PSI - Issue 39

Wei Song et al. / Procedia Structural Integrity 39 (2022) 214–221 Author name / Structural Integrity Procedia 00 (2020) 000–000

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Fig. 2 (a) Schematic geometry of axial misalignment specimen; (b) Schematic geometry of angular misalignment specimen; (c) 2D FEM model dimensions and mesh details of SED models and ENS models.

3. Experimental results 3.1. Fatigue initiation points in LCWJ

Fig. 3 shows the SED values at weld toe and weld root in LCWJs considering axial and angular misalignments. In the Fig. 3(a)-(b), the values of SED for p1 are always the maximum with the increases of axial misalignment, which means that the fatigue crack around this point expected to unstable propagation, the SED values of p2 and p3 decrease since the compressive secondary bending stress caused by axial misalignment occurs around the notches. As shown in Fig.3(c)-(d), the crack propagation tendency decreases at p2 and p4 because of the values of SED trend to reduce under the influence of angular misalignments, p1 also the risky point under angular misalignments. Comprehensively, the weld toe and weld root at p1 is the most potential failure point when local stress reached critical fatigue strength. Thus, the potential fatigue initiation points in LCWJs could be estimated by the SED results considering the misalignment effect. Fig. 4 show the results of SED for different weld penetration lengths and different types of misalignments, corresponding SED values increase constantly, while the p/t decrease or the misalignments at increasing rate. Compared with the SED values of weld toe (Fig. 4(a)-(c)) and weld root (Fig. 4(b)-(d)), it shows that the effect of weld penetration length ratio (p/t) at weld root is more significant than that weld toe, and the weld toe is more sensitive for the effect misalignment, no matter which is axial misalignments or angular misalignments. For the same model, the SED values at weld toe were increased with the increases of misalignment degree, which implies that the fatigue failure point tends to the weld toe.