PSI - Issue 68

M. Totaro et al. / Procedia Structural Integrity 68 (2025) 197–204

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M. Totaro et al. / Structural Integrity Procedia 00 (2025) 000–000

Fig. 1. (a) Front and back of BFRC specimen; (b) Experimental setup.

2.2. Specimens preparation The panel was provided by the Intermarine shipyard located in Sarzana, Italy, and it is made of vinylester resin reinforced with BF. The basalt fibre reinforcement is FILAVATM, a high-performance material created by ISOMATEX, woven into a double-weave Panama-pattern. For the matrix, Atlac® 580 AC 300 vinylester resin was selected, combined with a NOROX® catalyst. The manufacturing technique used for the panel is vacuum infusion, a process favoured for its ability to create laminates with superior mechanical properties with reduced void content and higher fibre volume fractions. The resulting composite laminate measures 1 m x 1 m and consists of six layers of woven fabric with an areal density of 1100 g/m² and a nominal thickness of 5.5 mm. Once fabrication was completed, rectangular specimens (Fig. 1a) measuring 25 x 250 mm² were cut using a band saw for the experimental tests described in Section 2.3. 2.3. Experimental tests The experimental tests consist of static tensile and stepwise fatigue tests, according to ASTM D 3039/D 3039M standard. During the tests, the surface temperature of the specimen was monitored using an IR camera FLIR SC640. Static tensile tests were performed under displacement control, with a crosshead speed of 2 mm·min -1 , using a servo-hydraulic loading machine MTS 810, shown in Fig. 1b, with a maximum load capacity of 250 kN. Typically, to apply the STM, the maximum value of a rectangular area selected on the specimen is recorded and processed using a rlowess filter. This is due to the fact that, in most materials, the most stressed point remains constant throughout the entire test, and failure initiates from this point. However, when the same method was applied to composites, the signal was much more erratic. The maximum damage, corresponding to the hottest point, occurred in random locations that continuously changed during the test. As a result, a statistical analysis was performed to determine where the highest percentage of failure occurred on the specimen, and the thermal behaviour was evaluated within that region. Stepwise fatigue tests were performed using the same loading machine with a stress ratio of R= 0.1 and a testing frequency of 10 Hz. Each step consisted of ΔN= 20.000 cycles, with the load being increased by Δσ= 10 MPa at each step, continuing until failure. In this case, the maximum temperature on the specimen surface was evaluated.