Prediction of residual stress and deflection in multi-process milling of large thin-walled components with initial bulk residual stress

Large thin-walled aluminum alloy frame beam structural components are widely used in the aviation manufacturing industry. During the machining process, the initial bulk residual stress and the machining-induced residual stress are introduced, resulting in complex stress redistribution and deformation of structural components. Therefore, to quickly and accurately simulate the residual stress and deformation after multi-process, the influence of each variable is quantified. This paper proposes a residual stress and deflection prediction method for multi-process milling frame beam thin-walled structural components. Combined with the improved element birth and death method (the real simulation of material removal by applying thermo-mechanical loads and the "killed" element, it is fast and suitable for large components.) and the chip formation method (the realistic simulation of tool-workpiece interaction to generate chips and form parts, it is high precision.), the final residual stress and deformation of multi-frame structural components and their local thin-walled feature are predicted. The results show that the prediction errors of the final residual stress, local deformation, and overall deflection are 12.7 %, 16.9 %, and 18.6 %, respectively. Considering the initial bulk residual stress of the blank and thermomechanical load in the model, the RS prediction error can be reduced by 21.1 %, which means that the prediction accuracy of the model is improved. Considering the semi-finishing process, the residual stress can be reduced by 24.1 % and the deformation can be reduced by 31.7 %. The final deflection of the component can be reduced by 58.85 % by releasing the clamping after the removal of each layer of material, which means that the machining accuracy is significantly improved. This study provides a feasible method for the final residual stress and deflection prediction of multi-process milling of large thin-walled frame beam structural components, and a basis for the control of milling deformation of thin-walled feature is offered.