Mechanism of the two stage plastic deformation following an overload in fatigue crack growth

Shimojo, M.; Chujo, M.; Higo, Yakichi; Nunomura, Shigetomo

doi:10.1016/s0142-1123(98)00008-5

Cited by 8 publications

(5 citation statements)

References 13 publications

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“…Refs [7–11]). Recent experimental efforts have been focused on the understanding of the basic retardation mechanisms in order to provide the physical background for the development of crack growth prediction models (e.g, Refs [1–14]). Fatigue crack growth retardation has been attributed to several mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth analysis of 2024 T3 aluminium specimens under aircraft service spectra

Kermanidis

Pantelakis

2001

Fatigue Fract Eng Mat Struct

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The fatigue crack growth behaviour of 2024 T3 aluminium was investigated experimentally. The fatigue experiments were performed under constant stress amplitude, constant amplitude with single and multiple overloads and aircraft service spectra. The fatigue spectra used correspond to the air‐to‐air, air‐to‐ground and instrumentation and navigation flight phases. They were applied for different stress levels. In total 11 different random flight service spectra were examined. The retardation effects caused by the overloads on the fatigue crack growth behaviour and the fatigue crack growth under aircraft service spectra were predicted using an in‐house‐developed code. The code makes use of the strip plastic zone approximation to account for material hardening effects along the path of prospective crack growth. Crack growth is treated incrementally and corresponds to failure of material elements ahead of an existing crack after a certain critical number of fatigue cycles. For the simulation of irregular service spectra by equivalent sequences of distinguished stress cycles a modified rainflow counting method is utilized. Spectrum simulation accounts also for non‐linearity in fatigue damage accumulation and load sequence effects. The computed fatigue curves fit well with the experimental results.

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Section: Introductionmentioning

confidence: 99%

Fatigue crack growth analysis of 2024 T3 aluminium specimens under aircraft service spectra

Kermanidis

Pantelakis

2001

Fatigue Fract Eng Mat Struct

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“…Therefore variable amplitude loading is much more realistic than constant amplitude loading as a reason of fatigue failure. Some workers have studied the simplest case of a single wave overload superimposed on a constant amplitude loading, and changes in load patterns affect crack tip plasticity and hence fatigue crack growth [6][7][8][9][10][11]. Moreover preliminary observation, in a SUS304 stainless steel, indicates that plastic deformation at crack tips exhibits time-dependence and plays an important role on subsequent crack growth behaviors [12,13].…”

Section: Introductionmentioning

confidence: 99%

Room Temperature Creep and its Effect on Fatigue Crack Growth in a X70 Steel with Various Microstructures

Nie

Zhao

2007

KEM

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Fatigue crack growth (FCG) tests have been performed in an X70 steel with various microstructures (respectively in the as-received and the normalized condition). The effect of room temperature creep (RTC) on FCG behavior has been investigated by comparing with single wave overloads (SWOL). The as-received X70 pipeline steel has high FCG rate at the near-threshold region. While at the Paris region, FCG rate seems insensitive to the microstructure. In both conditions, time-dependent deformation is observed at crack tips (i.e., RTC), which increases with increasing stress-intensity-factor. And this deformation has a high value in the normalized state, under identical testing conditions. Both RTC and SWOL can bring subsequent fatigue crack growth a very short initial acceleration before deceleration, whereas the former induces more serious deceleration and retardation, which attributes to more significant crack closures.

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“…may be effective in other materials and/or threshold regimes. Many excellent studies on mechanisms have been published 1–5 and load interactions leading to retardation studied 6–11 …”

Section: Introductionmentioning

confidence: 99%

“…Many excellent studies on mechanisms have been published [1][2][3][4][5] and load interactions leading to retardation studied. [6][7][8][9][10][11] Engineering alloys may show mixed relative rankings when constant amplitude or specially selected variable amplitude spectra are used. 12 The order of tension or compression, 13 or the number of times the overload is repeated 14 influences the growth rate.…”

Section: Introductionmentioning

confidence: 99%

Comparison of retardation behaviour of 2024‐T3 and 7075‐T6 Al alloys

Çelik

Vardar

Kalenderoǧlu

2004

Fatigue Fract Eng Mat Struct

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A B S T R A C T Retardation in fatigue crack growth rate following the application of single and periodic tensile overloads was studied for 2024-T3 and 7075-T6 aluminium alloys. Tests were performed at constant stress and at constant stress intensity factor ranges, at a load ratio of R = 0.1, at a baseline K in the 10-20 MPa √ m range which corresponds to the Paris regime. Overload ratios of 1.3-1.65 were studied with overload spacing, n, varying from 20 to 10 000 cycles. 2024-T3 displayed an order of magnitude higher retardation, N d , due to single tensile overloads compared to 7075-T6. Periodic overloads induced maximum retardation when n/N d ≈ 0.5 for both alloys, the magnitude being only 15% higher for 2024-T3. a = crack length CA = constant amplitude da/dN = crack growth rate K = stress intensity factor K min , K max = minimum and maximum stress intensity factor for base cycling K ol = stress intensity factor corresponding to overload peak M(T) = middle cracked tension specimen n = number of cycles between overloads N = number of cycles N d = number of retarded (delayed) cycles N CA = number of constant amplitude cycles for the crack to grow by an amount equal to the overload-induced plastic zone size OL = overload OLR = overload ratio (K ol /K max ) POL = periodic overload R = stress or load ratio (P min /P max ) S = nominal stress, load/cross-sectional area 2r ol y = plane strain plastic zone size associated with the overload S y = yield strength β = ratio of the constant amplitude crack growth rate to the rate during periodic overloads-retardation factor K = stress intensity factor range corresponding to base cycling, K max -K min K ol = K ol -K min N d = transient portion of the retarded growth ( Fig. 1) S = stress range (= load range/cross-sectional area)

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Mechanism of the two stage plastic deformation following an overload in fatigue crack growth

Cited by 8 publications

References 13 publications

Fatigue crack growth analysis of 2024 T3 aluminium specimens under aircraft service spectra

Fatigue crack growth analysis of 2024 T3 aluminium specimens under aircraft service spectra

Room Temperature Creep and its Effect on Fatigue Crack Growth in a X70 Steel with Various Microstructures

Comparison of retardation behaviour of 2024‐T3 and 7075‐T6 Al alloys

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