WrapToR Truss Joints: Path Planning for Three Dimensionally Wound Joint Structures With Manufacturing Constraints

Wrapped Tow Reinforced (WrapToR) truss structures are a unique class of truss beams fabricated from composite materials via a modified filament winding technique. While past studies have highlighted their weight advantages over traditional tubular composites, there’s growing attention towards their integration into Hierarchical Space Frames (HSFs), facilitating greater geometric flexibility for diverse applications. Central to this idea is the need for an efficient joining technology. This study introduces a concept employing a 3D version of the WrapToR winding method to generate optimal lattice joint designs. As designing winding paths for intricate joints involving varying numbers of trusses and angles is challenging, this paper presents a path planning algorithm underpinned by graph theory and manufacturing constraints. Primary considerations include tow continuity, geometric limitations, and issues arising from filament overlap and interference in 3D space. The proposed method involves identifying edges and nodes, prioritising them based on a dominance algorithm to minimise interference, and subdividing the problem into manageable sub-graphs. These are tackled using an adjusted graph theory technique, with the global solution being a combination of these sub-graphs, which can be wound in turn. To validate the methodology, specimens of 3-truss and 4-truss joints were path=planned and fabricated, underscoring the viability of the proposed approach.