PSI - Issue 68

P.M.D. Carvalho et al. / Procedia Structural Integrity 68 (2025) 398–404 P.M.D. Carvalho et al. / Structural Integrity Procedia 00 (2025) 000–000

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2. Experimental and numerical data 2.1. Materials

Joint fabrication was made using AW 6082-T651, an aluminum alloy. Its mechanical properties were determined to be E =70 GPa (Young’s modulus), n =0.30 (Poisson’s coefficient), s y =261.67 MPa (tensile yield stress), s u =324.0 MPa (tensile strength) and e f =21.70% (tensile failure strain). In previous work (Neto et al. 2012, Campilho et al. 2013, Faneco et al. 2017), the properties of the adhesives used in this work were determined, and are presented in Table 1. Table 1. Properties of the adhesives Araldite ® AV138 (Neto et al. 2012), Araldite ® 2015 (Campilho et al. 2013) and SikaForce ® 7752 (Faneco et al. 2017).

Property

138

2015

7752

Young’s modulus, E (GPa)

4.89±0.81

1.85±0.21

0.493±0.089

0.33 a

0.35 a

0.33 a

Poisson’s ratio, n

3.24±0.5

36.49±2.47 39.45±3.18 1.21±0.10 1.56±0.01 25.1±0.33

12.63±0.61 21.63±1.61 4.77±0.15 0.56±0.21 14.6±1.3 17.9±1.8 43.9±3.4 0.43±0.02 4.70±0.34

Tensile yield strength, s y (MPa) Tensile failure strength, s f (MPa) Tensile failure strain, e f (%) Shear yield strength, t y (MPa) Shear failure strength, t f (MPa) Shear failure strain, g f (%) Toughness in tension, G IC (N/mm) Toughness in shear, G IIC (N/mm) Shear modulus, G (GPa)

11.49±0.25 19.18±1.4

0.188

5.16±1.1 10.17±0.6 54.82±6.4 2.36±0.2

30.2±0.4 7.8±0.7

b

0.20 0.38

b

5.41±0.5 a values provided by the adhesives’ manufacturers, b values obtained by an inverse method.

2.2. T-joint characterization Fig. 1 shows the geometry of the proposed T-joint. The essential parameters (in mm) are: width B =25, flat adherend thickness t P1 =3, curved adherend thickness t P2 =1, 2, 3 and 4, adhesive thickness t A =0.2, curved element free length L A = 60, overlap length L O =25, specimen length L T =100 and curved adherend radius R =5, 5.5 and 7.5. For this work, besides comparing SAJ to DAJ using a joint configuration as showed in Fig. 1, three adhesive configurations are evaluated, namely 2015/AV138/2015, 7752/AV138/7752 and 7752/2015/7752. The DAJ joints will be setup with varying % of L O : DAJ 1/8 (12.5/75/12.5), DAJ 1/4 (25/50/25) and DAJ 1/3 (33.3/33.4/33.3).

Fig. 1. Joint geometry and respective dimensions.

2.3. Experimental procedure Aluminum plates and sheets from 1 mm to 4 mm in thickness were cut to size. t P1 remained 3 mm, and t P2 varied ( t P2 =1, 2, 3, and 4 mm). An increasing R with t P2 , between 5 and 7.5 mm, was used for the 90° bend of the curved adherends. Grit blasting and degreasing with acetone were used to prepare the surfaces where the adhesive was applied. The adhesives were applied on the lower adherends while these were placed on a flat surface. Shims were