Alloy Thin Wall Milling Deformation Simulation And Fatigue Life Prediction

Aluminum alloy is an important material widely used in aeronautical and aerospace industry, among which 7075 high-performance aluminum alloy is indispensable raw material for manufacture of large structures of jumbo jets and military aircrafts. However, for a long time, machining deformation during milling has been one of the barriers to manufacture of high-performance aeronautical workpieces for aeronautical industry in our country. To explore mechanism of machining deformation of aeronautical 7075 aluminum alloy workpieces and optimize milling parameters so as to reduce machining deformation, the following work was conducted:1. Finite element model of milling was developed by using MARC. Afterwards, experiment to measure deformation of machined workpiece was performed. Simulation result and experimental result were compared and it is proved that the finite element model is qualified to predict machining deformation;2. By use of the model, simulation was performed to explore deformation process of aluminum alloy workpiece during milling. Besides, simulation was also performed to study influence exerted by various factors such as initial residual stress field, tool path, milling force, fixture tool and different way of release of fixture on machining deformation of the workpiece. The simulation result can be used as reference for industrial manufacture of aeronautical workpiece;3. Preparatory research was conducted on fatigue life prediction of aluminum alloy thin-walled workpiece with initial crack. By using MARC,2D aluminum alloy crack propagation model was developed and relationship between stress intensity factor and crack length was obtained;4.3D crack propagation model for typical aluminum alloy workpiece was developed using FRANC3D and fatigue life of the aluminum alloy workpiece under cyclic loading was predicted by use of the software.