An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation

The present paper is concerned with the formulation of an elasto-plastic strain based approach suitable for assessing fatigue strength of notched components subjected to in-service variable amplitude cyclic loading. The hypothesis is formed that the crack initiation plane is closely aligned with the...

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Main Author: N. Zuhair Faruq
Format: Article
Language:English
Published: Gruppo Italiano Frattura 2016-06-01
Series:Fracture and Structural Integrity
Subjects:
Online Access:https://www.fracturae.com/index.php/fis/article/view/1760
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author N. Zuhair Faruq
author_facet N. Zuhair Faruq
author_sort N. Zuhair Faruq
collection DOAJ
description The present paper is concerned with the formulation of an elasto-plastic strain based approach suitable for assessing fatigue strength of notched components subjected to in-service variable amplitude cyclic loading. The hypothesis is formed that the crack initiation plane is closely aligned with the plane of maximum shear strain amplitude, its orientation and the associated stress/strain quantities being determined using the Maximum Variance Method. Fatigue damage is estimated by applying the Modified Manson-Coffin Curve Method (MMCCM) along with the Point Method (PM). In the proposed approach, the required critical distance is treated as a material property whose value is not affected either by the sharpness of the notch being assessed or by the profile of the load spectrum being applied. The detrimental effect of non-zero mean stresses and degree of multiaxiality of the local stress/strain histories is also considered. The accuracy and reliability of the proposed design methodology was checked against several experimental data taken from the literature and generated under different uniaxial variable amplitude load histories. In order to determine the required local stress/strain states, refined elasto-plastic finite element models were solved using commercial software ANSYS®. This preliminary validation exercise allowed us to prove that the proposed approach is capable of estimates laying within an error factor of about 2. These preliminary results are certainly promising, strongly supporting the idea that the proposed design strategy can successfully be used to assess the fatigue lifetime of notched metallic components subjected to in-service multiaxial variable amplitude loading sequences.
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spelling doaj-art-66ffb7d99b8c49b5b5c022414ef0fcc32025-01-03T00:40:23ZengGruppo Italiano FratturaFracture and Structural Integrity1971-89932016-06-011037An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigationN. Zuhair FaruqThe present paper is concerned with the formulation of an elasto-plastic strain based approach suitable for assessing fatigue strength of notched components subjected to in-service variable amplitude cyclic loading. The hypothesis is formed that the crack initiation plane is closely aligned with the plane of maximum shear strain amplitude, its orientation and the associated stress/strain quantities being determined using the Maximum Variance Method. Fatigue damage is estimated by applying the Modified Manson-Coffin Curve Method (MMCCM) along with the Point Method (PM). In the proposed approach, the required critical distance is treated as a material property whose value is not affected either by the sharpness of the notch being assessed or by the profile of the load spectrum being applied. The detrimental effect of non-zero mean stresses and degree of multiaxiality of the local stress/strain histories is also considered. The accuracy and reliability of the proposed design methodology was checked against several experimental data taken from the literature and generated under different uniaxial variable amplitude load histories. In order to determine the required local stress/strain states, refined elasto-plastic finite element models were solved using commercial software ANSYS®. This preliminary validation exercise allowed us to prove that the proposed approach is capable of estimates laying within an error factor of about 2. These preliminary results are certainly promising, strongly supporting the idea that the proposed design strategy can successfully be used to assess the fatigue lifetime of notched metallic components subjected to in-service multiaxial variable amplitude loading sequences.https://www.fracturae.com/index.php/fis/article/view/1760Notched ComponentsVariable AmplitudeCritical PlaneManson-Coffin Curve
spellingShingle N. Zuhair Faruq
An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
Fracture and Structural Integrity
Notched Components
Variable Amplitude
Critical Plane
Manson-Coffin Curve
title An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
title_full An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
title_fullStr An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
title_full_unstemmed An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
title_short An elasto-plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading: a preliminary investigation
title_sort elasto plastic approach to estimate lifetime of notched components under variable amplitude fatigue loading a preliminary investigation
topic Notched Components
Variable Amplitude
Critical Plane
Manson-Coffin Curve
url https://www.fracturae.com/index.php/fis/article/view/1760
work_keys_str_mv AT nzuhairfaruq anelastoplasticapproachtoestimatelifetimeofnotchedcomponentsundervariableamplitudefatigueloadingapreliminaryinvestigation
AT nzuhairfaruq elastoplasticapproachtoestimatelifetimeofnotchedcomponentsundervariableamplitudefatigueloadingapreliminaryinvestigation