PSI - Issue 72

A.F.L. Macedo et al. / Procedia Structural Integrity 72 (2025) 61–68

63

the shear modulus ( G ), shear yield strength (  y ), shear strength (  f ), and shear tensile strength (  f ). The DCB and ENF tests were used to determine G IC and G IIC , respectively. Table 1 presents all the collected data for this adhesive.

10 12 14

0 2 4 6 8

[MPa]

0

5

10

15

20

25

ε [%]

-

Fig. 1

Table 1. Properties of the adhesive Sikaforce ® 7752.

Property

7752

Young’s modulus, E [GPa]

0.49±0.09

Poisson’s ratio, 

0.30 a

Tensile yield stress,  y [MPa] Tensile failure strength,  f [MPa] Tensile failure strain,  f [%] Shear modulus, G [GPa] Shear yield stress,  y [MPa] Shear failure strength,  f [MPa] Shear failure strain,  f [%]

3.24±0.48 11.48±0.25 19.18±1.40 5.16±1.14 10.17±0.64 54.82±6.38 2.36±0.17 5.41±0.47 0.19 b

G IC [N/mm] G IIC [N/mm]

a manufacturer’s data b estimated from the Hooke’s law using E and 

2.2. Joint dimensions and procedure Fig. 2 illustrates the geometrical parameters of the SLB test specimens. The characteristics of the DCB and ENF specimens are presented in a previous study (Oliveira et al. 2020) . For the SLB tests, the specimens’ dimensions considered were the average span L =125 mm, the initial crack length a 0 ≈70 mm, the thickness of the adherends h =3 mm, the width B =25 mm and t A =0.1; 0.2; 0.5; 1.0 and 2.0 mm. For each t A , five coupons were tested. The tests were carried out at room temperature and at a speed of 2 mm/min on the Shimadzu AG-X 100, an electromechanical rig equipped with a 100 kN load cell. To measure the crack length ( a ), images of the test were taken every 5 seconds, leading to very precise estimates of a . The resolution of the photographs (20 MPixel) was 0.02 mm/pixel and each measurement was approximated to the nearest 1/8th of a mm mark. The a values were measured manually and correlated with the P-  curve and determine the variables for applying the methods described next.

Fig. 2. Geometric parameters of the tested SLB joints.