Browse > Article
http://dx.doi.org/10.3795/KSME-A.2006.30.8.931

Effect of Structural Geometry and Crack Location on Crack Driving Forces for Cracks in Welds  

Oh Chang-Kyun (고려대학교 기계공학과)
Kim Jong-Sung (한국전력기술(주) 재료기술연구그룹)
Jin Tae-Eun (한국전력기술(주) 재료기술연구그룹)
Kim Yun-Jae (고려대학교 기계공학과)
Publication Information
Transactions of the Korean Society of Mechanical Engineers A / v.30, no.8, 2006 , pp. 931-940 More about this Journal
Abstract
Defect assessment of a weld zone is important in fitness-for-service evaluation of plant components. Typically a J and $C^*$ estimation method for a defective homogeneous component is extended to a mismatched component, by incorporating the effect due to the strength mismatch between the weld metal and the base material. The key element is a mismatch limit load. For instance, the R6/R5 procedure employs an equivalent material concept, defined by a mismatch limit load. A premise is that if a proper mismatch limit load solution is available, the same concept can be used for any defect location (either a weld centre defect or a heat affected zone (HAZ) defect) and for any material combination (either two-material or multi-material combinations; either similar or dissimilar joints). However, validation is still limited, and thus a more systematic investigation is needed to generalise the suggestion to any geometry, any defect location and any material combination. This paper describes the effect of structural geometry on the $C^*$ integral for defective similar welds, based on systematic elastic-creep 2-D and 3-D finite element (FE) analyses, to attempt to elucidate the questions given above. It is found that the existing 'equivalent material' concept is valid only for limited cases, although it provides conservative estimates of $C^*$ for most of cases. A modification to the existing equivalent material concept is suggested to improve accuracy.
Keywords
$C^*$-Integral; Weldment; Equivalent Material; Mismatch Limit Load; Geometry Effect;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Kim, Y. J. and Schwalbe, K. H., 2001, 'Mis-Match Effect on Plastic Yield Loads in Idealised Weldments: Part I-Weld Centre Cracks,' Engineering Fracture Mechanks, Vol. 68,pp. 163-182   DOI   ScienceOn
2 Zahoor, A., 1991, Ductile Fracture Handbook, Vol. 2 Chapter 6 Axial through-wall crack, Novetech Corp
3 Kim, Y. J. and Schwalbe, K. H., 2001, 'Mis-Match Effect on Plastic Yield Loads in Idealised Weldments: Part II-HAZ Cracks,' Engineering Fracture Mechanics Vol. 68, pp. 183-199   DOI   ScienceOn
4 Webster, G.A., and Ainsworth, R. A., 1994, High Temperature Component Life Assessment, Chapman & Hall, London
5 Kim, Y. J., Kocak, M., Ainsworth, R. A. and Zerbst, D., 2000, 'SINTAP Defect Assessment Procedure for Strength Mis-Matched Structures,' Engineering Fracture Mechanics, Vol. 67, pp. 529-546   DOI   ScienceOn
6 Schwalbe, K. H., Zerbst, D., Kim, Y. J., Brocks, W., Comec, A., Heerens, J. and Amstutz, H., 1997, EFAM ETM 97: The ETM Method for Assessing the Significance of Crack-Like Defects in Engineering Structures, GKSS Research Centre, GKSS/98/E/6, Germany
7 Schwalbe, K. H. and Kocak, M., 1997, Mis-Matching of Interfaces and Welds, Proceedings of the 2nd International Conference Mis-Match '96, GKSS Research Centre Publications, Germany
8 Kumar, V., German, M. D. and Shih, C. F., 1981, An Engineering Approach for Elastic-Plastic Fracture, EPRI Report NP 1931
9 British Energy Generation Ltd., 2001, 'R6: Assessment of the Integrity of Structures Containing Defects,' Revision 4
10 Schwalbe, K. H. and Kocak, M., 1994, Mis-Matching of Welds, Proceedings of the International Conference Mis-Match '93, ESIS 17, Mechanical Engineering Publications, London
11 Lei, Y. and Ainsworth, R. A., 1997, 'A J Integral Estimation Method for Cracks in Welds with Mismatched Mechanical Properties,' International Journal of Pressure Vessels and Piping, Vol. 70, pp. 237-245   DOI   ScienceOn
12 Riedel, H., 1987, Fracture at High Temperature, Berlin: Springer-Verlag
13 Kim, Y. J., Schwalbe, K. H. and Ainsworth, R. A., 2001, 'Simplified J Estimation Based on Engineering Treatment Model for Homogeneous and Mis-Matched Structures,' Engineering Fracture Mechanics, Vol. 68, pp.9-27   DOI   ScienceOn
14 Lei, Y., Tao, J. and Li, P. N., 1999, 'Limit Load and J Estimates of a Center Cracked Plate with an Asymmetric Crack in a Mismatched Weld,' International Journal of Pressure Vessels and Piping, Vol. 76, pp. 747-757   DOI   ScienceOn
15 Schwalbe, K. H., Ainsworth, R. A., Eripret, C., Gilles, P., Kocak, M., Pisarski, H. and Wang, Y. Y., 1997, 'Common Views on the Effects of Yield Strength Mis-Match on Testing and Structural Assessment. In: Schwalbe K-H and Kocak M, editors. Mis-Matching of Interfaces and Welds,' GKSS Research Centre Publications, Germany, pp. 99-134
16 Schwalbe, K. H., Kim, Y. J., Hao, S., Comec, A. and Kocak, M., 1996, EFAM ETM-MM 96: The ETM Method for Assessing the Significance of Crack-Like Defects in Joints with Mechanical Heterogeneity (Strength Mis-Match), GKSS Research Centre, GKSS/97/E/9, Germany