PSI - Issue 66

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M. Totaro et al. / Procedia Structural Integrity 66 (2024) 205–211

3. Results In this paragraph, results of the experimental tests are first presented from the only mechanical standpoint and then failure mechanisms are analysed with IR Thermography. 3.1. Tensile characterization The stress versus strain curves are shown in Fig. 4 a,b. Multiple tests were conducted, confirming that the results are repeatable. Therefore, only one representative curve for each material is shown. For BFRC, the curve in Fig. 4a does not continuously increase until failure but there is an initial load loss, followed by a clear load drop at 374 MPa, which corresponds to the first delamination. In contrast, as shown in Fig. 4b, that the stress-strain curve for GFRC exhibits a typical brittle behaviour, with an approximate linear region followed by a sudden, catastrophic failure at 295 MPa. Notably, the first load loss for Basalt occurs at around 270 MPa, a lower value compared to the Glass breaking stress. However, in terms of overall strength, BFRC shows better performance with greater elongation, demonstrating more effective energy absorption capacity. In this work, Basalt failure is defined as the stress value that leads to the first delamination, while previous load losses are considered only as initial damage. In the light of this, GFRC and BFRC tensile strengths are reported in Tab.1. This difference is attributed to the two different failure modes, which are analysed using IR Thermography in section 3.2.

Table 1. Results from experimental static tensile tests GFRC

BFRC

Percentage increase (%)

Ultimate tensile strength (MPa)

374 ± 20.2

295 ± 4.7

+26.7%

Fig. 4 Stress/Strain Curve for (a) BFRC (b) GFRC.

3.2. Tensile Failure Analysis Two primary failure events can be identified: the first related to matrix cracking and the second to different fibre failure mechanisms. These events were identified using IR Thermography, which enabled to distinguish them. The colour palette uses ranges from purple to yellow, where the lighter shades correspond to higher temperatures. In the red portions of the curves in Fig. 4a,b , matrix failure is the main damage, appearing as random higher temperature peaks on the specimen surface. The evolution of these random peaks at different time points is shown in Fig. 5a for Basalt and Fig. 5b for Glass, where they appear like lighter violet spots. Since the matrix is the same, similar behaviour is observed for both of them.