Evaluation of Plastic Collapse Bending Load of Elbows with Thinning Area of Various Shapes

여러 형상의 감육부를 가진 엘보우의 소성붕괴 굽힘 하중의 평가

  • Shin, Kyu-In (Energy.Safety Research Institute, Chung Ang University) ;
  • Lee, Sung-Ho (Korea Electric Power Research Institute) ;
  • Yoon, Kee-Bong (Department of Mechanical Engineering, Chung Ang University)
  • 신규인 (중앙대학교 차세대에너지.안전연구소) ;
  • 이성호 (한국전력 전력연구원) ;
  • 윤기봉 (중앙대학교 기계공학부)
  • Published : 2008.06.30

Abstract

Elbows with various shapes of local wall thinning were numerically analyzed by finite element method to get load-displacement curves and the maximum loads. Results were compared with the experimental data obtained by another study. Elastic-plastic analysis were carried out under the combined loading conditions of internal pressure and in-plane bending loads. Two types of bending loads were considered such as elbow opening mode and elbow closing mode. Also, two different wall thinning geometries were modeled. Wall thinning area located extrados or intrados of elbow inner surface was considered. Longitudinal and circumferential lengths of the thinning area and the thinned thickness were varied for analysis. The results showed that the maximum load of the wall-thinned elbow decreased with increasing of the circumferential thinning length and the thinned thickness in both of extrados and intrados thinning locations in both loading types. The maximum load obtained by the analysis were in good agreement with the experimentally measured maximum load with the same wall thinning type and dimensions. This supports accuracy of the analysis results obtained in this study.

Keywords

References

  1. 이성호, 박치용, 이정근, 김범년, 김태룡, 외 11명, '감육배관 관리기술 최적화 및 적용 연구', 한전전력연구원 보고서, A04NT02, 2006
  2. R. J. Jospin, 'Displacement Estimates of Pipe Elbows Prior to Plastic Collapse Loads', Nuclear Engineering and Design, Vol. 178, pp. 165-178, 1997 https://doi.org/10.1016/S0029-5493(97)00220-3
  3. T. Ying, and M. Vernon, 'Correlation of In-Plane Bending Test and FEA Results for Thin-walled Elbows,' Nuclear Engineering and Design, Vol. 217, pp. 21-39, 2002 https://doi.org/10.1016/S0029-5493(02)00137-1
  4. T. L. Gerber, P. C. Riccardella, A. Y. Kuo, and D. R. Pitcairn, 'Acceptance Criteria for Structural Evaluation of Erosion-Corrosion Thinning in Carbon Steel Piping', EPRI NP-5911SP, 1988
  5. L. Zhang, Y, Wang and C. Liu , 'Evaluation of Local Thinned Pressurized Elbows', International Journal of Pressure Vessels and Piping, Vol. 78, pp. 697-703, 2001 https://doi.org/10.1016/S0308-0161(01)00125-9
  6. A. Robertson, H. Li and D. Mackenzie, 'Plastic Collapse of Pipe Bends under Combined Internal Pressure and In-plane Bending', International Journal of Pressure Vessels and Piping, Vol. 82, pp. 407-416, 2005 https://doi.org/10.1016/j.ijpvp.2004.09.005
  7. A. S. Mohab and Y. A. Y. Maher, 'Nonlinear Analysis and Plastic Deformation of Pipe Elbows Subjected to In-Plane Bending', International Journal of Pressure Vessels and Piping, Vol. 75, pp. 603-611, 1998 https://doi.org/10.1016/S0308-0161(98)00059-3
  8. 심상훈, 송정수, 윤기봉, 황경모, 진태은, 이성호, 'CANDU형 원전 2차 배관의 침부식 감육관리 방 법에 관한 연구', 한국에너지공학회지, Vol. 11, No. 1, pp. 18-25, 2002