PSI - Issue 82

Sana Ullah et al. / Procedia Structural Integrity 82 (2026) 138–145 S. Ullah et al. / Structural Integrity Procedia 00 (2026) 000–000

140

3

specimen is shown in Fig. 1 (a). Tests were conducted on a universal servo-hydraulic testing machine, MTS810, with a maximum loading capacity of 100 kN, while specimens were equipped with 2 (Axial and Transversal) extensometers to measure longitudinal and transversal strains as shown in Fig. 1 (a). The gauge length of the extensometer used for measuring axial strain was 25mm, and the gauge length of the extensometer for measuring transversal strain was 10mm. Test velocity was set at a rate of 0.2mm/min during tests. A compression test was conducted using ASTM C1358-96 (1996), taking the same layups [C0°] and [C45°] on 6 samples in each layup of CFRP and C/C pyrolyzed samples according to the standard. Here, the total length of the specimen is 120mm, a gauge length of 45mm, an average thickness of 4.71 ± 0.01, and an average gauge width of 9.89 ± 0.09. The geometry of the specimens is shown in Fig. 1 (b). Tests were performed on the same MTS 810 machine using only one axial extensometer, as there was no possibility of attaching a transverse extensometer due to the shorter gauge length (Fig. 1 (b)). Test velocity was set at a rate of 0.2mm/min during tests. During Flexural tests, three-point bending tests were carried out according to the guidelines of the ASTM C1341 00 (2000) on the same two different layups [F0°] and [F45°] on CFRP and pyrolyzed samples. For three-point bending tests, 6 specimens of each layup were prepared using the geometry sketched in Fig. 1(c). Following C1341 standards, the span-to-depth ratio adopted is 16:1 to calculate bending properties by avoiding transverse shear stress. The length of all samples is 95mm, having an average thickness of 4.64 ± 0.05 mm, and an average width of 9.83 ± 0.12 mm. The geometrical sketch of the specimen is shown in Fig. 1 (c). The span length for the chosen specimen length was 80mm according to the standard indications. These flexural tests were performed on the same MTS810 using a fixture that was adjusted in the lower grip of the MTS. In this fixture, three steel rollers, having a diameter of 6 mm, were used as load applicators and supports, and the span length between the two rollers (supports) was set to the selected value of 80mm, as shown in Fig. 1 (c). The test velocity was set to 0.2mm/min.

(a)

(b)

(c)

Fig. 1. Tensile (a), compression (b) and 3 point-bending (c) test configuration and specimen geometry.