負の応力比における疲労亀裂進展時の亀裂開閉口挙動の評価

抄録

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