PSI - Issue 28

I.J. Sánchez-Arce et al. / Procedia Structural Integrity 28 (2020) 1084–1093 Sánchez-Arce et al. / Structural Integrity Procedia 00 (2019) 000–000

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The tensile mechanical properties of the chosen adhesive (Araldite ® AV138) were determined by following the guidelines and dimensions from the NF T 76-142 standard [20]. Adhesive’s shear properties were determined via the thick adherend shear test (TAST) test (ISO 11003-2), as described in previous work [19]. Finally, the adhesive’s mechanical properties were grouped and are shown in Table 1. The mechanical properties mentioned here are necessary for the numerical models described in Section 3.2. Subsequently, single lap joint (SLJ) test samples were prepared by following the ASTM D1002 standard. To obtain strong data for the analysis five samples were prepared for each L O .

Table 1. Mechanical properties of the Araldite  AV138 [19].

Property (unit)

Value

E (GPa)

4.89 ± 0.81

ν

0.35 1

36.49 ± 2.47 39.45 ± 3.18 1.21 ± 0.10 1.56 ± 0.01 25.1 ± 0.33 30.2 ± 0.40

 y (MPa)  f (MPa)

ε f (%)

G (GPa) τ y (MPa) τ f (MPa)

7.8 ± 0.70

 f (%)

1 Manufacturer’s data.

2.2. Joint geometry The SLJ specimens were manufactured following the ASTM D1002 standard using an adherend thickness t P =3 mm, an adhesive thickness t A =0.2 mm, and four L O : 12.5, 25.0, 37.5, and 50 mm (Figure 1). The clamping distance was set to L T =180 mm in all cases. Once all the adherends were cut, their surfaces were prepared by sandblasting the bonding interfaces. These surfaces were later degreased with acetone and the adhesive was applied. The adhesive thickness was controlled by placing calibrated metallic strips between one adherend and the jig (see i.e., [20]). Subsequently, all the specimens were left curing at room temperature for a minimum of 48 hours. Once all the joints were cured, the excess of adhesive was mechanically removed (milling).

Figure 1. Schematic representation of a SLJ and its parameters.

Finally, the tensile properties of the specimens were determined with a Shimadzu AG-X 1000 Universal Testing Machine (UTM) with a 100 kN load cell and using a strain rate of 1 mm/min, as recommended by the standard. The experimental P max was considered as the average of the failure loads of the specimens corresponding to each L O group.