Several standardized methods exist for measuring the compressive strength of CFRP. When unidirectional fibers in CFRP are compressed, some fiber clusters often form kink-bands, where the fibers buckle in an "s" shape. The formation of kink-bands is thus a key factor in determining compressive strength. However, in-situ observation of kink-band initiation within CFRP remains challenging. We developed a method to evaluate the compressive strength of carbon monofilaments using a miniature cruciform specimen. This specimen, about 1 mm wide and 0.1 mm thick, was originally used to assess interfacial tensile strength in prior studies. In some of our tests, compressive failure in carbon monofilaments was observed, attributed to Poisson-induced deformation. In this study, we applied the cruciform test to examine cluster failure of carbon fibers embedded in resin and compared their compressive strength with that of monofilaments.
Tanaka et al. (Wed,) studied this question.