PSI - Issue 61

João C.M. Santos et al. / Procedia Structural Integrity 61 (2024) 79–88 Santos et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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3.2. Stress analysis The distribution of shear stresses (  xy ) and peel stresses (  y ) in the elastic regime for the different geometries and adhesives is carried out for the sample case of traction loading. It is assumed and verified that the reported tendencies between adhesives and geometries is consistent with those of the different loadings, although with variations in the curves’ shapes. Stresses were taken at the adhesive mid -thickness. All stresses were normalized by the average  xy stress in the adhesive layer (  avg ). The adhesive layer’s length is also normalized, such that 0≤ x / L ≤ 1. Fig. 8 shows  xy /  avg stresses. Peak stresses are visible at the ends of the adhesive joint and nearly nil stresses at the middle, due to the higher adherends’ stiffness at the bond ends. Peak  xy /  avg stresses vary according to the stiffness of each adhesive, with AV138 clearly being the stiffest. The 7752 shows the most uniform distribution of the stresses generated, due to its flexibility. Compared to the A140-1, the percentile reductions of peak values are 28.4% (butt), 9.6% (chamfer 1), and 28.8% (chamfer 2). By considering only the adhesive that reaches the highest stress peaks in each geometry (AV138), compared to the butt geometry, peak  xy /  avg stresses decrease by 42.3% for the chamfer 1 geometry, and increase by 1.1% for the chamfer 2 geometry. Fig. 9 shows  y /  avg stress for the tested adhesives and proposed geometries. Peak stresses are visible at the adhesive layer ends for all geometries. The butt geometry exhibits an opposite trend to the chamfer 1 and 2 geometries, since peak  y /  avg stresses diminish as the adhesive stiffness increases. In this geometry, peak stresses for the AV138 are 9.6% lower than that for the A140-1. In the chamfer 1 geometry, peak  y /  avg stresses for the 7752 are 14.8% lower than that for the A140-1, while in the chamfer 2 geometry, peak  y /  avg stresses’ difference between the same adhesives is 30.3%. Between geometries, for the chamfer 1 and 2 geometries, peak  y /  avg stresses drastically diminish compared to the butt geometry. Moreover, peak  y /  avg stresses are proportional to the ad hesives’ stiffness.

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Fig. 8.  xy /  avg under traction loading: butt (a), chamfer 1 (b), and chamfer 2(b) geometries.