Prediction of non propagating cracks

Haddad, Madhar; Topper, T. H.; Smith, K. N.

doi:10.1016/0013-7944(79)90081-x

Cited by 922 publications

(416 citation statements)

References 7 publications

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“…Some studies have attempted to address this need, including the work of Marrey et al [6] in which an El-Haddad type approach [7], accounting for crack sizes which are below a microstructural threshold, was applied to fracture mechanics calculations for a CoCr alloy stent, facilitating prediction of the minimum size of an initial flaw in a stent strut which could cause failure. A key conclusion of this work was the need for microstructural modelling in stent fatigue assessment.…”

Section: Introductionmentioning

confidence: 99%

Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material

Sweeney

O’Brien

Dunne

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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This paper presents a framework of experimental testing and crystal plasticity micromechanics for high cycle fatigue (HCF) of micro-scale L605 CoCr stent material.Micro-scale specimens, representative of stent struts, are manufactured via laser micromachining and electro-polishing from biomedical grade CoCr alloy foil. Crystal plasticity models of the micro-specimens are developed using a length scale-dependent, strain-gradient constitutive model and a phenomenological (power-law) constitutive model, calibrated from monotonic and cyclic plasticity test data. Experimental microstructural characterization of the grain morphology and precipitate distributions is used as input for the polycrystalline finite element (FE) morphologies. Two microstructure-sensitive fatigue indicator parameters are applied, using local and non-local (grain-averaged) implementations, for the phenomenological and length scale-dependent models, respectively, to predict fatigue crack initiation (FCI) in the HCF experiments.

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Section: Introductionmentioning

confidence: 99%

Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material

Sweeney

O’Brien

Dunne

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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“…Comparison of the predictive models by Murakami and Endo [3] and El Haddad et al [4] were made. Whereas the √ area model is well applicable to failure resulting from inclusions in smooth specimens, the El Haddad et al approach shows a higher accuracy for pre-pitted specimens.…”

Section: Discussionmentioning

confidence: 99%

“…(2) according to El Haddad et al [4]. Half of the pit width on the surface was used as the defect size l and the geometry factor was empirically determined (Y = 0.65) as discussed in [1].…”

Section: Matec Web Of Conferencesmentioning

confidence: 99%

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Fatigue assessment of corroded turbine blade steels

Schönbauer¹,

Perlega²,

Karr³

et al. 2014

MATEC Web of Conferences

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“…The threshold stress for a crack centred in an infinitely wide plate subject to mode I loading can be described by means the El Haddad-Smith-Topper equation [4]:…”

Section: Introductionmentioning

confidence: 99%

A unifying approach to fatigue design in presence of defects and notches subject to uniaxial loading

Atzori

Lazzarin

Meneghetti

2014

MATEC Web of Conferences

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Abstract. In the recent past, Atzori and Lazzarin proposed a diagram able to include the geometrical effects on the fatigue limit of defects, short cracks, long cracks and U-shaped notches of whatever severity. The diagram shows that defect sensitivity and notch sensitivity can be considered as two sides of the same medal, thus creating a bridging between Linear Elastic Fracture Mechanics and Notch Mechanics. The fundamental material parameter, dependent on the load ratio, necessary to define the diagram is the El Haddad-Smith-Topper length parameter a 0 defined by the plain material fatigue limit and the threshold value of the mode I stress intensity factor for long cracks. It is worth noting that a 0 does not contain any geometry-related parameter. The diagram has been validated in the past against a number of experimental results and has been subsequently extended to sharp and blunt V-shaped notches, dependent on their absolute dimensions. After summarising the theory supporting the approach, some application examples relevant to both defect and notch sensitivity will be given.

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Prediction of non propagating cracks

Cited by 922 publications

References 7 publications

Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material

Micro-scale testing and micromechanical modelling for high cycle fatigue of CoCr stent material

Fatigue assessment of corroded turbine blade steels

A unifying approach to fatigue design in presence of defects and notches subject to uniaxial loading

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