Stress Intensity Factors for Cracks at Fastener Holes

Nurse, A. D.; O'BRmN, E. w.; Patterson, E. A.

doi:10.1111/j.1460-2695.1994.tb00810.x

Cited by 20 publications

(12 citation statements)

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“…By contrast, because photoelasticity provides only the elastic strain fields in the birefringent coating, it is mainly used to determine experimentally stress intensity factors for complex loading modes in components where the fields are predominantly linear elastic [24][25][26][27]. Because constraint effects that arise in elastic-plastic materials are then weak, such experimental data agree reasonably well with theoretical plane-stress solutions.…”

Section: Introductionsupporting

confidence: 73%

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

MISEREZ

2004

Engineering Fracture Mechanics

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Crack-tip strain fields in high volume fraction ceramic particle reinforced metal matrix composites are assessed using photoelastic measurements. It is shown that the size of the significant crack-tip plastic zones that form in these materials depends on the type and diameter of the reinforcement and on the matrix material. This plastic zone size correlates well with the macroscopic toughness values assessed through J -integral testing. The composites are thus ''metallic'' in the sense that their toughness is mostly composed of plastic energy dissipation around the crack tip. Plastic deformation also induces marked constraint effects that influence the shape of the surface strain fields. It is shown that finite element analysis must be three-dimensional to describe these strain fields, as two-dimensional plane-stress analysis fails to reproduce the experimental data.

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Section: Introductionsupporting

confidence: 73%

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

MISEREZ

2004

Engineering Fracture Mechanics

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“…For a crack propagating through elastic material, the crack flanks would be expected to open as if they were hinged at the crack tip, although in practice the ‘hinge’ is likely to be in the plastic zone ahead of the visible crack tip where void formation within a process zone previews the formation of the crack 42 . This behaviour is evident in the coupon with the unexpanded hole in which, for all crack lengths, the COD decreases approximately linearly from the edge of the hole to zero at a point between 0.6 mm and 1.2 mm ahead of the visible crack tip; values that lie between the plane stress estimate for plastic zone radius (1.83 to 2.6 mm) and plane strain estimates of the plastic zone radius (0.30 to 0.43 mm) 46,47 . In the coupon with the unexpanded hole, the maximum COD, which occurs at the edge of the hole in the UH coupon increases approximately linearly with crack length from about 0.02 mm at a = 1 mm to about 0.05 mm at a = 3.7 mm.…”

Section: Resultsmentioning

confidence: 83%

Analysis of the effects of cold expansion of holes using thermoelasticity and image correlation

Bäckman

Cowal

Patterson

2010

Fatigue Fract Eng Mat Struct

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A B S T R A C T Although cold expansion has been shown to have a positive effect on fatigue life, little work to date has been performed to evaluate the evolution of the strain field surrounding the crack tip on the mandrel entry and exit faces in cold-expanded coupons. Full-field strain measurements using both digital image correlation (DIC) and thermoelastic stress analysis (TSA) were used to compare the strains during crack growth around holes that had and had not been cold-expanded by 4%. Simple rectangular fatigue coupons were machined from 2024-T3 aluminium sheet, half had simple open, unexpanded holes and half had cold-expanded open holes. A DIC system was used to monitor the (mandrel) entry face of the coupon while a TSA system was used to monitor the (mandrel) exit face of the coupon during cyclic tensile loading (R-ratio = 0.1). These two systems provide the first published measurements of the simultaneous mandrel entry and exit surface strains surrounding a crack initiating from a cold-expanded hole. The cracks originating from the unexpanded hole exhibit a strain field around the crack tip which is characteristic of a mode I fatigue crack while those emanating from the cold-expanded holes show a significantly lower distribution of strains around the crack tip. Crack opening displacements evaluated from the strain data obtained from DIC, are substantially reduced by the residual compressive stresses from cold expansion, while the overall fatigue data show the life improvement achieved at various applied stress levels.

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“…Transmission photoelasticity suffers from the drawback (particularly as far as fatigue cracks are concerned), that the material behaviour in the process zone will differ from that in the main classes of engineering materials. Reflection photoelasticity can, of course, be used to circumvent this, but is more complex experimentally [3]. Other experimental techniques employed have included caustics [4], interferometry [5], and point measurements with strain gauges [6].…”

Section: Introductionmentioning

confidence: 99%

Measurement of fatigue crack deformation on the macro- and micro-scale: Uniform and non-uniform loading

O’Connor

Nowell

Dragnevski

2016

International Journal of Fatigue

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Stress Intensity Factors for Cracks at Fastener Holes

Cited by 20 publications

References 12 publications

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

Analysis of the effects of cold expansion of holes using thermoelasticity and image correlation

Measurement of fatigue crack deformation on the macro- and micro-scale: Uniform and non-uniform loading

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