PSI - Issue 46

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Alok Gupta et al. / Procedia Structural Integrity 46 (2023) 35–41 Alok Gupta et al. / Structural Integrity Procedia 00 (2021) 000–000

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Failure Points

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3.2. Fracture surface The SEM micrographs of fracture surface of the first failure locations in the bracket are shown in Fig. 5. The fracture surface is split into two zones: (1) zone of crack initiation and crack propagation, and (2) zone of fast fracture forming the lip as indicated in Fig. 5(a). From Fig. 5(b), the initiation location is marked as Lack of Fusion (LOF) void and the beach marks, indicating cyclic crack propagation, can also be clearly seen. The LOF voids are evident both at the surface (see Fig. 5(b) and Fig. 5(c)) and also internal into the bulk material (see Fig. 5(a)). Fig. 4. Bracket LCF test (BT2) results: (a) first crack in top of the right main strut, (b) cyclic loops at first failure point, (c) second crack in top of the left main strut, (d) cyclic loops at second failure point, and (e) the load history of max, mean and min forces.