Advanced volumetric method for fatigue life prediction using stress gradient effects at notch roots

Adib-Ramezani, H.; Jeong, Jena

doi:10.1016/j.commatsci.2006.08.017

Cited by 67 publications

(27 citation statements)

References 29 publications

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“…4. The application of the micro-dilatation theory to the notch fracture mechanics (Boukharouba et al, 1995;Qylafku et al, 1999;Pluvinage and December, 2003;Adib and Pluvinage, 2003;Adib-Ramezani and Jeong, 2007) would be of great interest. The notch fracture mechanics is mainly proposed and applied for the homogeneous materials like metals and some composites by means of the stress field intensity approach (Weixing, 1992;Weixing, 1993;Shang et al, 2001).…”

Section: Synthesis and Outlooksmentioning

confidence: 99%

Non-linear elastic micro-dilatation theory: Matrix exponential function paradigm

Ramézani

Jeong²

2015

International Journal of Solids and Structures

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a b s t r a c tIn the present paper, the micro-dilatation theory or void elasticity is extended to both large displacement and large dilatation. Firstly, the deformation gradient tensor has been freshly defined by means of the matrix exponential function. The newly defined relation for the deformation gradient has painstakingly investigated for the uniqueness, decomposition issues as well as objectivity and isotropy considerations. The relation of the displacement gradient and deformation gradient tensor is brought via the matrix logarithm function. The micro-dilatation theory constitutive laws are derived using the thermodynamic principles under the zero-centrosymmetric, weakly-centrosymmetric and fully-centrosymmetric cases. These cases have been derived and scrutinized by the numerical experiments. To achieve this assignment, the basic loadings are taken into account, e.g. the hydrostatic loading, simple traction and shear. Some conclusions and outlook pertaining to the above-mentioned cases and variable bulk density have thereafter discussed.

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Section: Synthesis and Outlooksmentioning

confidence: 99%

Non-linear elastic micro-dilatation theory: Matrix exponential function paradigm

Ramézani

Jeong²

2015

International Journal of Solids and Structures

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“…Motivated by microscopic observations that fatigue failure occurs by damage accumulation in a finite notch root damage process zone, which can encompass several grains, numerous research studies have explored estimation of the fatigue notch factor as well as fatigue strength as a function of an average stress over the fatigue damage process zone (Neuber 1961;Beremin 1983;Weixing 1992;Qylafku et al 1998Qylafku et al , 1999Ren and Nicholas 2003;Ranganathan et al 2004;Delahay and Palin-Luc 2006;Doudard et al 2007;Adib-Ramezani and Jeong 2007).These methods consider the average stress value over a significant length scale at the notch root when analyzing fatigue potency of a notched component. One of these methods, called the the point method, uses a specific distance known as the critical distance from the notch-root which may correspond to a grain size (Neuber 1958) or plastic zone size (Peterson 1959) and its corresponding average stress level to predict K f and fatigue life of notched components.…”

Section: Introductionmentioning

confidence: 99%

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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“…11,29,36,37 This method of calculation is justified because the value of stress already at low loads at the tip of the notch exceeds the cyclic yield point, which affects the calculated size of the fatigue zone. Only calculations using the nonlinear analysis which take into account the cyclic material properties should be used in order to obtain the effective stress values, which take into account the hardening of a material.…”

Section: Introductionmentioning

confidence: 99%

Non‐local line method for notched elements with use of effective length calculated in an elasto‐plastic condition

Krzyżak

Robak

Łagoda

2016

Fatigue Fract Eng Mat Struct

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The paper presents a non‐local line method used to the fatigue life calculation of notched elements. The presented method is based on the concept of an effective length which determines the size of the equivalent fatigue zone. Effective values of normal stress calculated in the critical plane with a weight function were applied when determining the equivalent fatigue zone. Simulation studies were performed for two types of steel and two types of loading. Five different series of tests and simulations were used. Experimental studies were carried out for 40 HM‐T and EA4T steels. These materials are used in railway industry, including the manufacturing of coupling bars. The notched test specimens contained notches with a tip radius of 0.2, 0.5, 0.8 and 1 mm. Stress calculations were performed using the finite element method by adopting cyclic material properties described by the model of a multi‐linear hardening. Non‐local calculations were performed in a defined critical plane for normal stress distribution and a weight function. As a result, the function of variation of the effective length depending on the loading level and geometry of the notch has been determined.

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Advanced volumetric method for fatigue life prediction using stress gradient effects at notch roots

Cited by 67 publications

References 29 publications

Non-linear elastic micro-dilatation theory: Matrix exponential function paradigm

Non-linear elastic micro-dilatation theory: Matrix exponential function paradigm

Microstructure-dependent fatigue damage process zone and notch sensitivity index

Non‐local line method for notched elements with use of effective length calculated in an elasto‐plastic condition

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