3D printing with tension and compaction: prevention of fiber waviness in 3D-printed continuous carbon fiber–reinforced thermoplastics

AbstractThe 3D printing of continuous carbon fiber–reinforced thermoplastics (c-CFRTP) results in fiber waviness and voids that limit mechanical performance. The effects of tensioning and compaction forces during 3D printing were experimentally studied to suppress fiber waviness. A tensioning force was generated along the filament to straighten the fibers by asynchronously controlling the filament feeding and print speeds. A compaction force was applied through the nozzle tip by setting the layer height to reduce the voids. Microscopic images of specimen cross-sections and surfaces indicated a reduction in fiber waviness and voids after these treatments, and three-point bending tests demonstrated improved mechanical properties. This combination of tensioning and compaction forces achieved 28% and 45% higher bending stiffness and strength, respectively. Tensioning and compaction forces are important printing parameters for the 3D printing of high-performance c-CFRTP.Keywords: Polymer-matrix compositesmechanical propertiesmechanical testing3D printing Disclosure statementNo potential conflict of interest was reported by the authors.Data availability statementThe data that support the findings of this study are available from the corresponding author, N. Ichihara, upon reasonable request.Additional informationFundingThis work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. 22K20415). The synchrotron radiation experiments were performed at BL46XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2018B1842).