Tests and analyses for fully plastic fracture mechanics of plane strain mode I crack growth

Frank A. McClintock, Yun Jae Kim, David M. Parks

Research output: Contribution to journalConference article

6 Citations (Scopus)

Abstract

Under monotonic loading, structures should ideally be ductile enough to provide continued resistance during crack growth. Such fully plastic behavior is of interest in design against collisions, tank car accidents, earthquakes, and ship groundings. For fully plastic crack growth in low strength alloys, existing asymptotic solutions for elastic-plastic growing cracks are not applicable because they reach the fracture strain only in regions small compared to the inhomogeneities of the actual fracture process. For the limiting case of non-hardening fully-plastic plane strain crack growth, in a number of geometries and loadings the near-tip fields are characterized in terms of three parameters: an effective angle 2θs between a pair of slip planes, and the normal stress σs and the increment of displacement δus across the planes. This three-parameter characterization is in contrast to the one- or two-parameter (K or J and T or Q) characterization in linear or non-linear elastic fracture mechanics. These θs, σs, and δus parameters are found from the far-field geometries and loadings through slip line fields or least upper bound analyses based on circular arcs. The resulting crack growth, in terms of the crack tip opening angle (CTOA), is a function of θs, σs, and the material. The geometry of the crack growing between two moving slip planes emanating from its tip reduces this function to the critical fracture shear strain left behind the slip planes, γf, as a function of σs. γf(σs) is found theoretically from a hole initiation and growth model. It is also found from preliminary fully plastic crack growth experiments on unequally grooved specimens with fixed-grip extension or 4-point bending of a 1018 CF steel. At high triaxialities and also after strain aging, cleavage intervened abruptly, even during stable, slow deformation.

Original languageEnglish
Pages (from-to)199-222
Number of pages24
JournalASTM Special Technical Publication
Issue number1256
Publication statusPublished - 1995 Dec 1
Externally publishedYes
EventProceedings of the 1994 26th National Symposium on Fracture Mechanics - Idaho Falls, ID, USA
Duration: 1994 Jun 281994 Jun 30

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Fracture mechanics
Crack propagation
Plastics
Geometry
Tank cars
Cracks
Shear strain
Electric grounding
Crack tips
Earthquakes
Accidents
Ships
Aging of materials
Steel
Experiments

ASJC Scopus subject areas

  • Engineering(all)

Cite this

Tests and analyses for fully plastic fracture mechanics of plane strain mode I crack growth. / McClintock, Frank A.; Kim, Yun Jae; Parks, David M.

In: ASTM Special Technical Publication, No. 1256, 01.12.1995, p. 199-222.

Research output: Contribution to journalConference article

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