PSI - Issue 64

Yuan Xu et al. / Procedia Structural Integrity 64 (2024) 1865–1872 Author name / Structural Integrity Procedia 00 (2019) 000–000

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3.3. Parametric analysis Fig. 8 shows the effect of variables on the SCF reduction coefficient ψ , including the prestressing level, the CFRP width, the CFRP layers, and CFRP configuration.

a

b

c

p = 50%

d

0.2 0.4 0.6 0.8 1.0 0

w = 20 mm, n = 2 w = 40 mm, n = 1 w = 20 mm, n = 3 w = 60 mm, n = 1

ψ

Max

Saddle Crown

Fig. 8. Effects of variables on the SCF reduction coefficient. (a) prestressing level (p) versus ψ; (b) CFRP width (w) versus ψ; (c) CFRP layers (n) versus ψ; (d) CFRP layers (n) and width (w) versus ψ.

3.3.1 Effect of the prestressing level Fig. 8(a) displays the effect of the prestressing level on the SCF reduction coefficient ψ at various positions along the weld toe. Three different values (0, 25%, and 50%) were assigned to the prestressing level. The relationship between ψ and the prestressing level was approximately linear. For the specimen with non prestressed CFRP, the effect of CFRP strengthening on ψ was limited. With increase of the prestressing level, a noticeable reduction of ψ was observed at each position, especially at the saddle point where the value of ψ decreased from 0.95 to 0.54. Moreover, at the position of maximum hot spot stress, the value of ψ also decreased from 0.96 to 0.75. It was because prestress changed the distribution of hot spot stress along the weld toe and mitigated parts of the external load, thus enhancing the reliability of T-joints. 3.3.2 Effect of prestressed CFRP layers and width This section investigated effects of the CFRP width (20 mm, 40 mm and 60 mm) and CFRP layers (1, 2 and 3) on the SCF reduction coefficient ψ , as shown in Figs. 8(b) and 8(c), respectively. It was observed that the value of ψ was reduced at each position with increase of CFRP width and CFRP layers. For example, under 50% prestressing level and one layer of CFRP, the value of ψ reduced from 0.77 to 0.40 at saddle point with increase of the CFRP width from 20 mm to 60 mm, and reduced by 20% at the point of maximum hot spot stress. It also showed that ψ at the saddle point dramatically decreased, which was consistent with the case of prestressing level. 3.3.3 Effect of CFRP configuration Fig. 8(d) shows the effect of CFRP layers and CFRP width on ψ under the same prestressing level. It was found