PSI - Issue 54

D.F.T. Carvalho et al. / Procedia Structural Integrity 54 (2024) 398–405 Carvalho et al. / Structural Integrity Procedia 00 (2019) 000 – 000

404

7

justification is the lack of adherend plasticisation for the previous configuration, as shown in Fig. 4. The differences are quite minor for other L O values. a) b)

50

50

40

40

30

30

U [J]

U [J]

20

20

10

10

0

0

12.5

25

37.5

12.5

25

37.5

50

50

L O [mm]

L O [mm]

AV138

AV138

2015

7752

2015

7752

2015-AV-2015

2015-AV-2015

7752-2015-7752 7752-AV-7752

7752-2015-7752 7752-AV-7752

50

40

30

U [J]

20

10

0

12.5

25

37.5

50

L O [mm]

AV138

2015

7752

c)

2015-AV-2015

7752-2015-7752 7752-AV-7752

Fig. 4. Numerical U for the SAJ and either the 12.5/75/12.5 (a), 25/50/25 (b) or 33/34/33 (c) DAJ configurations.

4. Conclusions In this work, a numerical and experimental study of aluminium stepped adhesive joints was carried out considering the dual-adhesive methodology. Three structural adhesives were used Araldite ® AV138 (brittle), Araldite ® 2015 (moderate ductile) and Sikaforce ® 7752 (ductile). The numerical work was performed in the Finite Element software Abaqus ® that has already built-in the cohesive zone model (CZM) for damage onset and propagation. Regarding the numerical validation it can be settled that for P m comparison, between the numerical and the experimental results, in the case of the tested DAJ, for the 7752-AV-7752 DAJ with L O =12.5 mm, the maximum difference 9%. The CZM approach was therefore validated, enabling the numerical analysis that was subsequently carried out. In terms of joint strength prediction, the DAJ technique revealed significant improvements over the benchmark SAJ, and the recommended configuration for each L O was always a DAJ solution, although the difference from the best SAJ may not be significant. In addition, for larger L O s, the failure of the adherent may minimise the difference in P m . The greatest difference observed between the proposed solutions and the optimal SAJ was 22.9%. When analysing the failure energy, it was found that the DAJ/SAJ differences were higher for the 12.5/75/12.5 and 25/50/25 configurations. Nonetheless, in some configurations, with smaller L O , SAJ presents higher U than all the DAJ. However, for larger L O , the DAJ technique was, in some cases, superior (178.8%) for DAJ 12.5/75/12.5, L O =37.5 mm and 7752-AV138-7752 DAJ when compared to the SAJ 2015 case. References

Adams, R. D., Comyn, J. and Wake, W. C. (1997). Structural adhesive joints in engineering. London, United Kingdom, Chapman & Hall. ASTM-E8M-04 (2004). Standard test methods for tension testing of metallic materials [Metric]. West Conshohocken, PA, ASTM International.