On the plastic strain accumulation in notched bars during high-temperature creep dwell

Barbera, D. and Haofeng, C. (2020) On the plastic strain accumulation in notched bars during high-temperature creep dwell. Journal of Mechanics, (doi: 10.1017/jmech.2019.56) (Early Online Publication)

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Abstract

Structural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

Item Type:Articles
Status:Early Online Publication
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barbera, Dr Daniele
Authors: Barbera, D., and Haofeng, C.
Subjects:T Technology > TJ Mechanical engineering and machinery
College/School:College of Arts > School of Culture and Creative Arts > History of Art
College of Science and Engineering > School of Engineering > Systems Power and Energy
Research Group:Material and Manufacturing Research Group
Journal Name:Journal of Mechanics
Publisher:Cambridge University Press
ISSN:1727-7191
ISSN (Online):1811-8216
Published Online:21 February 2020
Copyright Holders:Copyright © 2020 The Society of Theoretical and Applied Mechanics
First Published:First published in Journal of Mechanics 2020
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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