computed results of the improved model show that the stress field in workpiece was in a limited area, which indicates that the stress values on a point of interest would experience increasing and decreasing procedure as the tool moves closer to the point and then travels far away. The results are consistent with that of ABAQUS. Furthermore, the contours of principal shear stress computed by the two models were compared with that of the photoelastic experiment in literature. The computed results of the improved model show the trends that the principal shear stress distribute radially around two radiology centers that locate in the vicinity of the tool tip; the contours of the radially distributed stress around these two centers can be separated by their common tangent; the stress values and gradients closer to the centers are larger, while further are smaller. These trends are consistent with that of photoelastic experiment. However, the computed results of the original model show that the stress field was not in a limited area, indicating that the stress values on a point of interest in workpiece would keep increasing as the tool moves closer to the point and then travels far away, which is not consistent with those of ABAQUS and photoelastic experiment. The improved analytical model of stress field provides a new insight into the stress distribution in workpiece during cutting, and is of great significance to study the residual stress and strain in workpiece machined surface layer.