Deposition sequence optimization for minimizing substrate plate distortion using the simplified WAAM simulation

Wire arc additive manufacturing (WAAM) is a viable alternative to conventional machining or other additive manufacturing technologies, especially for the production of large, thin-walled components. However, finding the optimal deposition sequence for a minimal substrate plate distortion is challenging due to the vast number of possible sequences. The present study tackles this challenge by exploring three distinct objective functions for predicting distortion using the simplified WAAM simulation (SWS) – a semi-analytical model for the time-efficient estimation of thermal histories in WAAM parts. Using the SWS together with three temperature-based objective functions, distortion scores were calculated for each deposition sequence of a four-sectioned wall geometry. A subset of deposition sequences was then simulated using an experimentally validated thermomechanical finite element (FE) simulation. The correlation between the simulated distortion from the FE model and the distortion score from each objective function was analyzed. The results implied a strong and definitive statistical correlation between the substrate plate distortion and one particular objective function which considers the thermal eccentricity. Subsequently, the wall geometry, together with an additional A-shaped geometry, was manufactured using the best, the worst, and a third deposition sequence. After the WAAM process, the substrate plate distortions were measured using a 3D scanner. The scan results validated the prior optimization, indicating the highest distortion for the worst sequence, the lowest distortion for the best sequence, and a level of distortion in between those extremes for the third sequence. The findings of this article can be utilized for the preliminary selection of deposition sequences of WAAM parts.