Finite Element Modelling of Creep for an Industrial Application

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dc.contributor.advisor Inglis, Helen M.
dc.contributor.coadvisor Pietra, Francesco
dc.contributor.postgraduate Howard, Gareth Johnathan
dc.date.accessioned 2017-05-02T05:35:49Z
dc.date.available 2017-05-02T05:35:49Z
dc.date.created 2017-04-26
dc.date.issued 2017
dc.description Dissertation (MEng)--University of Pretoria, 2017. en_ZA
dc.description.abstract Thermal power stations operate at elevated temperatures and pressures in order to attain maximum available steam energy. At these high temperatures creep becomes a dominant mechanism that needs to be considered. However, for many components, the locations where peak stresses occur are unreachable to apply the commonly used Non-Destructive Testing (NDT) techniques. This encourages the use of Finite Element Analysis (FEA) to better predict the creep state in these complex components. Commonly, creep damage models are used in conjunction with accelerated creep tests to develop material models that can be implemented into a FEA to determine failure. These approaches are often infeasible for industrial decision-making, leaving a gap for more accessible commercially available models to be developed. This paper focuses on using openly available creep data from the Japanese National Institute for Material Science (NIMS). A creep strain model capable of modelling only the primary and secondary creep regimes was then chosen from the ANSYS database to fit this data. In order to fully characterise the experimental data a multi-creep-model approach was adopted that uses a family of creep models, instead of a single creep material model, to characterise the probable range of responses. This methodology was applied to an industrial application, namely an Intermediate Pressure (IP) valve operating under creep-prone conditions. The multi-creep-model approach was incorporated into FEA to analyse the variation in stress distributions. It was interesting to see that a variation of 153% in the creep strain models only resulted in a 21% variation in the relaxed stress. Worst case scenario life time calculations were then conducted using both a time-based Larson-Miller approach and a strain-based ASME code approach. Both sets of results showed that, for the specific component of interest, creep rupture lifetimes were in excess of 3000 years. It was therefore noted that, for the IP valve of interest, the operating temperature and pressure combination were such that no worrisome creep damage occurred. In conclusion, for the specific component analysed, the operating conditions are such that creep based failure will not occur. en_ZA
dc.description.availability Unrestricted en_ZA
dc.description.degree MEng en_ZA
dc.description.department Mechanical and Aeronautical Engineering en_ZA
dc.description.sponsorship NRF en_ZA
dc.description.sponsorship EPPEI en_ZA
dc.identifier.citation Howard, GJ 2017, Finite Element Modelling of Creep for an Industrial Application, MEng Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/60133>
dc.identifier.other A2017
dc.identifier.uri http://hdl.handle.net/2263/60133
dc.language.iso en en_ZA
dc.publisher University Of Pretoria
dc.rights © 2017 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. en_ZA
dc.subject Ansys en_ZA
dc.subject Creep en_ZA
dc.subject Finite Element Analysis en_ZA
dc.subject Life Prediction en_ZA
dc.subject NIMS Experimental Data en_ZA
dc.subject UCTD
dc.title Finite Element Modelling of Creep for an Industrial Application en_ZA
dc.type Dissertation en_ZA


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