On the Relation Between Stable Crack Growth and Fatigue

Kaiser, Sten

doi:10.1111/j.1460-2695.1983.tb01137.x

Cited by 34 publications

(17 citation statements)

References 4 publications

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“…These results do appear to support the type of analysis proposed by Kaiser [1] allowing a superposition of cycling and tearing crack extension to be directly summed as in (9). Cyclic growth rates are not strongly affected by ductile plastic tearing steps and the J-R curve is only slightly elevated by the presence of cycling if the cyclic R ratio is small.…”

Section: Discussionsupporting

confidence: 74%

“…To analyze just the tearing component of crack extension for the cycle/tear specimens the procedure of Kaiser [1] was used in that the load cycles as shown on Fig. 6 were simply ignored giving "envelope" load displacement curves as shown on Fig.…”

Section: Analysis Of the Tearing Crack Growth Componentmentioning

confidence: 99%

“…Two studies of the effects of such unloadings were reported previously [1,2] in which deep unloadings, including full unloadings, were applied repeatedly during the course of the J resistance curve evaluation. It was shown that such cycles could distinctly alter the J/,.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of interaction effects between ductile tearing and intense fatigue cycling

Joyce

Culafic²

1988

Int J Fract

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The objective of this work was to develop an initial understanding of interaction effects which occur during complex loading in the elastic-plastic regime. A simple superposition model is presented for the accumulation of crack extension from ductile tearing and intense elastic-plastic cycling. Baseline cyclic data and baseline J based resistance curve data was developed for an HSLA steel using compact specimen geometries. Then a series of specimens were tested with alternate ductile tear and intense cyclic loadings.Conclusions from the analysis of these specimens were that the cyclic crack growth rate resulting from the intense cyclic intervals is only slightly elevated by the presence of ductile tearing load steps and is very constant over cyclic growth periods of 1 mm extent showing little acceleration or decceleration due to the ductile tearing step. Also demonstrated was that the ductile tearing resistance as measured by the J integral is almost unaffected by periods of intense cyclic loading if the R ratio is small and is inceased as the R ratio approaches 0.5. Both measured effects would lead to conservative results if the simple superposition model was used to predict the plastic cycling punctuated by occasional ductile tearing steps.

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Section: Discussionsupporting

confidence: 74%

Section: Analysis Of the Tearing Crack Growth Componentmentioning

confidence: 99%

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Characterization of interaction effects between ductile tearing and intense fatigue cycling

Joyce

Culafic²

1988

Int J Fract

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“…Here a different approach is adopted, and it is assumed that the contribution of stable tearing to the fatigue crack growth rate is determined by the conditions at the maximum load, PmaX. The crack growth resistance curve of the material is assumed to be unchanged by previous cyclic loading history and crack growth an assumption supported by the recent work of Kaiser [9]. These assumptions are also consistent with the monotonic crack growth model proposed by Wnuk [14].…”

Section: Ductile Failure Lindley and Mccartney [8]mentioning

confidence: 96%

Fatigue Crack Growth Laws for Brittle and Ductile Materials Including the Effects of Static Modes and Elastic‐plastic Deformation

Chell

1984

Fatigue Fract Eng Mat Struct

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A fatigue crack growth damage accumulation model is used to derive laws for the fatigue crack growth rates of brittle and ductile materials. The damage accumulated during cyclic loading is assumed to be proportional to the cyclic change in the plastic displacement in the crack tip yielded zone. The static mode contribution to the fatigue damage is assumed to be proportional to some power of the crack tip displacement. The laws are applicable in either the small or large scale yielding regimes provided that the stress ratio remains positive. Static modes are assumed to be controlled by the fracture toughness value in brittle materials, and by the gradient of the crack growth resistance curve in ductile materials. In the analysis of ductile materials it is assumed that the crack growth resistance of the material is not significantly altered by fatigue crack growth.The growth rate equations are expressed in terms of the near field value of the J-integral, i.e. the value which would be calculated from assuming the material deformed in a non-linear elastic manner during the increasing load part of the fatigue cycle. Examples are given of the predictions of the growth law for ductile materials. It is predicted that after the initiation of stable tearing the crack growth rate, when expressed in terms of the cyclic change in the stress intensity factor, depends on both the structural geometry and the degree of crack tip plastic deformation. In both brittle and ductile materials the fatigue crack growth rate is predicted to accelerate as the failure criteria relevant to static crack instability are approached. NOMENCLATURE da/dN = fatigue crack growth rate Aa,da = increment of crack extension Aa,,da, = tear component of Aa and 6a 6af = fatigue component of 6a f ( a / w ) = function defining the plastic collapse stress m = exponent in Paris-Erdogan growth law s = size of fatigue plastic zone w = specimen width A = constant in Paris-Erdogan growth law D = crack tip damage parameter D, = critical value of D AD = cyclic change in D E = Young's modulus F, = a dimensionless constant related to the fatigue process zone length E 237 F t M S 1 4 A 238 G. G. CHELL F ( z ) = a function defining the plastic displacement G = strain energy release rate J = J-integral J, = value of J at initiation of ductile tear Jlc = initiation value of J determined in a toughness test J, = critical value of J for fast fracture .Imax = J corresponding to maximum load AJ =cyclic change in J JR = crack growth resistance value of J J, = saturation JR value K = stress intensity factor K,,, = K at maximum load Kmin = K at minimum load K,, = fracture toughness AK = cyclic change in K K, = K/K,c M = constant relating J to CD N = number of fatigue cycles P,,, = maximum load P,,, = minimum load R = Pm,n/Pmax s, = a/ol T = tearing modulus T,,, = T at maximum load T,,, = T evaluated from J R resistance curve T,,,, = T,,, at initiation of tear a = constant relating D to (D p = exponent relating D to CD S = material constant related to fatigue process zone E = fat...

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“…This increase may be attributed to static fracture modes, for example, from ductile tearing. Previous studies show that for some materials the interaction between the fatigue mode and static modes is negligible, [21][22][23] and the increased crack growth due to ductile tearing may be simulated by an amplification factor obtained from a monotonic J R curve:…”

Section: Introductionmentioning

confidence: 99%

On numerical analysis of damage evolution in cyclic elastic‐plastic crack growth problems

Skallerud

Zhang

2001

Fatigue Fract Eng Mat Struct

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Structures subjected to severe cyclic loading may fail due to low cycle fatigue. During the latter part of the fatigue life the crack growth rate may increase due to crack growth from static failure modes. This was investigated numerically by Skallerud and Zhang (Int. J. Solids Struct. 34, 3141–3161, 1997) for a butt‐welded plate with a circular crack growing from the centre of the weld. The weld material was slightly overmatching, and for simplicity, base material properties were employed in the finite element model. The predicted crack growth rate was significantly underpredicted in the early part of crack growth. In the present investigation, more detailed material modelling was used, and some metallurgical aspects were addressed. The fatigue part of the crack growth was determined by using the computed cyclic J‐integral, and the static mode crack growth from ductile tearing is determined from computations accounting for void nucleation/growth/coalescence by means of a modified Gurson–Tvergaard model.

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On the Relation Between Stable Crack Growth and Fatigue

Cited by 34 publications

References 4 publications

Characterization of interaction effects between ductile tearing and intense fatigue cycling

Characterization of interaction effects between ductile tearing and intense fatigue cycling

Fatigue Crack Growth Laws for Brittle and Ductile Materials Including the Effects of Static Modes and Elastic‐plastic Deformation

On numerical analysis of damage evolution in cyclic elastic‐plastic crack growth problems

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