Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions
Components and structures are designed based in their material’s mechanical properties such as Young's modulus or yield stress among others. Often those properties are obtained under monotonic mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained du...
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doaj-31f0349edfee4ef6b5faea69e44594bf2020-11-24T21:33:03ZengGruppo Italiano FratturaFrattura ed Integrità Strutturale1971-89931971-89932014-10-0183028229210.3221/IGF-ESIS.30.35Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditionsV. Anes0L. Reis1M. Freitas2Instituto Superior Técnico, University of LisbonIDMEC & ICEMS, Instituto Superior Técnico, University of LisbonIDMEC & ICEMS, Instituto Superior Técnico, University of LisbonComponents and structures are designed based in their material’s mechanical properties such as Young's modulus or yield stress among others. Often those properties are obtained under monotonic mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained during the material fatigue life. However, under cyclic loadings, materials tend to change their mechanical properties, which can improve their strength (material hardening) or degrade their mechanical capabilities (material softening) or even a mix of both. This type of material behaviour is the so-called cyclic plasticity that is dependent of several factors such as the load type, load level, and microstructure. This subject is of most importance in design of structures and components against fatigue failures in particular in the case of magnesium alloys. Magnesium alloys due to their hexagonal compact microstructure have only 3 slip planes plus 1 twining plane which results in a peculiar mechanical behaviour under cyclic loading conditions especially under multiaxial loadings. Therefore, it is necessary to have a cyclic elastic-plastic model that allows estimating the material mechanical properties for a certain stress level and loading type. In this paper it is discussed several aspects of the magnesium alloys cyclic properties under uniaxial and multiaxial loading conditions at several stress levels taking into account experimental data. A series of fatigue tests under strain control were performed in hour glass specimens test made of a magnesium alloy, AZ31BF. The strain/stress relation for uniaxial loadings, axial and shear was experimentally obtained and compared with the estimations obtained from the theoretical elastic-plastic models found in the state-of-the-art. Results show that the AZ31BF magnesium alloy has a peculiar mechanical behaviour, which is quite different from the steel one. Moreover, the state of the art cyclic models do not capture in full this peculiar behaviour, especially the cyclic magnesium alloys anisotropy. Further, an analysis is performed to identify the shortcomings inherent to the actual cyclic models in the capture of the magnesium alloys cyclic behaviour. Several conclusions are drawn.http://www.gruppofrattura.it/pdf/rivista/numero30/numero_30_art_35.pdfMagnesium alloysAZ31B-FCyclic elastic-plastic model |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
V. Anes L. Reis M. Freitas |
spellingShingle |
V. Anes L. Reis M. Freitas Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions Frattura ed Integrità Strutturale Magnesium alloys AZ31B-F Cyclic elastic-plastic model |
author_facet |
V. Anes L. Reis M. Freitas |
author_sort |
V. Anes |
title |
Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
title_short |
Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
title_full |
Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
title_fullStr |
Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
title_full_unstemmed |
Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
title_sort |
evaluation of the az31 cyclic elastic-plastic behaviour under multiaxial loading conditions |
publisher |
Gruppo Italiano Frattura |
series |
Frattura ed Integrità Strutturale |
issn |
1971-8993 1971-8993 |
publishDate |
2014-10-01 |
description |
Components and structures are designed based in their material’s mechanical properties such as
Young's modulus or yield stress among others. Often those properties are obtained under monotonic
mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained during the
material fatigue life. However, under cyclic loadings, materials tend to change their mechanical properties, which
can improve their strength (material hardening) or degrade their mechanical capabilities (material softening) or
even a mix of both. This type of material behaviour is the so-called cyclic plasticity that is dependent of several
factors such as the load type, load level, and microstructure.
This subject is of most importance in design of structures and components against fatigue failures in particular
in the case of magnesium alloys. Magnesium alloys due to their hexagonal compact microstructure have only 3
slip planes plus 1 twining plane which results in a peculiar mechanical behaviour under cyclic loading conditions
especially under multiaxial loadings. Therefore, it is necessary to have a cyclic elastic-plastic model that allows
estimating the material mechanical properties for a certain stress level and loading type.
In this paper it is discussed several aspects of the magnesium alloys cyclic properties under uniaxial and
multiaxial loading conditions at several stress levels taking into account experimental data.
A series of fatigue tests under strain control were performed in hour glass specimens test made of a magnesium
alloy, AZ31BF. The strain/stress relation for uniaxial loadings, axial and shear was experimentally obtained and
compared with the estimations obtained from the theoretical elastic-plastic models found in the state-of-the-art.
Results show that the AZ31BF magnesium alloy has a peculiar mechanical behaviour, which is quite different
from the steel one. Moreover, the state of the art cyclic models do not capture in full this peculiar behaviour,
especially the cyclic magnesium alloys anisotropy. Further, an analysis is performed to identify the shortcomings
inherent to the actual cyclic models in the capture of the magnesium alloys cyclic behaviour. Several conclusions
are drawn. |
topic |
Magnesium alloys AZ31B-F Cyclic elastic-plastic model |
url |
http://www.gruppofrattura.it/pdf/rivista/numero30/numero_30_art_35.pdf |
work_keys_str_mv |
AT vanes evaluationoftheaz31cyclicelasticplasticbehaviourundermultiaxialloadingconditions AT lreis evaluationoftheaz31cyclicelasticplasticbehaviourundermultiaxialloadingconditions AT mfreitas evaluationoftheaz31cyclicelasticplasticbehaviourundermultiaxialloadingconditions |
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