Abstract
Additive manufacturing (AM) is a process of making three-dimensional parts from a digital file layer by layer. One of the most popular methods of additive manufacturing is selective laser melting (SLM), which uses a high-power laser to melt and fuse metallic powder particles together. Thermo-mechanical simulations are important for the successful design and implementation of AM processes, as they can predict potential process-induced distortions and residual stresses to the final parts. We find that SLM can lead to the formation of voids, porosity, and other defects in the final part, which can degrade the mechanical properties. One macro-scale approach to modeling these defects is by using a ductile damage criterion like that developed by Johnson and Cook. To predict this damage in Abaqus Standard, a UMAT subroutine was developed implementing the Johnson-Cook plasticity and damage models. To validate this user-subroutine, mechanical examples of increasing complexity were used. In this work, we couple thermo-mechanical finite element simulations with the Johnson-Cook damage model to study the effects of SLM on the propagation of process-induced damage within a part made of Inconel 718. Overall, the process-induced damage could be significant to failure predictions of a deployed part and is an efficient way of predicting material degradation from manufacture.
