Path-driven shell lattices designed for continuous fiber composite 3D printing

3D printing of continuous fiber reinforced composites (CFRC) significantly strengthens the mechanical properties of the printed parts. However, design for CFRC 3D printing coupled with continuous path planning is challenging and still underdeveloped, especially for the novel lattice structures. Hence, this work develops a shell lattice design method and a series of 3D shell lattices for CFRC 3D printing. First, the feasibility of fabricating existing shell lattices like triply periodic minimal surface (TPMS) by CFRC 3D printing is discussed. Then, a path-driven shell lattice (PDSL) design method for CFRC 3D printing is presented. The proposed PDSL is constructed from a stack of multi-directional continuous paths defined by a novel periodic function. Both the periodicity and path continuity are guaranteed to enable the continuous fiber deposition. The mechanical properties of the PDSL are optimized with the inverse homogenization method. The surface mean curvatures of the PDSL are optimized with the Surface Evolver to realize a minimal surface with close-to-zero mean curvatures. Finally, both the PDSLs and TPMSs are fabricated by CFRC 3D printing and evaluated by the three-point bending test. The test result demonstrates that the proposed PDSLs realize better mechanical performance under the specific loading condition.