A transgranular fatigue crack growth model based on restricted slip reversibility

Wu, Xijia; Koul, A. K.; Krausz, A. S.

doi:10.1007/bf02668205

Cited by 38 publications

(8 citation statements)

References 32 publications

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“…Frong and Thomas and Wu, Koul and Krausz used the concept of irreversible slip at the cracktip resulting in the zigzag crack extension during the stage II growth period (Fig. ).…”

Section: Dislocation Irreversibility Modelsmentioning

confidence: 99%

Mechanisms of fatigue crack growth – a critical digest of theoretical developments

Chowdhury

Şehitoğlu

2016

Fatigue Fract Eng Mat Struct

127

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A B S T R A C T Recent advances in the processing technology are permitting the manufacture of novel metallic materials with superior fatigue properties via microstructure tailoring. In the light of these promising developments, there is a rising need for establishing a synergy between state-of-the-art experimental characterizations and physically based theoretical underpinnings. A revisit to the existing predictive literature is thus a timely requirement prior to furthering new design guidelines against cyclic damage. To that end, this paper recounts an overview of the key mechanistic and analytical theories on the fatigue crack growth mechanisms. Emphasis is placed on categorizing the proposed modelling endeavours based on their fundamental principles. In doing so, contributions and limitations thereof are carefully examined on the basis of most updated experimental revelations. The objective is to provide a perspective to the current generation of engineers and researchers alike. This concise yet critical narrative would essentially assist in formulating even more advanced microstructure-damage relationships in the modern context. A commentary is added at the end outlining the promising avenues for future research.CTOD, FCG = crack tip opening displacement, fatigue crack growth MD, DFT = molecular dynamics, density functional theory RVE = representative volume element LEFM, EPFM = linear elastic and elastic plastic fracture mechanics E, H = Young's modulus, plastic modulus GB = grain boundary K max , K min , K open , = maximum, minimum and opening stress-intensity factors K c = fracture toughness under mode I loading ΔK eff th , ΔK th = (effective) threshold stress intensity factor range da/dN = fatigue crack growth rate per cycle (a is the crack length and N is the number of cycles) L deflect , θ deflect = length and angle of a deflected crack respectively θ = angle between slip and crack paths σ yield , σ cyclic yield , σ fracture = monotonic, cyclic yields strengths and static fracture strength σ ′ f , ε ′ f = strength and ductility coefficient in Coffin-Manson-Basquin rule: Δε plastic ¼ 2ε ′ f 2N f ð Þ c σ eff , σ hydro = effective and hydrostatic stress ρ * = effective radius of a sharp crack ρ slip , _ ρ vacancy , ρ interface = dislocation density, vacancy generation rate and interface density P H 2 , P O 2 = partial pressures of hydrogen and oxygen m, C = Paris exponent, Paris proportionality constant m Schmid = Schmid factor τ friction , τ forward friction , τ reverse friction = friction (Peierls) stress for free (unobstructed), forward and reverse dislocation glide

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“…Frong and Thomas and Wu, Koul and Krausz used the concept of irreversible slip at the cracktip resulting in the zigzag crack extension during the stage II growth period (Fig. ).…”

Section: Dislocation Irreversibility Modelsmentioning

confidence: 99%

Mechanisms of fatigue crack growth – a critical digest of theoretical developments

Chowdhury

Şehitoğlu

2016

Fatigue Fract Eng Mat Struct

127

View full text Add to dashboard Cite

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“…Pippan studied the force required to emit dislocations at the crack tip and related the quantity of emitted dislocations that do not fully reverse to the crack growth rate [17,18]. Wu et al related the plastic strain ahead of the crack tip, due to slip irreversibility, to the fatigue crack growth rate [19]. A technique using DIC has been developed to determine the quantity of residual crack tip plastic strain and has been demonstrated for several materials at room temperature [7,20].…”

Section: Introductionmentioning

confidence: 99%

High temperature fatigue crack growth of Haynes 230

Pataky¹,

Şehitoğlu²,

Maier

2013

Materials Characterization

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“…3 does not include the plasticity ahead of the crack tip, but contains terms for the shear stress along the crack propagating direction and the principal stress state. The majority of the existing metrics, describing fatigue crack propagation direction and rate, available in the literature Table 2 are proportional to the accumulated microplasticity ahead of the crack tip 21,[32][33][34][35]48 ; however, this assumption is not supported by the available data. The comparison of Fig.…”

Section: Discussionmentioning

confidence: 57%

Using machine learning and a data-driven approach to identify the small fatigue crack driving force in polycrystalline materials

Rovinelli¹,

Sangid²,

Proudhon³

et al. 2018

npj Comput Mater

144

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The propagation of small cracks contributes to the majority of the fatigue lifetime for structural components. Despite significant interest, criteria for the growth of small cracks, in terms of the direction and speed of crack advancement, have not yet been determined. In this work, a new approach to identify the microstructurally small fatigue crack driving force is presented. Bayesian network and machine learning techniques are utilized to identify relevant micromechanical and microstructural variables that influence the direction and rate of the fatigue crack propagation. A multimodal dataset, combining results from a high-resolution 4D experiment of a small crack propagating in situ within a polycrystalline aggregate and crystal plasticity simulations, is used to provide training data. The relevant variables form the basis for analytical expressions thus representing the small crack driving force in terms of a direction and a rate equation. The ability of the proposed expressions to capture the observed experimental behavior is quantified and compared to the results directly from the Bayesian network and from fatigue metrics that are common in the literature. Results indicate that the direction of small crack propagation can be reliably predicted using the proposed analytical model and compares more favorably than other fatigue metrics.

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A transgranular fatigue crack growth model based on restricted slip reversibility

Cited by 38 publications

References 32 publications

Mechanisms of fatigue crack growth – a critical digest of theoretical developments

Mechanisms of fatigue crack growth – a critical digest of theoretical developments

High temperature fatigue crack growth of Haynes 230

Using machine learning and a data-driven approach to identify the small fatigue crack driving force in polycrystalline materials

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