3D numerical modelling of turning-induced residual stresses – A two-scale approach based on equivalent thermo-mechanical loadings

Abstract

Nowadays, fatigue life of engineering components is a major topic. In the literature, extensive works have been reported in order to assess the machining-induced surface integrity which is known to be a first-order parameter for the fatigue resistance. This paper lies in the framework of turning-induced residual stress prediction by presenting an up-dated method based on a two-scale approach. Previous works aimed at building a 3D hybrid method consist of modelling the turning consequences through equivalent thermo-mechanical loadings combining a finite element model with experimental tests. The new proposed global hybrid strategy keeps the same concept but has the advantage of defining the thermo-mechanical shapes more accurately thanks to local 2D orthogonal cutting models. Moreover, the calibration of the equivalent thermo-mechanical loadings is easier as only turning forces have to be measured, which makes it more accessible to end-users. Finally, the model provides results considering the effective machined surface topography instead of considering a basic flat surface. After carefully detailing each step of the numerical method, a validation case study concerning a longitudinal turning operation on a 15-5PH martensitic stainless steel is proposed. By comparing numerical results with experimental residual stresses coming from X-Ray diffraction, the new numerical method shows its superiority to predict, within few hours, much more accuratly the residual stress state induced by a real longitudinal turning operation.