International Journal of Machine Tools & Manufacture 43 (2003) 573–587 Residual stresses and strains in orthogonal metal cutting C. Shet, X. Deng * Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA Received 7 August 2002; received in revised form 29 October 2002; accepted 3 January 2003 Abstract The finite element method is used to simulate and analyze the orthogonal metal cutting process under plane strain conditions, with focus on the residual stress and strain fields in the finished workpiece. Various modeling options have been employed. The frictional interaction along the tool-chip interface is modeled with a modified Coulomb friction law. Chip separation is modeled by the nodal release technique based on a critical stress criterion. Temperature-dependent material properties and a range of tool rake angle and friction coefficient values are considered. It is found that while thermal cooling increases the residual stress level, the effects of the rake angle and the friction coefficient are nonlinear and depend on the range of these parameters. The predicted residual stress results compare well with experimental observations available in the literature.  2003 Elsevier Science Ltd. All rights reserved. Keywords: Finite element simulation; Orthogonal metal cutting; Residual stress 1. Introduction Machining operations such as orthogonal metal cut- ting are complex nonlinear and coupled thermomechan- ical processes. The complexities are due to large strain and high strain-rate in the primary shear zone and due to the contact and friction between the chip and tool along the secondary shear zone. In addition to the above, complexities are also caused by local heat generation through the conversion of plastic work in the chip during chip formation and the frictional work between the tool and chip. An undesired byproduct of the metal cutting process is the creation of residual stresses and strains in the freshly cut workpiece, which is known to affect the integrity of the newly finished surface, including short- ened creep and fatigue lives of the machined component under service loads. Hence a careful assessment of the residual stress and strain fields in the workpiece is neces- sary for optimizing the cutting process and for safe- guarding against the premature failure of machined parts under creep and fatigue loading conditions. A significant amount of metal-cutting research work * Corresponding author. Tel.: +1-803-777-7144; fax: +1-803-777- 0106. E-mail address: deng@engr.sc.edu (X. Deng). 0890-6955/03/$ - see front matter  2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0890-6955(03)00018-X has been carried out in the past 60 years. Amongst the earliest work were analytical models developed by Mer- chant [1,2] and Piispanen [3] on the mechanics of metal cutting. These models are known as the shear-angle models in that they provide empirical relations between the shear angle, the rake angle and the coefficient of friction. These models can also be used to estimate forces, stresses, strains, and energy consumption in the metal cutting process under plane strain conditions. More sophisticated shear-angle models were later developed to include the effect of various design para- meters. Lee and Shaffer [4] proposed a shear-angle model based on the slip-line field theory, which assumes a rigid-perfectly plastic material behavior and a straight shear plane. Kudo [5] modified the slip-line model by introducing a curved shear plane to account for the con- trolled contact between curved chip and straight tool face. Palmer and Oxley [6] and Oxley et al. [7] con- sidered viscoplastic conditions and included work hard- ening and strain-rate effects. Doyle et al. [8] studied the effect of interfacial friction between the chip and the tool. Trigger and Chao [9] analyzed the effect of local heating in metal cutting. Among the various numerical techniques for studying metal cutting, the finite element method has been widely applied. The versatility of the finite element method allows it to take into account large deformation, strain