B-45 局部減肉を有する炭素鋼配管の破壊挙動

概要

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To evaluate the structural integrity of power plant piping, monotonic bending tests and low cycle fatigue tests were conducted on 100mm diameter (100A) full-scale carbon steel pipe specimens with local wall thinning. The local wall thinning was simulated as an eroded part. From the monotonic bending tests in case that eroded area was subjected tensile stress, the fracture behavior at maximum moments was classified into two types, ovalization and crack initiation. To evaluate the difference of fracture behavior, the finite element analyses were conducted. Using the Mises strain at the maximum eroded area and multiaxial fracture strain estimated by modified Weiss's method, the difference of fracture behavior could be explained. From the low cycle fatigue tests, the fatigue strength of eroded pipes with 100mm in eroded axial length, 0.5 in normalized eroded depth and 90 deg. in eroded angle is almost equal to the design fatigue curve in ASME B&PV Code Sec. III. To evaluate the local strain amplitude in the cyclic bending tests, finite element analyses were conducted. Using Mises strain amplitude and low cycle fatigue curve, the number of cycles to 25% moment decreasing of eroded pipes were evaluated, conservatively.
社団法人日本機械学会の論文
2000-03-29