PSI - Issue 72

C.F.F. Gomes et al. / Procedia Structural Integrity 72 (2025) 34–42

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 y /  avg

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x / L O

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Araldite AV138

Araldite 2015

SikaForce 7752

Fig. 5. σ y / τ avg stress distributions depending on: a) adherend materials; b) L O , and c) type of adhesive. Fig. 5 (b) shows σ y stress distributions of CFRP adhesive joints, bonded with the 2015, as a function of L O (10, 20 and 40 mm). An upward trend is detected in peak stresses with increasing L O . As expected, peak σ y stresses appear at the overlap edges. The transverse deformation of the joint give rise to more significant tensile stresses in these regions. The maximum stresses were obtained for L O =40 mm ( σ y / τ avg =3.08) at x / L O =0 (proximity to the smallest deformed cross-section between the two adherends). Fig. 5 (c) reports the influence of the type of adhesive on σ y stress distributions. For this case, CFRP tubular joints with L O =20 mm bonded with different types of adhesives were analyzed. The results show higher peak σ y stresses in the AV138 compared to the 2015 and 7752. This difference arises from the higher elastic stiffness, which results in higher stress concentration at the overlap edges. The 7752 is the adhesive with the lowest σ y / τ avg stress gradient, since this adhesive has the lowest stiffness between the three adhesives studied. The AV138 showed σ y / τ avg =2.92 while the 7752 only revealed σ y / τ avg =1.07 (peak values along the overlap). 3.2.2. Shear stress Fig. 6 shows  xy stress distributions.  xy stresses have low magnitude at the inner overlap and peak at the overlap edges. These peak stresses arise due to the differential deformation of the tubes along the overlap.

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x / L O CFRP AW 6082-T651 aluminum DIN 55Si7 steel

x / L O

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b)

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 xy /  avg

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Araldite AV138

Araldite 2015

SikaForce 7752

c)

Fig. 6. τ xy / τ avg stress distributions depending on: a) adherend materials; b) L O , and c) type of adhesive.