PSI - Issue 13

Shigeru Hamada et al. / Procedia Structural Integrity 13 (2018) 1026–1031 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

1031

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to a round bar jig that is cyclically twisted enables pure Mode II loading on the specimen, and direct successive observation is also possible. Figure 7 shows a part of the test results on stainless steel subjected to cold rolling as a preliminary test. From Fig. 7, it is understood that cracks are not continuous, and the crack propagates on a unit; this is DAFCP.

Adhered thin film with precrack

precrack

Round bar with cyclic torsion load

Fig. 6. Proposed novel fatigue crack propagation test method under Mode II loading.

10 μ m

(a)

(c)

(b)

(c)

2 μ m

Fig. 7. Fatigue crack morphology after pure cyclic Mode II loading (a) optical micrograph, (b) SEM image, (c) Detail of crack tip (Hamada et al. 2018).

5. Conclusion

We re-examined the Mode II fatigue crack propagation mechanism for fatigue crack propagation in RCF, by focusing on the location where the phenomena occur, and not on conventional loading forms such as Modes I and II. We developed a novel test method based and thus elucidated the Mode II fatigue crack propagation mechanism.

References

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