PSI - Issue 72

L.A.S. Maia et al. / Procedia Structural Integrity 72 (2025) 43–51

49

0.0 0.5 1.0 1.5 2.0 2.5

3.5

1 mm 2 mm 3 mm 4 mm

1 mm 2 mm 3 mm 4 mm

3.0

2.5

2.0

 y /  avg

 xy /  avg

1.5

1.0

-1.5 -1.0 -0.5

0.5

0.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

x/L O

x/L O

a)

b)

Fig. 5. Stress distribution for the DP8005+AV138 combination as a function of t P : a)  xy and b)  y . Relatively to  xy stresses (Fig. 5 a), the results are similar between t P , although peak  xy stresses tend to increase as t P decreases. At the overlap ends, peak  xy stresses increase by reducing t P , leading to the best distribution for t P =4 mm. In  y stress distributions (Fig. 5 b) there is also no symmetry in the stress profiles and a varying trend with t P is also visible. For t P =3 and 4 mm, the inner zone corresponding to the stiff adhesive is mostly under compressive stresses. This difference to the smaller t P results from the higher stiffness of the adherends, which forces the adhesive into a compressive state. Fig. 6 (a) presents P -  curves for the DP8005+AV138 combination as a function of t P , and Fig. 6 (b) the P m data for all adhesive combinations. As shown in Fig. 6 (a), P m increases with t P , while δ max decreases with the same variable. This tendency results from the decrease in adherend deformation by increasing t P , which leads to higher peak  xy stresses in the adhesive. The P m data of Fig. 6 (b) reveals a tendency for the various adhesive combinations, i.e., the P m increases with the increase of t P .

10 12 14 16 18 20

10 15 20 25 30 35 40

1 mm 2 mm 3 mm 4 mm

DP8005+AV138 RTV106+AV138 DP8005+XNR6852

28.29

26.94

26.05

23.97

17.19

P m [kN]

P [kN]

0 2 4 6 8

14.76

14.51

14.35

13.71

11.78

10.84

10.33

0 5

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

1

2

3

4

δ [mm]

t P [mm]

a)

b)

Fig. 6. Numerical P -  curves for the DP8005+AV138 combination (a) and P m for the various adhesive combinations (b) as a function of t P . Table 6 lists E f for all adhesive combinations and t P under analysis. For the DP8005+AV138 combination, increasing t P from 1 to 2 mm translates into a 20 % reduction, while further increasing t P leads to no significant change. The reported E f reduction arises from the reduction of joint deformations, leading to a smaller amount of impact energy being transferred to the adhesive layer. For this combination, the elasticity limits were not exceeded, meaning that there was no plastic deformation of the adherends. In the RTV106+AV138 combination, the joint with t P =3 mm presents higher E f than the joints with t P =2. This behavior is related to  max , which in fact is very close to the 1 mm model. The maximum adherend displacement of 2 mm thickness model was lower than expected giving rise to also lower E f . As with the previous combination, the elastic limits of the adherends were not exceeded and hence no plastic deformation occurred. The DP8005+XNR6852E-2 combination reveals that the results for t P =2, 3, and 4 mm are very close and present lower values when compared to the 1 mm, which is explained by the higher  max for t P =1 mm. In this combination of adhesives, plastic deformation occurred for t P =1 mm (0.17%), which can be considered a very low value and is therefore not believed to have any influence in the performance of the joint.