NUMERICAL MODEL DEVELOPMENT FOR LARGE-SCALE PART DISTORTION IN WIRE ADDITIVE MANUFACTURING

Additive Manufacturing (AM) technologies are used in several fields like aerospace and automotive industries, medical, architecture and many more, and their benefits, widely known, include customization, complexity without added cost, reduced material waste, and efficient prototyping. Despite various advantages, a major problem that limits the wider application of AM is part thermal deformations, that results in parts not being dimensionally complaint; implying the possibility of required iterative trials to obtain the expected results. As a solution, forecasting of deformations can overcome this problem; in fact providing accurate prediction during simulation-phase of the project, gives the opportunity to take actions to correct or alleviate the effects e.g. through adjusting printing parameters, geometry, supports and so on. This thesis focuses on investigating numerical method for distortion prediction of additive parts. In particular, the aim is to study an inherent strain-based model to simulate large parts distortions in wire additive manufacturing. The goal is to obtain fast and simple model that can yield acceptable accuracy as well as capture the trends and areas of significant distortion. This model is used to analyze axisymmetric geometries, with sensitivity study on geometric parameters and method's coefficients, and then validated against real case studies. The model is developed for wire direct energy deposition (DED) processes, and it gives the freedom to consider the differences between powder-bed and wire AM process and moreover it gives a chance to adapt to its distinctive manufacturing strategies. Furthermore, to make the model usable to different geometries with hundreds of layers, the set up is automated with suitable scripts, making the analysis of large-scale parts easier and without time-consuming activities. In order to validate the proposed model, two actual additive prototype parts are analyzed, that represent low pressure turbine casings (LPTC); for these prints, the actual deformations are available, thus allowing the comparison of the simulated deformation to the actual behavior of the part to be made.