PSI - Issue 41

J.E.S.M. Silva et al. / Procedia Structural Integrity 41 (2022) 36–47 Silva et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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20°, 15°,10° and 3.43°, and whose effect on different variables such as damage in the adhesive layer, P m , and U , were assessed.

Fig. 2 – Schematic representation of the TSJ.

2.2. Materials The adherends for the TLJs were designed with AW6082-T651 aluminium alloy. This alloy was characterised in previous studies (Campilho et al., 2011c), where the following mechanical properties were determined: tensile strength of 324.00±0.16 MPa, Young's modulus of 70.07±0.83 GPa, tensile yield stress of 261.67±7.65 MPa, tensile failure strain of 21.70±4.24%, and Poisson’s ratio of 0.33. The respective stress -strain curves (  -  ) were experimentally obtained according to the ASTM-E8M-04 standard. The selected adhesive for this work is the Araldite ® 2015, which is considered a moderately ductile epoxy-based adhesive. The Araldite ® 2015 adhesive was characterised in previous work (Campilho et al., 2013) and the determined mechanical and fracture properties are presented in Table 1. The tensile mechanical properties ( E ,  y ,  f and  f ) were obtained through experimental tests performed in bulk specimens. Thick-adherend shear tests (TAST), employing steel adherends, were used to assess the equivalent shear properties. The tensile toughness or fracture energy in pure mode I ( G IC ) was obtained by the double-cantilever beam (DCB) test, and the shear toughness, or fracture energy in pure mode II ( G IIC ), was determined by the end-notched flexure (ENF) test.

Table 1 – Mechanical and fracture properties of the Araldite ® 2015 (Campilho et al., 2013).

Property

Araldite ® 2015

Young’s Modulus, E (GPa)

1.85 ± 0.21

Poisson’s ratio, ν

0.33 a

Tensile yield stress, σ y (MPa) Tensile strength, σ f (MPa) Tensile failure strain, ε f (%) Shear modulus, G (GPa) Shear yield stress, τ y (MPa) Shear strength, τ f (MPa) Shear failure strain, γ f (%) Toughness in tension, G IC (N/mm) Toughness in shear, G IIC (N/mm)

12.63 ± 0.61 21.63 ± 1.61 4.77 ± 0.15 0.56 ± 0.21 14.60 ± 1.30 17.90 ± 1.80 43.90 ± 3.40 0.43 ± 0.02 4.70 ± 0.34

a manufacturer’s data

2.3. Experimental procedure Regarding the TLJs used for the CZM validation process, the substrates were machined from aluminium round stock following standard practices (Krar et al., 2011). Then, surface preparation started with the roughening of the surfaces by grit blasting with corundum sand, followed by cleaning with a degreaser. Three equally spaced nylon