Analyzing distortion of aircraft Structural part in NC machining based on FEM simulation

NC machining distortion theory is studied by analyzing the typical aircraft wing rib aluminum alloy structural part. The reasons which lead to machining distortion are accounted for. The research method and process of theoretical model, finite element analysis and milling experiment are presented. The effect of residual stresses on machining distortion which distribute in the aircraft structure part is analyzed. The initial residual stress distribution which generated from material heat treatment is simulated by using thermal-mechanical coupling analysis of the FEM software. Cutting simulation is executed by exploiting the static element deactivation technique. The element is deactivated via Birth/Death feature in ANSYS software. The distortion results generated by the machining simulation are compared with the actual machining data. It appears that both distortion trends are consistent. The validity of the analysis method and the finite element analysis model is verified. Several methods which can be used to predicting and controlling machining distortion are proposed.