The Fictitious Radius as a Tool for Fatigue Life Estimation of Notched Elements

Robak

Fatigue Fract Eng Mat Struct

2014

The work presents verification of Neuber's fictitious radius method, used in fatigue life calculation of notched elements and welded joints. Stress values, calculated according with fictitious radius method, were compared with smooth specimens Basquin fatigue curves, and number of cycles was read. However, obtained calculated number of cycles of fatigue life does not correspond to experimental fatigue life, especially in a low cycle fatigue range. Hence, different equivalent microstructural length values were calculated for different loading levels. It was observed that equivalent microstructural length depends on loading level and type of loading. Finally, equivalent microstructural length was presented in a linear regression equation, as dependant on loading level and its relation to yield strength.

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“…For tensioning, Eq. 10 adopts the following form: ρ Ã ¼ 8:62Á σ a;n;notch σ Y À 2:02 (11) and for bending ρ Ã ¼ 0:76Á σ a;n;notch σ Y À 0:09:…”

Section: T H E E Q U I V a L E N T M I C R O S T R U C T U R A L L E mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Determining fatigue life of bent and tensioned elements with a notch, with use of fictitious radius

Robak

Fatigue Fract Eng Mat Struct

2014

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“…However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading. However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading.…”

Section: Introductionmentioning

confidence: 99%

“…Both the replacement value of the microstructural length and many other known lengths determining the fatigue zone are represented as constants by scientists. However, as demonstrated by, 25,27,28 this zone depends on the level and type of loading. This is an important observation, because stress calculations are usually performed for the elastic material model in some studies, and there is no clear determination of the number of cycles to crack initiation.…”

Section: Introductionmentioning

confidence: 99%

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

Robak

Fatigue Fract Eng Mat Struct

2016

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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Fatigue life estimation of notched elements with use of non-local volumetric method

International Journal of Fatigue

2014