PSI - Issue 57

Mehdi Ghanadi et al. / Procedia Structural Integrity 57 (2024) 386–394 Mehdi Ghanadi et al./ Structural Integrity Procedia 00 (2023) 000 – 000

390

5

Figure 2. First principal stress distribution of models (a) 1 2 3 t t mm = = , (b) through the normalized thickness The cumulative highly stressed area of the joint is depicted in Fig. 3. The graph shows that as plates become thicker, the stress magnitude becomes larger, while the relative regions containing high-stress values are becoming smaller.

Figure 3. Stress variation across the surface area

The probabilistic surface stress ( equ   ) is then calculated based on Eq.(2) , and its standard deviation is plotted against different values of the Weibull shape parameter,  , Fig. 4. The plot reveals that small values  lead to higher standard deviation, however, as  becomes larger, variation declines considerably until it reaches to its minimum value for 12  = , which can be considered as fitted Weibull shape parameter for this case since the standard deviation of surface probabilistic stress reached a platea u for larger  .

Figure 4.Variation of standard deviation with respect to β

The logarithmic Basquin equation, Eq.(3), which represents the relation between stress range and the numberof cycles to failure in a finite regime, is used to find the slope m and standard deviation of scatter data (Hobbacher, 2016).