Crack closure behavior at fatigue crack growth under negative stress ratio

Yamaguchi, Yoshihito; Hasegawa, Kunio; Li, Y.

no journal, , 

Influence of magnitude of load amplitude and stress ratio on crack closure behavior for the fatigue crack growth was experimentally investigated by fatigue tests in air environment. Cyclic loads were applied to a specimens and magnitude of load amplitude was stepwise increased under constant load ratio. It was confirmed that an effective load amplitude on fatigue crack growth increases with increasing load amplitude. Then, the effective load amplitude becomes constant value if magnitude of load amplitude is larger than threshold. In addition, the effective load amplitude decreases with decreasing the load ratio. Applicability of fatigue crack growth evaluation method in code and standard for fatigue crack growth under negative stress ratio is discussed on the basis of the experimental results.