Analysis of unified continuum damage mechanics model of gas turbine rotor steel: Life assessment

Nayebi, A.; Ranjbar, Hamid; Rokhgireh, H.

doi:10.1177/1464420712456513

Cited by 9 publications

(8 citation statements)

References 12 publications

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“…Lemaitre-Chaboche viscoplastic model is commonly employed (Chaboche et al (1979)). Several authors have applied this model to study the responses of some turbine rotors under fatiguecreep conditions (Nayebi et al (2013); Benaarbia et al (2018a)). Moreover, multiple viscosity functions are available in literature to model the viscoplastic flow, a number of which have been reviewed by Chaboche (Chaboche (2008)).…”

Section: Introductionmentioning

confidence: 99%

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

Rae

Benaarbia

Hughes³

et al. 2019

International Journal of Fatigue

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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 visco-plastic 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 thermomechanical responses of an industrial gas turbine rotor subjected to in-service 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 shutdown 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.

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Section: Introductionmentioning

confidence: 99%

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

Rae

Benaarbia

Hughes³

et al. 2019

International Journal of Fatigue

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“…During the start-up and operation of steam turbine, the thermal stress and mechanical stress on the rotor gradually change, involving many process variables, including steam pressure, steam temperature, steam temperature change rate, rotor speed, etc., which belongs to the transient condition of steam turbine [3]. The variation of these variable parameters has a direct impact on the service life of turbine rotor metal materials.…”

Section: Research Background and Research Statusmentioning

confidence: 99%

Damage model of turbine rotor based on DPLS

Dong¹,

Qin²,

Sun³

2021

Ann Syst Biol

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In today's society, the development of electric power industry is one of the important conditions for the economic construction of a country. Therefore, it is of great theoretical significance and value to carry out the research on the damage assessment of turbine rotor. The damage of the turbine rotor is directly related to the process quality, material performance, operation conditions of the equipment itself, and also closely related to the performance of the controller. According to the existing data and starting conditions, a dynamic partial least square prediction model is established and analyzed in this paper, so as to effectively evaluate the stress and damage of the turbine rotor. Before the establishment of dynamic partial least squares model, people study the change law of stress value and damage value mainly through complex mathematical formulas and inconvenient fi nite element analysis software. After the establishment of dynamic partial least squares model, the staff only need to input the input data (speed, temperature, back pressure) to the model to get the stress. The function is also realized in this paper.

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“…Chaboche proposed a phenomenological based unified model which combined isotropic and kinematic hardening variables in a viscoplasticity-flow rule, taking into account cyclic hardening/softening and the Bauschinger effect [12]. The model has been used extensively by many authors to study the responses of materials under creep-fatigue conditions and shows a good agreement with the experimental results [13][14][15].…”

Section: Introductionmentioning

confidence: 96%

A lifing method based on R5 and viscoplasticity modelling and its application to turbine rotor under thermomechanical loading

Bonetti

Hadjipakkos

Rae

et al. 2020

Engineering Failure Analysis

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An integrated life assessment procedure for structures operating under thermomechanical loading has been developed. The methodology uses a viscoplasticity based framework combined with the R5 life assessment code. The viscoplastic constitutive model used for the stress-strain analysis is derived from the Chaboche-Lemaitre formulation that allows to directly obtain the required parameters for the R5 assessment as stress relaxation per cycle and the elastic follow-up factor. The R5 procedure is therefore significantly simplified. The proposed life assessment procedure is demonstrated on a martensitic steel (FV566) industrial gas turbine rotor under a typical start up -shut down operation. The effect of creep-fatigue interaction at different locations within the rotor structure is assessed and the remaining life at each location is calculated. A sensitivity study is performed at half load, which shows an increase in lifetime of the rotor.

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Analysis of unified continuum damage mechanics model of gas turbine rotor steel: Life assessment

Cited by 9 publications

References 12 publications

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

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

Damage model of turbine rotor based on DPLS

A lifing method based on R5 and viscoplasticity modelling and its application to turbine rotor under thermomechanical loading

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