J101014 エルボ配管の低サイクル疲労挙動に及ぼす局部減肉の影響([J10101]原子力施設の耐震安全性に関する実験的・解析的検討(1))

概要

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Low cycle fatigue tests were conducted using 100A elbow pipe specimens of STPT410 with or without local wall thinning. Local wall thinning was machined on the inside of the extrados, crown and intrados in the test elbows to simulate metal loss due to flow-accelerated corrosion or liquid droplet impingement erosion. Low cycle fatigue test were carried out under displacement control with an inner pressure of 9 MPa. The effects of eroded conditions, such as eroded ratio, eroded angle and position, on the low cycle fatigue behavior and fatigue life were discussed. Fatigue lives of these tests are all beneath the fatigue curve based on Manson's common slope method. However, all data were conservative with respect to the ASME design fatigue curve. Therefore, the present elbow specimens had a sufficient safety margin when the fatigue life was estimated from the ASME design fatigue curve. In addition, three-dimensional elastic-plastic analyses were carried out using the finite element method. The crack penetration area and the crack growth direction were successfully predicted by the analyses.
2011-09-11