Kink band orientation of 3D printed continuous carbon fiber composites under compressive loading

Abstract

For continuous carbon fiber-reinforced plastic (cCFRP), in the case of loading in the longitudinal direction, occurrence of kink band failure causes compression strength to be lower than the tensile strength. Furthermore, 3D-printed cCFRP may exhibit intrinsic compressive behavior depending on the printing orientation. In this study, two types of rectangular specimens were fabricated using the Markforged Mark Two > 3D printer. The first was the in-plane specimen, whose width direction was parallel to the print bed and thickness direction was along the layup direction. The second was the out-of-plane specimen, whose width direction was the layup direction and thickness direction was parallel to the print bed. Compression tests were performed, and the experimental results were compared. As a result, the compressive strengths of both types were similar, and the kink bands always grew in the lay-up direction. For the out-of-plane specimens, nonlinear stress–strain curves were observed. This may be due to the delamination crack growth caused by the low strength in the lay-up direction and the existence of initial defects. This study experimentally investigated the effect of two different printing orientations of 3D printed cCFRP to its strength and failure mode, and this work shows the importance of considering structural deformation due to compression loading in 3D printed cCFRP.

Keywords:

• 3D printer
• composite materials
• printing orientation
• CFRP
• compression test
• kink band

Acknowledgment

I express my deepest gratitude to them.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Tokyo Institute of Technology [1102202000000000101baeaem2002116].