PSI - Issue 26

Costanzo Bellini et al. / Procedia Structural Integrity 26 (2020) 120–128 Bellini et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Specimens extracted from the produced laminate.

3. Results

After carrying out tests on the several specimens, the results were reported in the graphs for all the types of laminate, and of specimens (short or long), to be analysed. As concerns the flexural strength, so for the long beam, this parameter was calculated from the applied load P, the span length l, the specimen width b and the specimen thickness h through the following relation: = 3 2 ℎ 2 ⁄ (1) The results relevant to the long beam specimens are presented in Fig. 4. It can be noted that the type B specimen, that one with 3 layers bonded with the prepreg resin, was the strongest, while the type C, that presented 5 layers bonded with the structural adhesive, was the weakest; in fact, the former presented a flexural strength of about 670 MPa, while the latter about 510 MPa, so a decrease of 24% was found. Moreover, the data scattering for the four specimens tested for each kind of laminate was quite low; in fact, the coefficient of variation obtained was less than 10% for all the types. Observing the results for the four types of specimen it can be noted that both the adhesive type and the number of layers influenced the flexural strength. In fact, the strength increased with fewer layers and with the prepreg resin used as adhesive.

Fig. 4. Flexural strength of long beam specimens.