Thermal modeling and experimental validation of dot-by-dot wire arc additive manufacturing

This study investigates Dot-by-Dot Wire Arc Additive Manufacturing (DBD-WAAM), a novel variant of conventional Wire Arc Additive Manufacturing, which facilitates the fabrication of unconventional lattice structures. The research employs a combined approach of finite element method (FEM) simulations and experimental validation. FEM was utilized to simulate the DBD-WAAM process, analyzing the impact of key parameters such as idle time and heat input on interpass temperature. The simulation results were validated against experimental data. The heat-affected zone (HAZ) boundaries were identified through optical microscopy and compared with FEM predictions. Furthermore, the simulated temperature distribution was correlated with thermal imaging data recorded during the manufacturing process. Three distinct heat source models–semispherical, linearly decaying, and exponentially decaying–were employed to characterize the spatial distribution of heat input. The semi-spherical heat source model demonstrated superior predictive accuracy for both the heat-affected zone boundary and the temporal evolution of temperature. The findings confirm that the FEM model accurately predicts both the temperature distribution and the HAZ boundaries for DBD-WAAM with a maximum average error of approximately 15% for interpass temperature and 20% for substrate temperature in the worst case scenario. Finally, the study proposes a design curve, providing crucial information for selecting appropriate interpass idle times to ensure optimal thermal control between individual dots, and consequently a better control of the geometry and mechanical properties.