PSI - Issue 77

P.D.A. da Silva et al. / Procedia Structural Integrity 77 (2026) 103–110 Silva et al. / Structural Integrity Procedia 00 (2026) 000–000

109

7

Table 4 shows E a and ∆ E a for the three adhesives as a function of θ . The influence of the adhesive on E a between joints with the same value of θ is negligible. The biggest differences between the three adhesives over θ =90º were - 50.7%, -48.4%, and -36.3% for AV138, DP8005 and XNR6852 E-2 respectively. 3.2.3. Adhesive fillet The adhesive fillet consists of introducing a portion of adhesive at the ends of the adhesive layer. Fig. 8 presents σ y and τ xy stresses for the joints bonded with the AV138. For the AV138 (Fig. 8 a), the adhesive fillet implies a lower concentration of σ y / τ xy stresses at the ends of the adhesive layer, with minor advantage for smaller β . The maximum stress reductions, between β =90º and β =0.5º, were -14.5% (AV138), -9.2% (DP8005), and -13.8% (XNR6852 E-2). At the fillet, σ y / τ avg stresses also diminish for smaller β . τ xy / τ avg stresses of Fig. 8 (b) reveal that the adhesive fillet reduces peak τ xy / τ avg values at x / L O =0 and 1, by an identical percentile amount irrespectively of β . These reductions achieved a maximum (between β =90º and 7.5º) of -11.1% (AV138), -5.6% (DP8005), and -10% (XNR6852 E-2).

1.5

1.5

1

1

0.5

0.5

τ xy / τ avg

σ y / τ avg

0

0

-0.5

-0.5

-0.25

0

0.25

0.5

0.75

1

1.25

-0.25

0

0.25

0.5

0.75

1

1.25

x / L O 7.5 15 30 45 60 90

x / L O 7.5 15 30 45 60 90

a)

b)

Fig. 8. σ y and τ xy stresses at the AV138 adhesive layer midline with fillet.

80

80

60

60

40

40

P m [kN]

P [kN]

20

20

0

0

0

0.2

0.4

0.6

0

20

40

60

80

100

β [º] AV138 DP8005 XNR6852 E-2

δ [mm] 7.5 15 30 45 60 90

a)

b)

Fig. 9. P- δ curves for the AV138 joint with fillet (a) and evolution of P m for all adhesives (b).

Fig. 9 (a) shows the P- δ curves for all joints, with the variation of β for the AV138. β significantly influences P m , as well as δ at failure. The lower the value of β , the higher the value of P m , and the greater the failure δ , irrespectively of the adhesive. According to the analysis of Fig. 9 (b), the joint with β =7.5° obtained the highest failure δ and P m , with gradually increasing values starting from β =90º. The improvements from β =90º to β =7.5º were 73.6%, 19.8%, and 38.7% for the AV138, DP8005, and XNR6852 E-2, respectively. Between adhesives, the most modest results correspond to the DP8005. The relative differences for the other adhesives were between -5.9% ( β =90º) and -32.6% ( β =7.5º) for the XNR6852 E-2, and between -14.6% ( β =90º) and -66.0% ( β =7.5º) for the DP8005. Table 5 summarizes E a and ∆ E a over the joint with β =7.5º. The areas of the P- δ curves for lower β are larger, implying that these joints have more capacity to absorb more impact energy. The joints reveal gradually increasing E a by reducing β , up to +340.6% (AV138), +76.7% (DP8005), and +328.2% (XNR6852 E-2), between β =90º and 7.5º. The biggest differences were found for the XNR6852 E-2 and AV138, which higher P m and failure δ , over the DP8005.