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Experimental characterisation and computational modelling of cyclic viscoplastic behaviour of turbine steel

Hughes, J.; Rae, Y.; Benaarbia, A.; Hughes, Jeremy; Sun, W.

Authors

J. Hughes

Y. Rae

A. Benaarbia

Jeremy Hughes

W. Sun



Contributors

Yaril Rae
Researcher

Adil Benaarbia
Supervisor

Jeremy Hughes
Supervisor

Wei Sun
Supervisor

Abstract

Fully reversed strain controlled low cycle fatigue and creep-fatigue interaction tests have been performed at ±0.7% strain amplitude and at three different temperatures (400 °C, 500 °C and 600 °C) to investigate the cyclic behaviour of a FV566 martensitic turbine steel. From a material point of view, the hysteresis mechanical responses have demonstrated cyclic hardening at the running-in stage and subsequent, hysteresis cyclic softening during the rest of the material life. The relaxation and energy behaviours have shown a rapid decrease at the very beginning of loading followed by quasi-stabilisation throughout the test. A unified, temperature- and rate dependent viscoplastic model was then developed and implemented into the Abaqus finite element (FE) code through a user defined subroutine (UMAT). The material parameters in the model were determined via an optimisation procedure based on a genetic solver. The multi-axial form of the constitutive model developed was demonstrated by analysing the thermo-mechanical responses of an industrial gas turbine rotor subjected to inservice conditions. A sub-modelling technique was used to optimise the FEA. A 2D global model of the rotor with a 3D sub-model of the second stage of the low pressure turbine were then analysed in turn. The complex transient stress and accumulated plastic strain fields were investigated under realistic thermo-mechanical fatigue loading (start-up and shut-down power plant loads). The sub-model was then used for local analysis leading to identification of potential crack initiation sites for the presented types of blade roots.

Journal Article Type Article
Publication Date 2019-07
Journal International Journal of Fatigue
Print ISSN 0142-1123
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 124
Pages 581-594
APA6 Citation Hughes, J., Rae, Y., Benaarbia, A., Hughes, J., & Sun, W. (2019). Experimental characterisation and computational modelling of cyclic viscoplastic behaviour of turbine steel. International Journal of Fatigue, 124, 581-594. https://doi.org/10.1016/j.ijfatigue.2019.01.022
DOI https://doi.org/10.1016/j.ijfatigue.2019.01.022
Keywords Unified Viscoplasticity; Hysteresis Behaviour; High-Temperature Steel; Turbine Rotor; Finite Element Modelling
Publisher URL https://www.sciencedirect.com/science/article/pii/S0142112319300313
Additional Information This article is maintained by: Elsevier; Article Title: Experimental characterisation and computational modelling of cyclic viscoplastic behaviour of turbine steel; Journal Title: International Journal of Fatigue; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.ijfatigue.2019.01.022; Content Type: article; Copyright: © 2019 Elsevier Ltd. All rights reserved.

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