Probabilistic framework for a microstructure-sensitive fatigue notch factor

Owolabi, Gbadebo; Prasannavenkatesan, Rajesh

doi:10.1016/j.ijfatigue.2010.02.003

Cited by 35 publications

(37 citation statements)

References 44 publications

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“…Following the framework presented in [14], as the volume of each small element tends to zero, Equation (10) can be transformed into…”

Section: Simulation Of Notched Componentsmentioning

confidence: 99%

“…Moreover, the relationship of microstructure to K f , using these constants has proven difficult to establish. Recently, Owolabi et al [14] have established a probabilistic framework based on weakest link theory and extreme-value statistics which incorporates information regarding the peak stress and stress gradient relative to microstructure length scales within a well defined fatigue damage process zone around the notch root. This paper combines the developed probabilistic framework with other existing probabilistic formulations that consider the size distribution and different competing damage mechanisms for aero-engine materials.…”

Section: Introductionmentioning

confidence: 99%

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Application of Weakest Link Probabilistic Framework for Fatigue Notch Factor to Turbine Engine Materials

Okeyoyin¹,

Owolabi²

2013

WJM

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This paper is concerned with the extension of a recently developed probabilistic framework based on Weibull's weakest link and extreme-value statistics to aero-engine materials like titanium alloy and nickel-base super alloys using simulation strategies that capture both the essence of notch root stress gradient and the complexity of realistic microstructures. In this paper, notch size effects and notch root inelastic behavior are combined with probability distributions of microscale stress-strain gradient and small crack initiation to inform minimum life design methods. A new approach which can be applied using crystal plasticity finite element or closed-form solution is also proposed as a more robust approach for determining fatigue notch factor than the existing classical methods. The fatigue notch factors predicted using the new framework are in good agreements with experimental results obtained from literature for notched titanium alloy specimens subjected to uniaxial cyclic loads with various stress ratio.

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“…Following the framework presented in [14], as the volume of each small element tends to zero, Equation (10) can be transformed into…”

Section: Simulation Of Notched Componentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of Weakest Link Probabilistic Framework for Fatigue Notch Factor to Turbine Engine Materials

Okeyoyin¹,

Owolabi²

2013

WJM

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“…This is built on the earlier work of Owolabi et al (2010) that combines computational crystal plasticity with a probabilistic framework to obtain a microscopic fatigue notch factor and associated notch sensitivity index based on the slip distributions in the microstructure at the notch root. In Owolabi et al (2010), 3D computational crystal plasticity was performed on OFHC Cu to assess the degree of heterogeneity of cyclic plastic deformation as a function of notch size and notch root acuity for a range of strain amplitudes below the macroscopic yield strain and different realizations of aggregates of grains with random orientations at the notch root. Statistical information regarding the distributions of stress/strain gradients and the shear-based FIP is obtained providing useful insight into the dependence of fatigue notch factor and associated notch sensitivity index on the heterogeneity inherent in the actual microstructures.…”

Section: Microstructure-dependent Fatigue Notch Factormentioning

confidence: 99%

“…Using the Weibull's weakest link theory and assuming that the nonlocal is a random variable, the microscopic fatigue notch factor is given in Owolabi et al (2010) as…”

Section: Microstructure-dependent Fatigue Notch Factormentioning

confidence: 99%

“…An alternative statistical approach that considers the extreme value portion of the nonlocal distribution (i.e., nonlocal in grains that are above the threshold) within the fatigue damage process zone rather than the Weibull distribution of the nonlocal in all grains within the fatigue damage process zone that was used in Owolabi et al (2010) is used here to develop a new relation for the microstructure-dependent fatigue notch factor. Based on these extreme values, the differences between the in the tail section of the statistical distribution, which are above the threshold th are fitted by an appropriate statistical distribution function.…”

Section: Microstructure-dependent Fatigue Notch Factormentioning

confidence: 99%

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Microstructure-dependent fatigue damage process zone and notch sensitivity index

et al. 2011

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The development of simulation methods for calculating notch root parameters for purposes of estimating the fatigue life of notched components is a critical aspect of designing against fatigue failures. At present, however, treatment of the notch root stress and plastic strain field gradients, coupled with intrinsic length scales of grains or other material attributes, has yet to be developed. Ultimately, this approach will be necessary to form a predictive basis for notch size effects in forming and propagating microstructurally small cracks in real structural materials and components. In this study, computational micromechanics is used to clarify and distinguish process zone for crack formation and microstructurally small crack growth, relative to scale of notch root radius and spatial extent of stress concentration at the notch. A new nonlocal criterion for the fatigue damage process zone based on the distribution of a shear-based fatigue indicator parameter is proposed and used along with a statistical method to obtain a new microstructure-sensitive fatigue notch factor and associated notch sensitivity index, thereby extending notch sensitivity to explicitly incorporate microstructure sensitivity and attendant size effects via probabilistic arguments. The notch sensitivity values obtained for a range of notch root radii using the new statistical approach presented in this

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Microstructure‐Sensitive Probabilistic Fatigue Modeling of Notched Components

Musinski¹

2011

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Probabilistic framework for a microstructure-sensitive fatigue notch factor

Cited by 35 publications

References 44 publications

Application of Weakest Link Probabilistic Framework for Fatigue Notch Factor to Turbine Engine Materials

Application of Weakest Link Probabilistic Framework for Fatigue Notch Factor to Turbine Engine Materials

Microstructure-dependent fatigue damage process zone and notch sensitivity index

Microstructure‐Sensitive Probabilistic Fatigue Modeling of Notched Components

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