PSI - Issue 72

P.D.A. da Silva et al. / Procedia Structural Integrity 72 (2025) 52–60

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tensile fracture toughness ( G IC ), while the end-notched flexure (ENF) tests provided the shear fracture toughness ( G IIC ). The density (  ) and Poisson's ratio (  ) are also required for processing the results. While E and G were equalled to their static values, due negligible deviations (Karac et al. 2011), t n 0 , t s 0 , G IC , and G IIC were evaluated as a function of the strain rate by using a logarithmic extrapolation technique. The final properties adjusted for this study can be found in Table 2 (Silva et al. 2022).

Table 1. Mechanical properties of DIN 55 Si7 (Silva et al. 2022). Properties Value Young’s modulus, E [GPa] 210 Tensile yield stress,  y [MPa] 1078 Tensile strength,  f [MPa] 1600 Tensile failure strain,  y [%] 6 Poisson’s ratio, v 0.3 Density,  [g/cm 3 ] 7.8 Table 2 . Adhesives’ mechanical properties (Silva et al. 2022). Adhesive DP 8005 AV138

XNR6852 E-2

Young’s modulus, E [MPa] Shear modulus, G [MPa] Tensile cohesive strength, t n Shear cohesive strength, t s Tensile toughness, G IC [N/mm] Shear toughness, G IIC [N/mm] 0 [MPa] 0 [MPa]

590 159 27.5 36.7

4890 1560 70.2 51.7 0.35

1742 645.2 53.7 45.8 1.68

1.1

6

0.6 1.7

18 1.5

Density,  [g/cm 3 ] Poisson’s coefficient, v

1.06 0.3 a

0.35 b 0.4 c *a - estimated value; b - value supplied by the manufacturer; c - typical value for epoxy adhesives.

2.2. Geometries The Single Lap Joint (SLJ) that validates the numerical model with experiments under impact loads is initially defined. SLJs were manufactured to carry out the experimental tests, in accordance with ASTM D1002 and ISO 4587. The SLJ is composed of two adherends with a length of 120 mm, L O of 25 mm and an adhesive thickness ( t a ) of 0.2 mm. The t p employed is 2 mm. Fig. 1 presents the geometric parameters that define the adhesive joints.

Fig. 1. Geometry of joint used in the experimental test.

The tubular adhesive joints used in the numerical analysis are composed of two overlapping adherends with dissimilar diameters, bonded by an adhesive. The value of L O is 10 mm and the length of the adherends is 60 mm, for a total specimen length of 100 mm. The outer diameter of the inner tube is fixed at 20 mm, t p is 2 mm, and t a is 0.2 mm. Fig. 2 illustrates the tubular adhesive joint used in the numerical analysis.