PSI - Issue 41

Slobodanka Boljanović et al. / Procedia Structural Integrity 41 (2022) 704 – 711 Slobodanka Boljanović et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4. Fatigue strength analysis ( R = 0): (a) a vs. N and (b) b vs. N . Calculated curves generated within the present research.

4.2. Quarter-elliptical crack growth analysis Now the fatigue degradation of a damaged plate (Fig. 1b) is explored through the crack path evaluations in the case of applied maximum force equal to P max = 56000 N ( R = 0.25). Initial elliptical corner flaw is characterized by the following sizes: a 0 = 1.3 mm, b 0 = 1.7 mm in depth and surface direction, respectively. The plate-type configuration, whose width and thickness are equal to w = 70 mm, t = 8 mm, is made of 2024T3 aluminium alloy. Since the surface-flaw phenomenon is one of the key safety-critical issues for moving systems, the durability analysis was performed via the stress intensity factor and crack growth path, using Eq. (3)-(10) with Eq. (1). Fatigue-induced driving forces in the vicinity of crack tip herein examined via the crack growth paths are shown in Fig. 5 for nine different crack growth lengths in depth direction, adopting that the horizontal and vertical axis coincide with the front face and the left side of the plate, respectively.

Fig. 5. Crack growth path evaluations: (a) 1 – a = 2.0 mm, 2 – a = 2.4 mm , 3 – a = 3.4 mm, 4 – a = 4.2 mm; (b) 1 – a = 4.7 mm, 2 – a = 5.4 mm, 3 – a = 6.5 mm, 4 – a = 7.1 mm, 5 – a = 7.3 mm, calculated curves generated within the present research.