PSI - Issue 33

R.V.F. Faria et al. / Procedia Structural Integrity 33 (2021) 673–684 Faria et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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avoiding the singularities and serving well for comparison purposes (Fernandes et al. 2015). All stress curves are normalized by the average σ y stress ( σ y avg ) along L for the respective joint type. Additionally, the overlap ( x/L ) is also normalized (see Fig. 1), and the stress curves are truncated to only show the vicinity of x / L =0.

300

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 y /  y avg

 y /  y avg

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x / L

x / L Bonded

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b) Fig. 5. σ y stresses for the bonded (a) and welded and hybrid joints (b). Spot-welded

Hybrid

Fig. 5 (a) relates to σ y stresses for the bonded T-peel joint, and significant σ y peak stresses can be found at the vicinity of x/L =0 (loaded end of the adhesive layer), corresponding to the site of crack initiation. The σ y peak stress was 95.68. Fig. 5 (b) shows the same stress plots for the purely welded and hybrid joints. In this plot, the y-axis is also cut to improve visualization of the relevant parts. σ y / σ y avg reaches numbers as 736.63 (tension) and 565.50 (compression) at the weld-nugget edges in the welded joint. In the hybrid joints, σ y peak stresses arise at x/L =0, with a maximum of σ y / σ y avg =95.31. 4.3. Experimental T-peel joint evaluation Fig. 6 compares the experimental P m for all joint types. Between the bonded and hybrid T-peel joints, the hybrid configurations give a major improvement in P m . Comparing with the purely welded joint, having P m =3.5 kN, P m for the bonded joint reduced 64.8%. The performance reduction in the bonded joint is caused by premature adhesive failure at the loaded bonded end (at x / L =0) when compared to the weld-nugget fracture for much higher P m .

Fig. 6. P m comparison for the three joint types.

P m for the T-peel bonded joint with the Araldite ® 2015 only attained 1.21 kN. On the other hand, the comparative evaluation between the purely welded and hybrid joints shows a 40.3% P m improvement for the hybrid joints, which is significant. This difference in behavior takes place because the hybrid joint has improved stresses distributions, compared to the purely welded joint. Moreover, at the same time it enables additional load transfer paths between the two adherends, around the weld-nugget, now contributing to P m (Fig. 5). It should also be emphasized that the ductility of the selected adhesive for the hybrid joint is also an important factor for higher P m , in light of the discussed phenomena for the bonded joint, related to the stress distributions (Fig. 5). It is thus considered that