Simulation of welding and stress relief heat treating in the development of aerospace components

Abstract: It is important to control critical dimensions of aero engine components during the manufacturing process in order to maintain the quality. However, there is also a need for reduced lead-time and cost. Simulation can be a tool to achieve this. It can give information about dimension, shape, and residual stresses after each manufacturing process. The objective of the work presented in this thesis is to develop an efficient and reliable method for simulation of welding and heat treatment by using finite element analysis. The simulations will be used for designing and planning the manufacturing processes in order to obtain an acceptable final shape of the component and a robust manufacturing process. An experimental set-up has been developed to evaluate the accuracy of simulations models used in welding analysis. Experiments show that the models can be used in the preliminary manufacturing preparations, in order to evaluate fixture set-ups and process parameters for welding qualitatively. A reliable simulation method can not be achieved if not the process parameters are closely coupled to the simulation model. The stress relief heat treating process in a gas cooled vacuum furnace can be simulated by using radiation boundary conditions for the heating sequence. By using computational fluid dynamics is the estimation of the heat transfer during the cooling stage of the heat treatment process improved. These conditions are strongly dependent on the position of the component in the furnace. There are also large differences in heat transfer coefficient on the individual surfaces on the component.