A finite element analysis of three point bend crack path constraint specimens
- University College, London (United Kingdom)
The complete solution of a fatigue crack growth problem includes determination of the crack path. It is well known that in an isotropic material under essentially elastic conditions fatigue cracks tend to grow in Mode I. In general Mode I crack surfaces and crack fronts are curved, and are difficult to predict. In practice crack paths in structures, and associated crack growth rate data, are usually determined by large scale structural tests. Geometric constraints sometimes confine a crack to a particular path, and this may lead to mixed mode fatigue crack growth behavior. For example, in tubular welded joints crack growth is usually confined to the toe of a weld. Better understanding is needed of the extent to which welds and other notches constrain crack growth to particular paths, and of the circumstances under which this leads to mixed mode fatigue crack growth. A family of three point bend mixed Modes I and II specimens has been designed for tests to investigate crack path constraint. Side grooved versions of the specimens are used to constrain the crack path. The paper presents some stress intensity factors for these specimens obtained using three dimensional finite element analysis. In the two dimensional case, if K{sub I} and K{sub II} are normalized in terms of the shear force and bending moment on the crack plane, then the normalized values are independent of crack offset for a wide range of offsets. For two types of side groove three dimensional analysis shows that the K{sub I}/K{sub II} ratio at both the specimen centre and the groove root falls within a narrow scatter band over a wide range of crack depths.
- OSTI ID:
- 205410
- Report Number(s):
- CONF-950695-; ISBN 0-7918-1309-6; TRN: IM9615%%190
- Resource Relation:
- Conference: International conference on offshore mechanics and arctic engineering, Copenhagen (Denmark), 18-22 Jun 1995; Other Information: PBD: 1995; Related Information: Is Part Of OMAE 1995 -- Proceedings of the 14. international conference on offshore mechanics and arctic engineering. Volume 3: Materials engineering; Salama, M.M. [ed.] [Conoco, Inc., Ponca City, OK (United States)]; Toyoda, Masao [ed.] [Osaka Univ., Suita, Osaka (Japan)]; Liu, S. [ed.] [Colorado School of Mines, Golden, CO (United States)]; Santos, J.F. dos; Kocak, M. [eds.] [GKSS, Geesthacht (Germany)]; Patterson, E.A. [ed.] [Univ. of Sheffield (United Kingdom)]; Berge, S. [ed.] [Univ. of Trondheim (Norway)]; Stacey, A. [ed.] [Health and Safety Executive, London (United Kingdom). Offshore Safety Div.]; PB: 600 p.
- Country of Publication:
- United States
- Language:
- English
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