Micromechanics-Based Low Cycle Fatigue Life Prediction Model of ECAPed Aluminum Alloy

Ultrafine-grained aluminum alloys (UFG AA) show great potential in the design of fatigue-resistant lightweight alloys, and the methodology to assess low-cycle fatigue (LCF) life remains to be studied. In this work, a micromechanics-based LCF life prediction model is presented by conducting crystal p...

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Bibliographic Details
Published in:Metals (Basel ) 2022-07, Vol.12 (7), p.1127
Main Authors: Sun, Teng, Xie, Yiji, Pan, Yuchen, Zheng, Zhanguang, Xie, Changji, Huang, Zeng
Format: Article
Language:English
Subjects:
Aluminum base alloys
Axial stress
Crack opening displacement
Crack propagation
Crack tips
crystal plasticity
Damage assessment
Deformation
Deformation mechanisms
Fatigue life
Finite element method
Fracture mechanics
J integral
Life prediction
Low cycle fatigue
low cycle fatigue life prediction
Mathematical models
Metal fatigue
Micromechanics
microscale multiaxial response
Parameters
Plastic deformation
Prediction models
Propagation
Scatter propagation
ultrafine-grained AA6061
Ultrafines
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Summary:Ultrafine-grained aluminum alloys (UFG AA) show great potential in the design of fatigue-resistant lightweight alloys, and the methodology to assess low-cycle fatigue (LCF) life remains to be studied. In this work, a micromechanics-based LCF life prediction model is presented by conducting crystal plasticity finite element simulation (CPFEM). The fatigue indicator parameter (FIP) of maximum accumulated equivalent plastic strain energy, modulated by triaxiality, is developed to assess the material damage in the microstructure. Particularly, a new multiaxial strain parameter is proposed by considering the combined influence of the mean strain and non-proportional cyclic additional hardening effect, and then directly embedding into the cyclic J-integral. Finally, the reformulated Manson-Coffin relationship is theoretically constructed by correlating the crack tip opening displacement to the crack propagation equation. The results show the scatter fatigue life of UFG AA6061 is not only related to the inhomogeneous evolution of plastic deformation but also to the local stress state. Since the proposed approach considers both the deformation mechanisms at the micro-scale and the corresponding macroscopic responses, it can predict the LCF life of UFG AA with reasonable accuracy.
ISSN:2075-4701
2075-4701
DOI:10.3390/met12071127