Experimental characterisation and computational modelling of cyclic viscoplastic behaviour of turbine steel
Hughes, J.; Rae, Y.; Benaarbia, A.; Hughes, Jeremy; Sun, W.
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|
|Journal||International Journal of Fatigue|
|Peer Reviewed||Peer Reviewed|
|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|
|Keywords||Unified Viscoplasticity; Hysteresis Behaviour; High-Temperature Steel; Turbine Rotor; Finite Element Modelling|
|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.|
IJFATIGUE-D-18-00631R2 (Accepted 29 January 2019)
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