An Euler Graph-Based Path Planning Method for Additive Manufacturing Thin-Walled Cellular Structures of Continuous Fiber-Reinforced Thermoplastic Composites

Thin-walled cellular structures of continuous fiber-reinforced thermoplastic composites (CFRTPCs) have received much attention from both academics and industry due to their superior properties. Additive manufacturing provides an efficient solution for fabricating these thin-walled cellular structures of CFRTPCs. However, the process often requires cutting fiber filaments at jumping points during printing. Furthermore, the filament may twist, fold, and break due to sharp turns in the printing path. These issues adversely affect the mechanical properties of the additive manufactured part. In this paper, a Euler graph-based path planning method for additive manufacturing of CFRTPCs is proposed to avoid jumping and sharp turns. Euler graphs are constructed from non-Eulerian graphs using the method of doubled edges. An optimized Hierholzer's algorithm with pseudo-intersections is proposed to generate printing paths that satisfy the continuity, non-crossing, and avoid most of the sharp turns. The average turning angle was reduced by up to 20.88% and the number of turning angles less than or equal to 120° increased by up to 26.67% using optimized Hierholzer's algorithm. In addition, the generated paths were verified by house-made robot-assisted additive manufacturing equipment.