半円より奥に深い亀裂の応力拡大係数解の比較

抄録

In nuclear power plants, some cracks attributed to stress corrosion cracking (SCC) have been detected in welds made with nickel alloy weld metals. One of the characteristics of these cracks is that crack aspect ratio a/ℓ is greater than 0.5, where a is the crack depth and ℓ is the crack length. When a crack is detected in components of nuclear power plants during in-service inspection, flaw evaluation is conducted according to the requirement of codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants. Here, the stress intensity factor plays an important role for predicting crack growth behavior due to fatigue and/or SCC. Although several solutions of the stress intensity factor are already given in the JSME code, no solutions are available for the cracks with a/ℓ > 0.5. According to the current code, surface cracks with a/ℓ > 0.5 are characterized as semi-circular shape ℓ = 2a. To evaluate these cracks in a rational manner, several solutions have been proposed for cracks with a/ℓ > 0.5. In this paper, comprehensive comparison was made between solutions for cracks a/ℓ > 0.5, and benchmark analysis on SCC crack growth was performed.