Effect of periodic underloads on fatigue crack growth in three steels used in hydraulic turbine runners

Hassanipour, Meysam; Verreman, Yves; Lanteigne, J.; Chen, J.Q.

doi:10.1016/j.ijfatigue.2015.11.027

Cited by 16 publications

(7 citation statements)

References 27 publications

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“…19 Additionally, literature has indicated that such underloads usually have the effect of accelerating the following crack growth. [22][23][24][25] Other studies on AA7050-T7451 have shown that the acceleration caused by underloads is at a maximum for small crack lengths (<1 mm) and reduces as the crack grows. 26 It may be that any fractographic features that correlate with this acceleration would similarly be diminished as the crack grows, be it in an absolute or a comparative manner.…”

Section: Introductionmentioning

confidence: 99%

An analysis of fatigue crack features at various crack lengths through mating fracture surface pairs

Field,

Kandare,

Dixon

et al. 2024

Fatigue Fract Eng Mat Struct

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This paper presents a novel high‐resolution direct analysis of mating AA7050‐T7451 fracture surfaces at crack lengths from 0.1 to 1.3 mm (Kmax of 4.51 to 16.39 MPa√m) for the purpose of analyzing the fatigue growth mechanisms. The various fractographic features observed at these crack lengths were then compared to the known accelerative effects of an applied loading sequence that contained underloads at regular intervals. A correlation was found between some of the observed features and the local fatigue crack growth rate. This study provides new insight into the prominent mechanisms that dictate crack growth rate and ultimately should assist with developing crack growth prediction methods that more accurately represent the physics of the fatigue crack growth mechanisms.

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Section: Introductionmentioning

confidence: 99%

An analysis of fatigue crack features at various crack lengths through mating fracture surface pairs

Field,

Kandare,

Dixon

et al. 2024

Fatigue Fract Eng Mat Struct

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“…It has been noted that crack acceleration is likely to be manifested in cases where the baseline fatigue loading is positive, i.e., positive loading ratio R . Furthermore, higher crack acceleration occurs at higher baseline loading ratio . In addition, the extent of such acceleration, if present, is dependent on the material cyclic hardening behavior and the magnitude of UL with respect to the steady‐state cyclic load.…”

Section: Introductionmentioning

confidence: 99%

Elucidating the Mechanism of Fatigue Crack Acceleration Following the Occurrence of an Underload

et al. 2016

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Fatigue Crack Growth Rate (FCGR) is altered by a single anomalous load exceeding cyclic maximum (Overload) or compressive load below cyclic minimum (Underload). The authors study fatigue crack acceleration due to a single compressive Underload using residual stress mapping (by synchrotron XRD) and crack closure analysis (by DIC). The relative influence and duration of these two principal causes of FCGR alteration are revealed. Validated FEA model is used for parametric analysis of the effect of baseline cyclic loading ratio and magnitude of Underload on the cyclic J-integral.

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“…In the literature many papers can be found on the topic of the effects of underloads. However, a majority of them, e.g., [ 15 , 16 , 17 , 18 ], are related to intense compressive overloads or a reduced mean load (see the underloads of the type A and B in Figure 3 a,b). In other words, “underload” means a significant reduction (shift to negative values) of the minimal load.…”

Section: Introductionmentioning

confidence: 99%

Effect of Underload Cycles on Oxide-Induced Crack Closure Development in Cr-Mo Low-Alloy Steel

et al. 2021

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Underload cycles with small load amplitudes below the fatigue crack growth threshold are dominantly considered as insignificant cycles without any influence on fatigue lifespan of engineering structural components. However, this paper shows that in some cases these underload cycles can retard the consequent crack propagation quite significantly. This phenomenon is a consequence of oxide-induced crack closure development during cyclic loading below the threshold. The experimentally described effect of fatigue crack growth retardation was supported by measurement of the width and the thickness of the oxide debris layer using the EDS technique and localized FIB cuts, respectively. Both the retardation effect and the amount of oxide debris were larger for higher number and larger amplitudes of the applied underload cycles. Crack closure measurement revealed a gradual increase of the closure level during underload cycling. Specimens tested in low air humidity, as well as specimens left with the crack open for the same time as that needed for application of the underload cycles, revealed no retardation effect. The results can improve our understanding of environmental effects on fatigue crack propagation and understanding the differences between the results of laboratory testing and the fatigue lives of components in service.

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Effect of periodic underloads on fatigue crack growth in three steels used in hydraulic turbine runners

Cited by 16 publications

References 27 publications

An analysis of fatigue crack features at various crack lengths through mating fracture surface pairs

An analysis of fatigue crack features at various crack lengths through mating fracture surface pairs

Elucidating the Mechanism of Fatigue Crack Acceleration Following the Occurrence of an Underload

Effect of Underload Cycles on Oxide-Induced Crack Closure Development in Cr-Mo Low-Alloy Steel

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