PSI - Issue 21

28 8

Author name / StructuralIntegrity Procedia 00 (2019) 000 – 00

Emre Kurt et al. / Procedia Structural Integrity 21 (2019) 21–30

0.00 2.00 4.00

-6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00

crack-2

crack-1

0

0.2

0.4

0.6

0.8

1

-10.00 -8.00 -6.00 -4.00 -2.00

K II (MPa·m½)

0 K II (MPa·m½)

0.2

0.4

0.6

0.8

1

Nondimensional position, s

Nondimensional position, s

(b)

-8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00

0.00 2.00 4.00

crack-2

crack-1

-10.00 -8.00 -6.00 -4.00 -2.00

K III (MPa·m½)

K III (MPa·m½)

0

0.2

0.4

0.6

0.8

1

0

0.2

0.4

0.6

0.8

1

Nondimensional position, s

Nondimensional position, s

(c) Fig. 9. Distributions of mixed mode SIFs, a) K I , b) K II , c) K III , along the crack fronts from each propagation step for both cracks. Solid model for final crack propagation step (23 rd crack front) and fatigue crack growth surfaces predicted by FCPAS using the developed 3-D criteria (Eqs. 2-4) are given from different views in Fig. 10.

B-B view

A-A view

B-B view

A-A view

Fig. 10. Solid model and fatigue crack growth surfaces for final crack propagation step (23 rd crack front).

Using the incremental crack growth lives for each propagation step, the crack lengths for both cracks as a function of accumulated load cycles are plotted in Fig. 11. The numerical and experimental crack growth data of Shu et al. (2017) are also given in the figure for comparison. It can be clearly seen from the figure that the crack growth rates predicted by FCPAS for both cracks using the developed 3-D criteria are in excellent agreement with the experimental data.