Abstract: Additively manufactured continuous carbon fiber reinforced polymers (C-CFRP), known for their high design flexibility, have achieved rapid development; however, detailed studies on their intralaminar fracture performance remain lacking. In this study, compact tension (CT) and compact compression (CC) tests were conducted on additively manufactured C-CFRP specimens with a [0/90]_4S layup. Failure mechanisms were characterized using X-ray computed tomography (CT) and scanning electron microscopy (SEM). The results indicate that the tensile critical energy release rate ranged from 9.50 to 21.41 kJ/m², while the compressive critical energy release rates range from 22.18 to 188.97 kJ/m². SEM analysis reveal that the microscopic failure mechanisms in tensile fracture included fiber breakage, fiber pull-out, and interfacial debonding, with evidence of fiber bridging during the tensile process. Notably, X-ray CT results show the presence of compressive failure modes at the end of the compact tension specimens. Fiber bridging and end compressive failure contribute to an increase in tensile fracture toughness with increasing crack length. During compressive fracture, the macroscopic failure modes include buckling and compression-shear failure. As the fractured material retained load-bearing capacity during compression, the compressive fracture energy also increases with increasing crack length. This study enhances the understanding of tensile and compressive fracture behaviors of additively manufactured C-CFRP and provides reliable fracture parameters for simulating these materials.

Key words: 3D-printed, C-CFRP, fracture toughness, compact tension, compact compression