A heterogeneous pore design algorithm for material extrusion additive manufacturing

Material extrusion additive manufacturing offers great potential for customizing matters with complex external contours, and filament diameter-adjustable 3D (FDA-3D) printing strategy provides fresh impetus to create heterogeneous porous structures inside these complex matters. However, the absence of supporting algorithms to implement FDA-3D printing severely hinders its widespread use. In this paper, we develop a heterogeneous pore design (HPD) algorithm aimed at advancing the development of FDA-3D printing for producing heterogeneous porous matters. The HPD algorithm consists of three sub-algorithms: model design, collapse compensation, and fabrication file (G-codes) generation. As proofs of concept, we utilize this algorithm to 3D print radial gradient and letter-embedded gradient materials following specific steps: (1) designing the heterogeneous porous models with collapse compensation in Grasshopper (R) and displaying them in Rhinocores (R); (2) customizing and writing the corresponding G-codes files by following the material extrusion 3D printer's control rules; (3) upgrading a commercial extrusion printer to FDA-3D print the design models via the customized G-codes. Micro-computed tomography-based 3D reconstruction and quantified pore size maps for the fabricated objects demonstrate the high capability of this HPD algorithm. Overall, the HPD algorithm holds the potential to revolutionize material extrusion 3D printers cost-effectively, creating new possibilities for material extrusion of heterogeneous materials.