Design and validation of 3D self-supporting structures and printing paths for multi-axis additive manufacturing

Additive manufacturing (AM) has become a widely used tool for fabricating components with complex geometries. However, the overhang effect induced by gravity often necessitates additional supports to prevent collapse and warping during the printing process. To address this issue, previous studies incorporated overhang constraints to the topology optimisation to create self-supporting structures. Nevertheless, these studies primarily focused on 3-axis AM, which deposits material in a single direction and often compromises structural stiffness to achieve self-supporting designs. In response, this study aims to design 3D self-supporting structures tailored for multi-axis AM. By leveraging the rotatable base platform of multi-axis systems, this approach automatically identifies optimised local build directions and the corresponding structural topology to minimise overhangs. The effectiveness of this approach is demonstrated through several numerical examples, with results validated numerically via printing simulations in VERICUT and physically using a multi-axis Wire Arc Additive Manufacturing (WAAM) machine. The results indicate that the performance degradation caused by 3-axis-based overhang constraints can be reduced to a negligible level with the multi-axis-based approach.