PSI - Issue 80

Seiji Mitsubayashi et al. / Procedia Structural Integrity 80 (2026) 423–430 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

426

4

Fig. 1. (a)Jig for Edge Crack Torsion (ECT) test; (b) Loading and boundary conditions.

2.5. Evaluation of mode interlaminar shear strength of CFRTP In this study, the interfacial shear strength was evaluated using a fragmentation test. A schematic of the fragmentation test setup is shown in Figure 2. A miniature tensile tester was mounted on the microscope stage, and the specimen was placed with a gau ge length of 40 mm. To apply a tensile load of 2 mm, the screw was slowly turned twice. The specimen was then observed using a polarized optical microscope (CX31, OLYMPUS). Images obtained from the observation were analyzed using image processing software (ImageJ) to measure the fragment lengths of the carbon fiber (CF). The interfacial shear strength τ [MPa] was calculated using the method proposed by Feih et al. (2004), as shown in Equation (4): = 38 (4) where l [μm], σ [MPa], and d [μm ] denote the fragment length, the tensile strength, and the diameter of carbon fiber, respectively. Here, the tensile strength of the carbon fiber was assumed to be 3530 MPa, as specified in the manufacturer's catalog.

Fig. 2. Fragmentation equipment.