PSI - Issue 75

Xiru Wang et al. / Procedia Structural Integrity 75 (2025) 85–93 Wang / Structural Integrity Procedia 00 (2025) 000 – 000

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Fig. 2. (a) Reverse engineering approach, (b) Mesh study on 2D-FE models, (c) Mesh of 3D-FE model

4. Fatigue life analysis 4.1. Critical distance approach

As shown in section 2, fatigue life and local weld quality seem to have a weak correlation in this investigated case. This may lead to the conclusion that local stress concentrations at the surface are not strongly related to the fatigue life of the specimens. For this reason, the critical distance theory (CDT) is used in this work to cover this surface effects. The CDT refer to (Peterson, 1959), where the stress at a material-dependent critical distance from the most heavily loaded point can be used directly to estimate fatigue strength. Later, Tanaka (Tanaka, 1983) and Taylor (Taylor, 1999) demonstrated that the same critical distance approach based on linear-elastic fracture mechanics can be used to determine the fatigue strength of metallic, notched components. The material-dependent critical distance for cyclic loading is defined as follows: = 1 ( ∆ ℎ ∆ 0 ) 2 (1) Where ∆ ℎ is the range of the cyclic stress intensity factor and ∆ 0 is the amplitude of the so-called endurance limit of the material. A comparatively simpler approximation of the critical distance in mm depending on the tensile strength of the material in MPa was already suggested by (Lawrence et al. , 1978; Lawrence, Ho and Mazumdar, 1981):