Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
Residual Strength and Fatigue Lifetime of ... - Solid Mechanics Residual Strength and Fatigue Lifetime of ... - Solid Mechanics
listed in Table 4.1. The length and width of the beam are 215 mm and 65 mm respectively. The beam contains an initial 10 mm long face/core crack. 8-node isoparametric elements (PLANE82) are used in the finite element model. The finite element model of the beam is shown in Figure 4.3. The strain energy release rate and mode-mixity are calculated from the finite element analysis at the end of each cycle. Utilising the relationships between crack growth rate and strain energy release rate for a range of mode-mixities as inputs to the FE routine, the crack increment for each cycle is determined and the finite element model with a new crack length is updated. A remeshing algorithm is employed to simulate the crack growth. Due to the current lack of suitable experimental fatigue crack growth rate data, the crack growth rate vs. strain energy release rate is for simplicity assumed to be constant for mode-mixity phase angles larger and smaller than -10 and chosen arbitrarily as da dN da dN 0 . 001G for k>-10 (4.9) 0 . 0008G for k
Figure 4.3: Finite element model of the sandwich beam. The smallest element size is 3.33 m. Figure 4.4: Route diagram of the developed fatigue crack growth scheme. 69 x y
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listed in Table 4.1. The length <strong>and</strong> width <strong>of</strong> the beam are 215 mm <strong>and</strong> 65 mm respectively. The<br />
beam contains an initial 10 mm long face/core crack. 8-node isoparametric elements (PLANE82)<br />
are used in the finite element model. The finite element model <strong>of</strong> the beam is shown in Figure<br />
4.3. The strain energy release rate <strong>and</strong> mode-mixity are calculated from the finite element<br />
analysis at the end <strong>of</strong> each cycle. Utilising the relationships between crack growth rate <strong>and</strong> strain<br />
energy release rate for a range <strong>of</strong> mode-mixities as inputs to the FE routine, the crack increment<br />
for each cycle is determined <strong>and</strong> the finite element model with a new crack length is updated. A<br />
remeshing algorithm is employed to simulate the crack growth. Due to the current lack <strong>of</strong><br />
suitable experimental fatigue crack growth rate data, the crack growth rate vs. strain energy<br />
release rate is for simplicity assumed to be constant for mode-mixity phase angles larger <strong>and</strong><br />
smaller than -10 <strong>and</strong> chosen arbitrarily as<br />
da<br />
dN<br />
da<br />
dN<br />
0 . 001G<br />
for k>-10 (4.9)<br />
0 . 0008G<br />
for k
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