Variations of a Global Constraint Factor in Cracked Bodies Under Tension and Bending Loads

Newman, J. C.; Crews, John H.; Bigelow, C. A.; Dawicke, D. S.

doi:10.1520/stp14629s

Cited by 45 publications

(36 citation statements)

References 18 publications

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“…Studies in [56] and [57] have revealed that, for a given thickness, the CTOA was independent of specimen and loading types and specimen in-plane dimensions for cases where the crack lengths and un-cracked ligament lengths were at least four times greater than the specimen thickness. Interestingly this is the same limit value of ligament slenderness that was found for the δ 5 R-curve to be independent on the specimen's in-plane dimensions.…”

Section: Figure 11mentioning

confidence: 99%

Fracture and damage mechanics modelling of thin-walled structures – An overview

Zerbst¹,

Heinimann

Donne³

et al. 2009

Engineering Fracture Mechanics

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Section: Figure 11mentioning

confidence: 99%

Fracture and damage mechanics modelling of thin-walled structures – An overview

Zerbst¹,

Heinimann

Donne³

et al. 2009

Engineering Fracture Mechanics

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“…The stationary crack results in Ref. 94 Two recently obtained sets of two and three-dimensional largestrain, elastic-plastic finite-element analysis results for compact (CT) and other specimen geometries shed considerable light on the details of three-dimensional constraint effects, especially when the two s e t s of results are considered together. Figure 12 shows two and threedimensional analysis results obtained by Brocks and presented by Somer and Aurich 1961, for double-edge-cracked tensile, center-cracked-tensile and compact specimens.…”

Section: Additional Axisymmetric and Tbree-dimensional Constraint Auamentioning

confidence: 99%

Patterns and Perspectives in Applied Fracture Mechanics

Merkle

1995

Fracture Mechanics: 26th Volume

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This fifth Jerry L. Swedlow Memorial Lecture begins with a brief philosophical and historical overview of applied fracture mechanics, particularly as it pertains to the safety of pressure vessels. It then progresses to a more-or-less chronological panorama of experimental and analytical results pertaining to the important subject of constraint, a fundamental aspect of fracture mechanics in which Jerry Swedlow had a keen interest and to which he made valuable contributions. To be truly useful and dependable in application to the safety analysis of real structures, new analysis developments must be physically realistic. That means that they must accurately describe physical cause and effect. Consequently, before useful mathematical modeling can begin, a pattern of cause and effect must be established from experimental data. This can be a difficult and time consuming process, but it is worth the effort. Accordingly, a central theme of this paper is that, consistent with the scientific method, the search for patterns is constant and vital. This theme is well illustrated historically by the development of small, single-specimen, fracture toughness testing techniques. It is also illustrated, at the end of the present paper, by the development, based on two different published large-strain, elasticplastic, three-dimensional finite-element analyses, of a hypothesis concerning three-dimensional loss of constraint. Specifically, it appears that, at least in standard compactspecimens, when a generalization of Irwin's thickness-normalized plastic-zone parameter, p, reaches a value close to 2n, the through-thickness contraction strain at the apex of the near-tip logarithmic-spiral slip-line region becomes the dominant negative strain accommodating crack opening. Because slip lines passing from the midplane to the stress-free side surfaces do not have to curve, once these slip lines are established, stresses near the crack tip are only elevated by strain hardening and constraint becomes significantly relaxed. This hypothesis, based on published threedimensional elastic-plastic analyses, provides a potentially valuable means for gaining additional insight into constraint effects on fracture toughness by considering the roles played by the plastic strains as well as the stresses that develop near a crack tip.

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“…This is primarily due to significant difference between the stressstate at the tip of a through-thickness crack in a plate of arbitrary thickness and that corresponding to either the idealized plane-stress or plane-strain conditions. In the case of fatigue crack growth, this difference often manifests itself in a transition from flat to slant crack growth in thin structures [3]. For fatigue life calculations, this difference in the in-plane and out-of-plane constraints may significantly affect the accuracy of predictions [2] when the base-line fatigue crack growth curves generated using standard specimens (often under plane-strain conditions) are applied to predict the fatigue life of engineering structures of thin cross section.…”

Section: Introductionmentioning

confidence: 99%

“…Accurate assessment of the thickness effect on fatigue crack growth rates and fracture toughness has relied on computational methods, such as the finite element method, where the results are to some extent dependent on the mesh density of the finite element model. Newman and his colleagues [3,12] conducted detailed full three-dimensional finite element analyses for through-thickness cracks in an elastic-perfectly plastic material. From these results an approximate equation [12] for the constraint factor has been constructed, which varies with the ratio of crack-tip plastic zone to plate thickness [2,3] in the case of small-scale yielding.…”

Section: Introductionmentioning

confidence: 99%

“…Newman and his colleagues [3,12] conducted detailed full three-dimensional finite element analyses for through-thickness cracks in an elastic-perfectly plastic material. From these results an approximate equation [12] for the constraint factor has been constructed, which varies with the ratio of crack-tip plastic zone to plate thickness [2,3] in the case of small-scale yielding. In the presence of large-scale yielding, no results are currently available on the appropriate value of the constraint factor.…”

Section: Introductionmentioning

confidence: 99%

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