A novel analytical modeling for prediction of residual stress induced by thermal-mechanical load during orthogonal machining

Abstract

Residual stress on the surface and subsurface has a great influence on the distortion and fatigue life. Rapid and accurate prediction of residual stress is important for the optimization of the machining process in intelligent manufacturing. A novel analytical model is proposed based on the equivalent stress method in this paper. The nonlinear flow characteristics of the work-piece material in the tool-work-piece contact surface and thermal-mechanical coupling effect are fully considered. A new cutting force prediction model was established and the relative errors are within 12%, which verifies the accuracy and the effectiveness of the model for further application to residual stress prediction. The thermal-mechanical conditions of the primary shear plane and machined surface are revealed based on the equivalent stress method. Then, internal stress of work-piece is caused by mechanical load and thermal load obtained on account of linear elasticity theory and heat-elastic-plastic mechanics theory. The predicted residual stress profiles have a high degree of consistency with measurement results of orthogonal turning of 20Cr2Ni4A alloy steel. Prediction accuracy of surface residual stresses was 11.3%, 12.2%, and 12.7% for the condition of v = 24 m/min, ap = 0.1 mm; v = 36 m/min, ap = 0.2 mm; v = 48 m/min, ap = 0.3 mm respectively. The predicted results of the maximum compressive stresses and DMCS are also acceptable. Ultimately, the residual stress profiles obtained from proposed model were reliable. The proposed model has high computational efficiency and provides a new idea for the analytical prediction of residual stress. And the proposed model can be used for further residual stress analysis and prediction of 3D cutting process.