Dynamic Loading for Fiber Pullout Interface Strength of 3D-Printed Continuous Carbon Fiber Composites

Abstract

3D printing has emerged as an advanced manufacturing technique for carbon fiber reinforced composites and relevant structures that endure significant dynamic loads in engineering applications. The dynamic behavior of these materials, primarily influenced by the dynamic fiber pullout interface strength necessitates investigation into the rate-dependent fiber/matrix interfacial strength. This study modifies a Hopkinson tension bar to conduct dynamic pullout tests on a single fiber bundle, utilizing a low-impedance bar and an in-situ calibrated semiconductor strain gauge to capture weak stress signals. Stress equilibrium analyses are performed to validate the transient dynamic loading on single fiber bundle specimens. The results reveal that the fiber/matrix interfacial strength is rate-dependent, increasing with the loading rate, while remaining unaffected by the embedded length. Fracture microstructural analyses show minimal fiber pullout due to high interfacial stresses induced by longer embedded lengths. Lastly, suggestions are made for the efficient design of fiber pullout experiments.