Automated interlaminar reinforcement with thickness directional fiber arrangement for 3D printing

To improve interlaminar tensile strength, we developed a mechanism to automatically embed carbon fiber reinforced polymer (CFRP) and epoxy resin in the thickness direction by modifying a fused filament fabrication (FFF) 3D printer. To verify how the mechanical properties were improved by embedding continuous carbon fibers, CFRP filaments and epoxy resin were manually embedded into polylactic acid (PLA) resin, and tensile tests were conducted. The results showed that when the fiber volume fraction (V_f) was 6.4%, the tensile strength improved by up to 170% compared to the PLA specimen with 100% filling. To automatically embed the CFRP into the structure, we developed a tube pump as a device to pour the epoxy resin and a mechanism to automatically drop the CFRP into the structure, and attached it to the FFF 3D printer. Based on the tensile tests on the specimens made by automatically embedding CFRP and epoxy resin into the structure, we confirmed an increase in strength of approximately 45%, demonstrating the effectiveness of this method.