Issue 48

F.A.L. Viana et alii, Frattura ed Integrità Strutturale, 48 (2019) 286-303; DOI: 10.3221/IGF-ESIS.48.29 300 as example adhesives. The SDEG variable ranges from 0 (no damage in the CZM law) to 1 (full damage in the CZM law). First, it can be found that damage in the SLJ is symmetric, which agrees with the stress distributions depicted in Fig. 13 (a) and Fig. 14 (a), and shows that cracking initiated simultaneously at both overlap edges. In the DLJ, damage accumulates at the overlap edge in which peak stresses concentrate (Fig. 13 (b) and Fig. 14 (b)). As a result, cracking initiates also at this edge. Between adhesives, more flexible adhesives such as the Sikaforce ® 7752 attain P m with smaller absolute SDEG values, which can be attested by the lighter grey colour in the adhesive, and is justified by the smoother stress plots for this adhesive (Fig. 13 and Fig. 14). a) b) Figure 16 : SDEG variable at P m for the SLJ bonded with the Araldite ® AV138 (a) and Sikaforce ® 7752 (b). a) b) Figure 17 : SDEG variable at P m for the DLJ bonded with the Araldite ® AV138 (a) and Sikaforce ® 7752 (b). Fig. 18 depicts a good correlation on the experimental/numerical P m comparison for the joints bonded with the Araldite ® AV138. Actually, the maximum relative deviation for the SLJ was -5.82%, found for L O =12.5 mm. Moreover, the data shows relative deviations of -2.8, -1.0 and 0.5% found for L O =25, 37.5 and 50 mm, respectively. For the DLJ, the maximum relative deviation was -4.2%, found for L O =12.5 mm. For the other configurations, the obtained differences were 3.4% ( L O =25 mm), 1.3% ( L O =37.5 mm) and 0.2% ( L O =50 mm). Here, the CZM models managed to capture the cohesive failure of the adhesive without adherends’ plasticization for the SLJ, and also the plasticization effect that was found for the DLJ with L O ≥25 mm, and that proved to highly affect failure of this non-plasticizing adhesive. a) b) Figure 18 : Experimental and CZM P m comparison for the SLJ (a) and DLJ (b) bonded with the Araldite ® AV138. Fig. 19, related to the Araldite ® 2015, also presents a good correlation between the experiments and numerical data. In fact, the maximum relative deviation for the SLJ was about 5.2%, corresponding to L O =37.5 mm. With respect to the other L O values, the relative deviations were 4.2, 3.2 and 4.2%, for L O =12.5, 25 and 50 mm, respectively. The DLJ with this adhesive gave the best match to the experimental tests between all adhesives and joint types. The maximum relative deviations were 0.2, 0.9, 2.2 and 3.6%, found for increasing L O between 12.5 and 50 mm. In this case, the adherends’ yielding effect was noted by a smaller extent for the DLJ with L O =25 mm, due to the higher attained P m compared to the joints bonded with 0 5 10 15 20 25 30 0 12.5 25 37.5 50 P m [kN] L O [mm] AV138 Experimental AV138 Numerical 0 5 10 15 20 25 30 0 12.5 25 37.5 50 P m [kN] L O [mm] AV138 Experimental AV138 Numerical