A new approach to deformation control of aeronautical monolithic components of aluminum alloy plates based on stress inverse and stress evaluation

Abstract

In the high-speed machining process of aeronautical monolithic component, the release of residual stresses is a crucial factor of machining deformations with the material removal of 7075 aluminum alloy thick plates. Therefore, the investigation on the evolution mechanism of machining deformation with residual stress release is crucial for machining quality control. It is vital to achieving a high-efficiency and precise machining process. In this work, the bending deformation theory is employed to formalize the mechanical model of machining deformation, which is influenced by the removal of materials. The finite element method is used to calculate the unit deformations by producing the unit stresses in each layer of the aluminum alloy thick plate. The unit force method is established so that the mechanical model of machining deformation can decompose to be multiple of deformation factor with residual stress. Further, by considering the self-equilibrium of residual stresses, the specification model of residual stresses is proposed based on the fact that the machining requirement represents the control limit of machining deformation. By introducing a new unit variable, the sandwich theorem is employed to convert the specification model into the linear homogeneous inequalities. Therefore, the pivot transformation method is suggested to solve the residual stresses in the specification model. Finally, by representing an arbitrary variable as a difference between two non-negative variables, the linear programming method is proposed to judge whether the measured blank initial residual stress is a solution of stress specification. This can evaluate machining deformation within the machining requirement. The active evaluation of residual stresses, which is deduced from the passive analysis of machining deformations by unit force method and pivot transformation, can provide the proper stress specification for the upper of the machining process. Obviously, the stress specification plays a very important role in the bridge between the blank manufacturing and the machining process.