Simulation of distortion due to machining of thin-walled components

Abstract

The distortion of components is strongly related to the residual stress state induced by manufacturing processes like heat treatment, forming or machining. Each process step affects the initial stress state of the following process step. When removing material during machining, the component establishes a new stress equilibrium. Stresses are redistributed causing the component geometry to adjust. Especially for thin-walled components distortion potential is high. Gaining knowledge about the influence of initial loads and the release of distortion during machining processes helps to increase product quality and efficiency. The influences of different initial stress states and different machining parameters on the amount of distortion are examined using both FEM simulations and experiments. A thin-walled T-profile made of aluminum alloy Al 7075-T6 serves as test specimen. A bending process applies a load to initialize a repeatable and defined residual stress state. A groove was machined afterwards into the plastically deformed work piece to trigger stress redistribution and a release of distortion. Different loads with 35 to 45 kN and two different geometries of a groove were used. The amount of initial stress has a significant effect on the distortion potential which could be quantified in the study. Simulations show the same behavior as the experiments and the results match very well especially for a high load.