PSI - Issue 41

T.J.S. Oliveira et al. / Procedia Structural Integrity 41 (2022) 72–81 Oliveira et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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strain) for the adherends and, for the adhesive, either CPE4 (stress analysis) or COH2D4 cohesive elements (strength analysis). 4.1. Experimental failure modes Visual inspection of the fractured joints revealed that all failures were cohesive in the adhesive layer. Fig. 6 depicts example failures for the joints bonded with the Araldite ® 2015 and L O =20 (a) and 40 mm (b). Thus, in the numerical models, only this failure mode will be equated, as described previously.

Fig. 6 – Example failure modes for the tubular joints bonded with the Araldite ® 2015 and L

O =20 (a) and 40 mm (b).

4.2. Experimental-numerical P m comparison In this section, it is intended to assess the validity of the numerical maximum load ( P m ) results, obtained with the triangular cohesive law, by the comparison with experimental results including two different L O . Fig. 7 presents the experimental and numerical values of P m as a function of L O for the tubular joints bonded with the Araldite ® 2015. The numerical strength predictions reveal that the values obtained by CZM, in regard to P m , are in close agreement with the values obtained experimentally. For L O =20 mm, a 6.1% difference was found between the average of the experimental results and the numerical one, being the values obtained by CZM higher than the experimental average. This is considered an acceptable discrepancy, and in fact it is a very small difference, since the experimental results average is P m ≈27 kN and the numerical result is P m ≈29 kN. On the other hand, the percentile difference between the experimental results average and the numerical predictions is even smaller for L O =40 mm, since it is approximately 2.9%. The experimental results average is P m ≈39 kN and the numerical result is P m ≈40 kN. Despite the small differences observed, which are acceptable in view of experimental processes, the values obtained by the CZM predictions are considered as adequate. Thus, the parametric study that follows will only consist of a numerical analysis, due to the positive results of the validation study.

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P m [kN]

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L O [mm]

Experimental

Numerical

Fig. 7 – Experimental and numerical values of P m vs. L O for the tubular joints with the adhesive Araldite ® 2015.