PSI - Issue 41

P.M.D. Carvalho et al. / Procedia Structural Integrity 41 (2022) 24–35 Carvalho et al. / Structural Integrity Procedia 00 (2019) 000 – 000

34

11

6.0

5.0

4.0

3.0

U [J]

2.0

1.0

0.0

0

1

2

3

4

t P2 [mm] SAJ 2015 SAJ 7752 DAJ 1/3 DAJ 1/8

Fig. 9. U for the different joint configurations as a function of t P2 .

Detailed summary of the data is presented in Table 4. For this variable, the SAJ 2015 configuration is always the worst performing, and the DAJ 1/8 configuration typically cannot provide a significant improvement (although a maximum  P m of 135% was found for t P2 =1 mm). Actually, this configuration, due to the small extent of SikaForce ® 7752 on the overlap, cannot accomplish the best results. The best results between all configurations were found for the SAJ 7752 for all t P2 except t P2 =3 mm (  P m =583%, 137% and 279% for t P2 =1, 2 and 4 mm, respectively). The DAJ 1/3 managed the best results for t P2 =3 mm, with  P m =237%. Thus, on account of U , the DAJ technique only has advantage in particular geometries.

Table 4. U and  U summary for the tested joint configurations.

t P2 (mm)

Setup

1

2

3

4

Araldite ® 2015 SikaForce ® 7752

0.37 J 2.55 J (583%) 0.88 J (135%) 1.79 J (380%)

1.67 J 3.95 J (137%) 2.67 J (60%) 3.81 J (128%)

1.65 J 3.9 J (137%) 2.84 J (73%) 5.55 J (237%)

0.76 J 2.89 J (279%) 1.2 J (58%) 2.49 J (227%)

DA 1/8

DA 1/3

4. Conclusions The present work addressed the dual-adhesive technique applied to the strength improvement of T-joints. Validation was initially performed with experimental data for different geometries, namely t P2 . Major P m improvements were found by increasing this geometrical parameter, and the maximum CZM absolute deviations were 4.7% for the 2015 and 7.2% for the 7752, thus validating the CZM methodology for the design of peel-dominant bonded joints. The dual-adhesive showed numerically showed that failure typically took place at the transition between adhesives in the bondline, although variations were found depending on t P2 . The stress analysis showed a slight improvement for the DAJ configuration by reducing peak stress at the adhesive layer edges. The P m and U analyses showed that the DAJ 1/3 is recommended over DAJ 1/8, and that strength improvements can be achieved by this technique over SAJ. Over the T-joint with the 2015, the maximum improvements were 38% for the DAJ 1/3 and t P2 =1 mm ( P m ) and 583% for the SAJ 7752 and t P2 =1 mm ( U ). On the other, considering the U analysis, only for specific t P2 could the DAJ 1/3 perform better than the SAJ 7752. References Adams, R. and Mallick, V., 1992. A method for the stress analysis of lap joints. The Journal of Adhesion 38(3-4), 199-217. Adams, R. D., Adams, R. D., Comyn, J., Wake, W. C. and Wake, W. (1997). Structural adhesive joints in engineering, Springer Science & Business Media.