Parallel finite element tool to predict distortion induced by initial residual stresses during machining of aeronautical parts

Aeronautical parts are often large and complex monolithic parts machined from rolled plates or forged parts. Nowadays, one of the main objective in the aeronautical manufacturing is to produce light parts with better mechanical properties and therefore more environmentally friendly planes. One way to achieve that goal is the development of new grades and the optimisation of manufacturing processes. The machining process is an essential step in the manufacturing of aeronautical parts where issues can occur. The post-machining distortion due to the re-equilibrium of the initial residual stresses inside the initial workpiece is the main problem which leads to geometrical and dimensional variabilities of parts and then unexpected extra conforming steps. There is therefore an essential need to predict distortions during the machining of large and complex parts to anticipate or avoid additional step. In this paper a new parallel finite element tool is introduced which enables to predict the non-linear behaviour of the workpiece during machining due to its changing geometry resulting from fixture/workpiece contacts. The numerical methods used are described (removal of material approach, parallelization, fixture/workpiece contact) and an example of the simulation of a part machined from a rolled plate is presented. Results obtained are then compared with experimental results, showing a good agreement.