A computationally efficient finite element model of wire and arc additive manufacture

Wire and arc additive manufacturing (WAAM) is an emerging technology which has the potential to significantly reduce material usage and manufacturing time through the production of near net-shape components with high deposition rates. One of the main problems of this process is the residual stresses and distortions of the deposited workpiece. To help understand and optimise the process, finite element (FE) models are commonly used; however, the conventional transient models are not efficient for simulating a large-scale WAAM process. In this paper, the stress evolution during the thermal cycles of the WAAM process was investigated with the help of a transient thermomechanical FE model. It was found that the peak temperatures experienced during the thermal cycles of the WAAM process determine the residual stress of that point. Based on this finding, an efficient "engineering" FE model was developed. Compared to the conventional transient thermomechanical approach, this model can save the computational time by 99 %. This new model produced distortion and residual stress predictions that were nearly identical to the original transient model and the experimental results.