A microstructure-based fatigue-crack-initiation model

Chan, Kwai S.

doi:10.1007/s11661-003-0207-9

Cited by 146 publications

(87 citation statements)

References 55 publications

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“…[23] This process requires the collective activity of many dislocations within a grain, which the literature indicates should be on the order of hundreds of nanometers in size. [24] While other researchers have previously noted that crack initiation susceptibility typically decreases with decreasing grain size in metals, [25] we further postulate that the persistent slip mechanism responsible for conventional fatigue crack initiation may be suppressed when the grain size is below a certain threshold, likely on the order of 100 nm or several hundred nanometers. This length scale threshold is between grain sizes that support collective dislocation activity and grain sizes that support individual dislocation activity.…”

Section: Introductionmentioning

confidence: 54%

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Boyce

Padilla

2011

Metall Mater Trans A

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Fatigue failure due to repetitive loading of metallic devices is a pervasive engineering concern. The present work reveals extraordinary fatigue resistance in nanocrystalline (NC) alloys, which appears to be associated with the small (<100 nm) grain size inhibiting traditional cyclic damage processes. In this study, we examine the fatigue performance of three electrodeposited NC Nibased metals: Ni, Ni-0.5Mn, and Ni-22Fe (PERMALLOY). When subjected to fatigue stresses at and above the tensile yield strength where conventional coarse-grained (CG) counterparts undergo low-cycle fatigue failure (<10 4 cycles to failure), these alloys exhibit exceptional fatigue lives (in some cases, >10 7 cycles to failure). Postmortem examinations show that failed samples contain an aggregate of coarsened grains at the crack initiation site. The experimental data and accompanying microscopy suggest that the NC matrix undergoes abnormal grain growth during cyclic loading, allowing dislocation activity to persist over length scales necessary to initiate a fatigue crack by traditional fatigue mechanisms. Thus, the present observations demonstrate anomalous fatigue behavior in two regards: (1) quantitatively anomalous when considering the extremely high stress levels needed to drive fatigue failure and (2) mechanistically anomalous in light of the grain growth process that appears to be a necessary precursor to crack initiation.

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Section: Introductionmentioning

confidence: 54%

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Boyce

Padilla

2011

Metall Mater Trans A

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“…In low cycle fatigue, the number of cycles leading to macrocrack nucleation usually dominates the total life [24]. This is termed as the total life approach, in which the number of cycles to failure is assumed to be the number of cycles to crack initiation.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Simulation of the fatigue behaviour of a power plant steel with a damage variable

Sun

Becker

et al. 2015

International Journal of Mechanical Sciences

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The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract:The fatigue behaviour of a 9Cr power plant steel at a temperature of 600 o C was studied by uniaxial fatigue tests and microstructural analysis using electron microscopy. A continuum damage mechanics apporach was coupled to the constitutive equations of the Chaboche elasto-visco-plastic model to describe the fatigue behaviour of the 9Cr power plant steel at 600 o C. A stress partition method is introduced to understand the fatigue softening behaviour, and used to give an initial estimate of the material constants in the Chaboche model. Further optimisation procedures with plastic strain range dependency of the material constants were introduced in the optimisation procedure in order to accurately predict the material behaviour, especially after damage initiation. An ABAQUS UMAT subroutine was coded to allow the full life cyclic softening behaviour of a power plant component to be accurately predicted in a finite element calculation. The multiaxial capability of the coding is validated against notched bar test data.

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“…The nucleation of a crack was assumed when the energy stored by dislocation pile-up overcomes the surface energy. Chan 10) extended the model to predict the size of the nucleated crack. Manonukul and Dunne 11) proposed a ductility exhaustion model where the local plastic strain range accumulated during a stable cycle is inversely proportional to the number of cycles for crack initiation.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Crack Initiation Simulation in Pure Iron Polycrystalline Aggregate

2016

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A numerical study was conducted to evaluate the fatigue crack initiation stage in pure α-iron. A two-dimensional synthetic polycrystalline aggregate was generated with Voronoi tessellation to represent the microstructure. Low-cycle fatigue experiments under fully reversed strain-controlled loading were conducted for different strain amplitudes. The stable stress-strain hysteresis loops were used to calibrate a non-linear kinematic hardening model for metal plasticity suitable for cyclic simulations. An existing procedure based on the Tanaka-Mura model for fatigue crack initiation was extended to body-centered cubic lattice to account for two orthogonal slip systems as potential crack locations. This procedure was applied for fully reversed fatigue simulations with various stress amplitudes ranging from low-cycle to high-cycle fatigue regime. The effect of the stress level on the crack morphology and the fatigue crack initiation life was evaluated. Finally the applicability and limitations of the proposed procedure was discussed.

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A microstructure-based fatigue-crack-initiation model

Cited by 146 publications

References 55 publications

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Simulation of the fatigue behaviour of a power plant steel with a damage variable

Fatigue Crack Initiation Simulation in Pure Iron Polycrystalline Aggregate

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