Brittle fracture from interacting surface breaking defects

Bezensek, B. and Hancock, J.W. (2001) Brittle fracture from interacting surface breaking defects. In: Proceedings of the International Conference ASME Pressure Vessels and Piping, Atlanta, Georgia, U.S.A, 22-26 July 2001, pp. 25-32.

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Abstract

Pressure Vessel codes, such as ASME Section XI [8], define characterisationprocedures for complex defects. The present work examines these approaches by studying the interaction of two coplanar surface breaking defects numerically andexperimentally. In the numerical study, the line-spring concept of Rice and Levy [12] was used to model a series of evolving crack profiles which develop in fatigue from two adjacent semi-elliptical starter notches. The defects coalesced in fatigue to form asingle complex defect which initially has a marked re-entrant sector. Enhanced stressintensity factors were determined in the re-entrant sector of the coalesced defects and these were confirmed by experimental observations of rapid fatigue crack growth. The enhanced stress intensity factors were associated with a loss of crack tip constraint asparameterised by T [11]. Experiments designed to measure the lower shelf toughness of defect configurations with re-entrant sectors were performed on a plain Carbon-Manganese steel. Three representative geometries with re-entrant sectors were considered. The low fracture resistance of profiles with pronounced re-entrant sectors leads to non-conservatism in the codified recharacterisation procedures of complex defects failing on the lower shelf.

Item Type:Conference Proceedings
Additional Information:Held as a joint symposium at the 2001 ASME pressure vessels and piping conference
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Bezensek, Dr Bostjan and Hancock, Professor John
Authors: Bezensek, B., and Hancock, J.W.
Subjects:T Technology > TA Engineering (General). Civil engineering (General)
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
ISSN:0-7918-1678-8

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