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 t...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2016-07-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero37/numero_37_art_49.pdf |
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| Summary: | 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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| ISSN: | 1971-8993 1971-8993 |