Application of hierarchical thermo-mechanical modelling and development of a generalized heat-source trajectory for an aluminium WAAM component

Wire Arc Additive Manufacturing enables cost effective production of metallic components, however accurate prediction of the thermo-mechanical behaviour remains computationally demanding because of complex thermal interactions, repeated heating and cooling cycles and thousands of sequentially deposited beads. This work presents an application of a three-level hierarchical thermo-mechanical modelling framework for WAAM and its experimental validation through the fabrication of an aluminium circular nozzle-like component. The methodology consists of bead layer and wall level analyses, solving the thermo-mechanical phenomena at each stage for the subsequent pass to the next level. the present framework combines transient heat transfer and structural finite element analyses to predict temperature evolution, heat accumulation, residual stress development and geometric distortion throughout the manufacturing process. The complete particular wall level simulation consists of 27 deposited layers comprising 1,431 sequentially activated beads, requiring the solution of approximately 1.7 billion of equations and 1.6 TB output database. A generalized heat source trajectory formulation based on the deposition geometry is introduced to represent transient deposition behaviour. At the bead level, it can be represented by a constant position path, at the layer, by sinusoidal trajectory, and at the wall level, by an oscillated sinusoidal function with progressively decreased amplitude. Experimental validation using a robotic GMAW-CMT WAAM system has demonstrated excellent agreement between numerical and experimental results, with fabricated component closely resemble the desired geometry and temperature peaks deviation of only 1.05 \(\%\) . The developed methodology provides a computational framework for automated WAAM process planning and optimization, establishing a basis for subsequent integration of real-time sensing and closed-loop process control.