Transactions of the Korean Society of Mechanical Engineers (대한기계학회논문집)

The Korean Society of Mechanical Engineers (대한기계학회)
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A Study on Fatigue Crack Growth Characterization Of Surface Crack In Pressure Vessel Materials

압력용기 소재에서의 표면균열의 피로균열 성장특성에 관한 연구

  • 허용학 (한국표준연구소, 재료응용연구실) ;
  • 이주진 (한국표준연구소 재료응용연구실) ;
  • 한지원 (한국표준연구소 재료응용연구실) ;
  • 김종집 (한국표준연구소 재료응용연구실) ;
  • 문한규 (한국표준연구소 재료응용연구실)
  • Published : 1990.04.01
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Abstract

Cracks found in pressure vessels have been reported to be mostly semi-elliptic surface cracks. The fatigue crack growth behaviour of the surface cracks on pressure vessel materials, SPV 50Q and API 5A-K55, was studied with the consideration of the crack opening character. To determine the crack opening loads for the surface cracks, the displacement/strain were measured at three positions; the center and the side of the surface crack, the back face of the specimen using CMOD gauge and strain gauges. The experimental results showed that the crack opening load levels measured at the side of the surface crack were generally a little higher than those measured at the back face. As for the crack growth rates at the different parts of the surface crack, the experiments also showed that, if .DELTA.K$_{eff}$ is used, the exponent n of the Paris' law obtained were the same for the rear and the side parts of the surface cracks.

본 연구에서는 압력용기 소재인 SPV 50Q와 고압강관 소재로 사용하는 SPV 50Q 와 고압강간 소재로 사용하는 API 5A-K55에서의 표면균열의 표면방향과 깊이방향 또한 두께 평균에 대한 균열열림을 스트레인 게이지와 CMOD(Crack Mouth Opening Displace- ment)게이지를 이용하여 측정 비교하였다. 또한 표면균열의 균열 열림하중을 측정위 치에 따라 평가하고, 본연구에 사용한 두 소재에 대해 균열 열림을 고려한 표면균열 진전평가가 각 방향에 대해 이루어졌다.

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