PSI - Issue 77

D.C. Gonçalves et al. / Procedia Structural Integrity 77 (2026) 79–86 Gonçalves et al./ Structural Integrity Procedia 00 (2026) 000 – 000

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Fig. 6. (a) DCB nodal discretization; (b) ENF nodal discretization.

The numerical results are presented and compared with the experimental data in Fig. 7. It is noticeable that the three schemes (DBT, CBT and CBBM) used to obtain the fracture energy at the crack tip provide similar approximations in both the Mode I and Mode II scenarios. Regardless of the technique, the numerical model accurately predicts the experimental behaviour of the DCB and ENF adhesive joints. Table 2 presents the maximum failure load values, and the relative error with respect to the experimental data. The experimental values are the average maximum load of all the specimens tested. In the DCB case, the numerical analysis underpredicts the experimental average with a relative error of less than 2%, using the DBT, CBT and CBBM schemes. On the other hand, the maximum load in the ENF case presents an error of about 6% for the DBT and CBT methods, and a smaller 2% error using the CBBM technique. It is also possible to correlate the load and displacement data with the numerical crack length and the crack length measured experimentally. Fig. 8 shows the applied load as a function of the crack length. Notice that the curves initiate at the initial crack length, 0 . Then, the load is increased whilst crack length remains constant, = 0 . Afterwards, the maximum failure load is reached, and the crack tip propagates through the adhesive layer with increasing and decreasing as Fig. 8 shows for the DCB (Fig. 8a) and ENF (Fig. 8b) cases.

(a) (b) Fig. 7. (a) Numerical DCB − curves; (b) Numerical ENF − curves. Table 2. Experimental and numerical maximum load for DCB and ENF test.

DCB [ ] Error [%] [ ] Error [%] - 445.3 - ENF

Experimental

102.4 101.0 100.4 100.4

DBT CBT

-1.33 -1.91 -1.91

474.4 473.1 457.0

6.52 6.23 2.62

CBBM