Dual-wall continuous fiber reinforced cellular structures made by fused filament fabrication

Continuous fiber reinforced cellular structures (CFRCSs) offer advantages in mechanical properties over non-reinforced cellular structures and can be manufactured using the common additive manufacturing method of fused filament fabrication (FFF). However, the single-wall design typically used for CFRCSs could potentially be improved by using a dual-wall (sandwich beam) design within the cellular structure’s walls to increase overall strength and stiffness. Therefore, the purpose of this study is to investigate a novel design for dual-wall CFRCSs. Single-wall and dual-wall CFRCS samples with triangular, square, and hexagonal geometries along with corresponding non-reinforced cellular structure samples with the same wall width were printed using FFF. Initial peak force (IPF)-to-mass ratio and specific modulus under compression were used to measure strength and stiffness, respectively. Single-wall CFRCSs increased IPF-to-mass ratio across geometries (63.2 ± 46.7% change) but overall did not increase specific modulus compared to corresponding non-reinforced samples. Dual-wall CFRCSs increased both IPF-to-mass ratio (81.3 ± 48.6% change) and specific modulus (101.8 ± 39.7% change) across geometries compared to corresponding non-reinforced samples. Dual-wall CFRCSs were shown to more effectively utilize fiber reinforcement than single-wall CFRCSs to improve both strength and stiffness. Furthermore, using a dual-wall design did not significantly change the deformation behavior and relative properties between geometries of cellular structures.