Macro-scale finite element simulation of wire-arc additive manufacturing

Abstract

This paper focuses on the development of a finite element computer software to perform macro-scale thermo-mechanical simulations of wire-arc additive manufacturing (WAAM). The emphasis is placed on various aspects of computer implementation, such as modeling the heat source, incorporating an element birth approach to replicate material deposition, and ensuring compatibility of solution time increments with the wire feed rate, travel speed of the heat source and melt pool volume. Thermal strains are also included due to their impact on residual stresses and distortions of the built parts after finishing material deposition. Experiments consisting of single bead, multi-layer deposition of AISI 316L stainless steel along linear paths are utilized to validate the predicted temperature distribution over time and evaluate the computed geometry and distortions of the deposited vertical walls after unclamping. Microstructure observations of samples extracted from the walls combined with finite element estimates of the temperature gradient help understand the influence of temperature history on the morphology and orientation of columnar grain growth.