Asymmetric crack wake plasticity – a reason for roughness induced crack closure

Pippan, Reinhard; Strobl, G.; Kreuzer, H.; Motz, Ch.

doi:10.1016/j.actamat.2004.06.014

Cited by 56 publications

(31 citation statements)

References 17 publications

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“…This is particularly true for both the two Ti alloys where a D is around twice d. The condition of a D not much larger than d has to be interpreted as little stress intensity factor closure component ∆ K C . For the Ti alloy loaded at load ratio R = 0.1 the small amount of closure can be addressed to the high load ratio itself, while for the Ti alloy loaded at load ratio R = −1, the reason can be the very high yield strength S Y , Tab.1, which in turn reduces the wake mechanisms responsible for the crack closure [8,9]. For the two aluminum alloys the critical defect size a D ranges from 3 to 4 times the material microstructural size d.…”

Section: Short Crack Threshold Modelsmentioning

confidence: 99%

“…Main contributions were given by Miller [4,5], Miller and O'Donnell [6], Riemelmoser and Pippan [7], and finally a very clear description of the plasticity induced crack closure mechanisms are available in Pippan and Riemelmoser [8] (crack plastic wake closure mechanism under plane strain conditions) and Pippan et al [9] (asymmetric crack plastic wake as the reason for roughness induced closure). The lack of fully developed closure is broadly accepted to be the main mechanistic reason for the physically short crack's faster growth.…”

Section: Introductionmentioning

confidence: 99%

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Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

117

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In metals, during high cycle fatigue on plain specimens, almost the entire fatigue life is spent as short crack initiation and propagation. The fatigue short crack life can be schematically divided into two subsequent phases: microstructurally short crack and physically short crack. Recently, Chapetti proposed a physically short crack threshold and propagation driving force model [1]. In his model the physically short crack behavior is obtained from the long crack propagation, just introducing the reduced threshold due to unsaturated closure. In the present paper the physically short crack propagation is similarly modeled by means of a driving force equation, but independent from the long crack propagation. In this way, a better description of the short crack behavior is provided, however short crack propagation data is required. Physically short crack propagation model parameters were obtained, by fitting experimental data drawn from the literature, for two Aluminum alloys and a Titanium alloy at two different heat treatment conditions and load ratios. By calculating the physically short crack plus long crack propagation, and assuming microstructurally short crack as part of the initiation stage, a purer information about crack initiation can be drawn from the S − N curves, and it is shown in the paper for the investigated materials. A precise crack initiation size and the number of cycles just for initiation are then provided. This information is useful to accurately predict fatigue life for blunt notched and for thick components, where the propagation is much higher than in the small plain specimen. A validation of the model was obtained by predicting the fatigue life of a notched specimen. An accurate prediction was obtained both when the initiation was much smaller than propagation and when almost the entire fatigue life was initiation.

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Section: Short Crack Threshold Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physically short crack propagation in metals during high cycle fatigue

Santus

Taylor

2009

International Journal of Fatigue

117

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“…Plasticity-induced crack closure, roughness induced crack closure and corrosion debris-induced crack closure (often called oxide-induced crack closure) are considered to be the three most important mechanisms responsible for premature fracture surface contact. Despite the vast amount of studies (see for example [2][3][4][5][6][7][8][9][10][11]), there are many unsolved essential questions, for example how does them oxide-induced crack closure in a material depend on crack growth rate, stress ratio, R, environment or temperature, or how can one predict the contribution of roughness-induced crack closure for a certain microstructure as a function of K and R? Important to note is that nearly all these studies are devoted to fatigue crack propagation under small scale yielding.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack closure: From LCF to small scale yielding

Pippan

Grosinger

2013

International Journal of Fatigue

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ABSTRACT. Crack closure has been one of the research topics in the 1980ies and 1990ies. A vast number of papers have been published in this area. However, most of the research work has been devoted to crack propagation under small scale yielding. In this presentation, the different length scale from micro-crack to long cracks and different loading conditions (from low cycle fatigue, LCF, to small scale yielding) affecting crack closure and as a consequence, the near crack tip stress and strain fields are considered. The main focus is on LCF crack closure behaviour which is studied by in-situ scanning electron microscopy. The results demonstrate the importance of crack closure for the explanation of the LCF behaviour. The change of crack closure from LCF to high cycle fatigue and their consequences for lifetime prediction will be discussed.

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“…The local factor k 2 and the related shear displacement u 2 (see Eqs. (3) and (4)) approach a constant value along the crack flanks and, therefore, they are responsible for the long-range part of RICC [9]. On the other hand, the factor k 1 and the related displacements u 1 cause PICC by ''overlapping'' of crack flanks.…”

Section: Plane Strainmentioning

confidence: 96%

“…During the last years, many attempts have been made to incorporate the shielding effects into the LEFM description of the crack-tip stress field. Multiparameter models based on continuum mechanics were recently published [5][6][7][8] and several models dealing with discrete dislocation approaches were also developed, e.g., [1,[9][10][11]. The main advantage of dislocation-based models in comparison with those based on continuum mechanics is their physical transparency that enables us to quantitatively assess both the plasticity-induced and the roughness-induced crack closure (PICC and RICC) components using rather standard materials data.…”

Section: Introductionmentioning

confidence: 99%

Dislocation-based model of plasticity and roughness-induced crack closure

Pokluda

2013

International Journal of Fatigue

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Asymmetric crack wake plasticity – a reason for roughness induced crack closure

Cited by 56 publications

References 17 publications

Physically short crack propagation in metals during high cycle fatigue

Physically short crack propagation in metals during high cycle fatigue

Fatigue crack closure: From LCF to small scale yielding

Dislocation-based model of plasticity and roughness-induced crack closure

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