PSI - Issue 41

T.J.S. Oliveira et al. / Procedia Structural Integrity 41 (2022) 72–81 Oliveira et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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5. Numerical torsional analysis 5.1. Stress analysis

τ xy stresses at the adhesive layer mid-thickness are analyzed within the scope of this Section, resulting from the applied torsional loading. Since this study relates to a pure torsional loading,  y stresses are nil and, therefore, this usually important stress component is not considered here. Thus, the influence of the variation of L O , t SE and t SI on adhesive layer τ xy stresses is evaluated. Fig. 8 presents τ xy / τ avg , in which τ avg is the average τ xy along the adhesive layer for the respective L O , as a function of L O . τ xy stress distributions show reduced values at the central overlap region, peaking at the overlap ends. Actually, at the inner overlap, the shear-lag effects are cancelled, leading to a smaller magnitude of stresses (Vable and Maddi 2006, Luo and Tong 2007). The τ xy stresses increase with L O is due to the increasing gradient of longitudinal strains in the adherends, caused by the larger bonded areas and applied loads. However, as the Araldite ® 2015 is a ductile adhesive, it is possible to suffer moderate plasticization and partially absorb these peak stresses. Apart from these facts, there is a clear distinction between stress peaks, where the τ xy shear stresses near x / L O =1 is much higher than the opposite one. This difference arises due to the different cross-sectional areas of both tubes, in which the inner tube has a smaller value. As a result, the longitudinal strain for a given will be higher, and a higher magnitude stress peak will be produced.

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2015 - Lo=20

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Fig. 8 – τ xy / τ avg stresses in the adhesive layer as a function of L O .

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2015-20-2-1 2015-20-2-4

2015-20-2-2 2015-20-2-5

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2015-20-1-2 2015-20-4-2

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c) d) Fig. 9 – τ xy / τ avg stresses in the adhesive layer: L O =20 mm and variation of t SI (a), L O =20 mm and variation of t SE (b), L O =40 mm and variation of t SI (c) and L O =40 mm and variation of t SE (d). 2015-40-2-4 2015-40-2-5 2015-40-4-2 2015-40-5-2