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, 36(2), pp. 167-176. (doi: 10.1017/jmech.2019.56)

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: Published
• 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 36(2):167-176
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher