On crack closure and the notch size effect in fatigue

McEvily, A.J.; Minakawa, K.

doi:10.1016/0013-7944(87)90049-x

Cited by 57 publications

(29 citation statements)

References 3 publications

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“…The growth of mechanically small cracks from notches is largely affected by plasticityinduced closure [57]. For example, the work of McClung and Sehitoglu [58] on 1026 steel illustrates that the propagation of mechanically short cracks from notches may be effectively treated using plasticity-induced closure concepts, as shown in Figure 31.…”

Section: Notch Effectsmentioning

confidence: 96%

Basic issues in the mechanics of high cycle metal fatigue

McDowell

1996

Int J Fract

159

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Mechanics issues related to the formation and growth of cracks ranging from subgrain dimension to up to the order of one mm are considered under high cycle fatigue (HCF) conditions for metallic materials. Further efforts to improve the accuracy of life estimation in the HCF regime must consider various factors that are not presently addressed by traditional linear elastic fracture mechanics (LEFM) approaches, nor by conventional HCF design tools such as the S-N curve, modified Goodman diagram and fatigue limit. A fundamental consideration is that a threshold level for AK for small/short cracks may be considerably lower than that for long cracks, leading to non-conservative life predictions using the traditional LEFM approach.Extension of damage tolerance concepts to lower length scales and small cracks relies critically on deeper understanding of (a) small crack behavior including interactions with microstructure, (b) heterogeneity and anisotropy of cyclic slip processes associated with the orientation distribution of grains, and (c) development of reliable small crack monitoring techniques. The basic technology is not yet sufficiently advanced in any of these areas to implement damage tolerant design for HCE The lack of consistency of existing crack initiation and fracture mechanics approaches for HCF leads to significant reservations concerning application of existing technology to damage tolerant design of aircraft gas turbine engines, for example. The intent of this paper is to focus on various aspects of the propagation of small cracks which merit further research to enhance the accuracy of HCF life prediction. Predominant concern will rest with polycrystalline metals, and most of the issues pertain to wide classes of alloys.

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Section: Notch Effectsmentioning

confidence: 96%

Basic issues in the mechanics of high cycle metal fatigue

McDowell

1996

Int J Fract

159

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“…Der Einspielvorgang wird nach Vormwald [1523] und anderen Autoren [1214,1216,1217,1563] In ähnlicher Weise sehen Li u. Edwards [1441][1442][1443] die maximale Scherdehnungsschwingbreite (maximal innerhalb des Dehnungstensors) als maßgebend für den Rißfortschritt im Stadium I an. Als ein grund-legendes Phänomen ist festzustellen, daß der Kurzriß sofort vollständig offen bleibt, wenn auf eine größere (Zug-)Dehnungsamplitude eine (wesentlich) kleinere Dehnungsamplitude folgt, selbst wenn letztere fast ganz im Druckdehnungsbereich liegt, Abb.…”

Section: Rißschließen Beim Kurzriß Unter Mehrstufen-und Random-belastungunclassified

Ermüdungsfestigkeit

2007

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“…3). Chapetti rewrite the equation of crack closure effect given by McEvily and Minakawa (1987) based on the term .…”

Section: Closure Effectmentioning

confidence: 99%

New Generalized Fatigue Model: Case of a Semi-elliptical Defect

Noui

Boukharouba

2014

Procedia Materials Science

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A new fatigue crack model is proposed for long cracks, by generalization of Murakami's model established only for short cracks. The new model is based on the calculation of stress intensity factor (SIF), using directly the new areas created during the crack propagation with an efficiency that we consider acceptable. To take into account the behaviour of long cracks during propagation, a correction parameter denoted by was introduced. This parameter takes into account both the effect of the closure and the load ratio. The validation of the new model was realized using the fatigue crack growth data obtained by Boukharouba, on thick plates containing semi-elliptical defects in three-point bending, for three load ratios ( R = 0.1 , 0.3 and 0.5). One of advantages of the proposed new model is the computation of the SIF range ( ) for all the crack front, not only two points, one at the surface and the second in the depth position, as it is to use. In this case, the evaluation of the crack closure effect becomes more realistic. We believe that the transition, during the fatigue crack propagation, from the plane stress to plane strain or vice versa, leads to an ambiguity in understanding this phenomenon. Support of both states simultaneously, plane strain and plane stress, by the proposed model represents the realistic solution to illustrate the influence of load ratio on the crack, especially for semi-elliptical and semi-circular cracks.

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On crack closure and the notch size effect in fatigue

Cited by 57 publications

References 3 publications

Basic issues in the mechanics of high cycle metal fatigue

Basic issues in the mechanics of high cycle metal fatigue

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New Generalized Fatigue Model: Case of a Semi-elliptical Defect

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