抄録
There is a possibility that the crack growth rate of stress corrosion cracking and fatigue crack depend on the value of ∂K/∂a (differential term of stress intensity factor) as well as stress intensity factor K. In this study, the effect of ∂K/∂a on crack growth rate was investigated during the fatigue test. Two types of specimens were prepared. One is CT specimen of which K increases under constant loading. The other is CDCB specimen of which K is constant. The effect of ∂K/∂a was clarified by comparing the CT specimen and CDCB specimen under same stress intensity factor. In addition, ΔK corrections considering ∂K/∂a were conducted for CT specimens. As a result, the crack growth rates in CT specimens were larger than CDCB specimens in the same ΔK. Corrected ΔK considering ∂K/∂a is mostly coincides with the value of the CDCB specimen. From those results, the crack growth rate varied due to the effect of ∂K/∂a in fatigue crack propagation was experimentally clarified. In addition, elimination of the influence of ∂K/∂a is possible by ΔK correction.
