Powder bed properties modelling and 3D thermo-mechanical simulation of the additive manufacturing Electron Beam Melting process

In this work, an improved but still rather simple computational analysis is presented for a more detailed prediction of Electron Beam Melting (EBM) process outcomes. A fully coupled thermomechanical analysis is developed in which nonlinearities due to the variation of material properties when the material melts are included. A new analytical approach is developed to emulate the volume variation of the powder bed during heating and melting. Particularly, the expansion of the powder particles and the porosity reduction within the powder bed are considered simultaneously. The thermal expansion and the shrinkage of solid material during heating and cooling and the stress formation within the solid material are also modelled. The model can predict the geometrical transformation of the powder into solid material in an efficient way. A comparison between experimental and simulated cross-sectional areas of melted single lines is presented. Both continues line melting and fractional line melting, multi beam melting, are considered. The model shows a good ability to provide consistent and accurate forecasts. The maximum deviations between experimental and numerical results are approximately 15% for the height and 5% for the width of the melted lines, respectively. A comparison with a pure thermal model is also included, and benefits and differences between the two models are discussed.