An effective continuum damage mechanics model for creep–fatigue life assessment of a steam turbine rotor

A nonlinear continuum damage mechanics model is proposed to assess the high temperature creep life of a steam turbine rotor, in which the effect of mean stress is taken into account and the damage is accumulated nonlinearly. The model is applied to a 300 MW steam turbine under hot start operation. The results are compared with those from the linear accumulation theory that is dominant in the creep life assessment of steam turbine rotors at present. The comparison results show that the nonlinear continuum damage mechanics model describes the accumulation and development of damage better than the linear accumulation theory.

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Multiaxial Creep-Fatigue Life Prediction on the Rotor of a 1000MW Supercritical Steam Turbine

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-69135 ◽

2012 ◽

Cited By ~ 3

Author(s):

Jianfeng Mao ◽

Weizhe Wang ◽

Yingzheng Liu ◽

Junhui Zhang

Keyword(s):

High Temperature ◽

Steam Turbine ◽

Damage Mechanics ◽

Continuum Damage Mechanics ◽

Continuum Damage ◽

Mechanics Model ◽

Creep Fatigue ◽

Damage Accumulation Model ◽

Multiaxial Creep ◽

Comparison Of The Results

Damage of a high temperature rotor subjected to the creep-fatigue interaction was numerically investigated. Toward that end, a high temperature rotor of a 1000MW supercritical steam turbine was chosen for the study. A continuum damage mechanics model (CDM), which depicts the fatigue-creep interaction, was developed in the present paper. During the practical startup and shutdown processes, the influence of the multiaxial creep-fatigue interaction on strength of the rotor was analyzed in terms of stress, strain and damage. Comparison of the results from linear damage accumulation model (LDA) and CDM demonstrated that CDM was more reasonable to predict the lifetime of the rotor due to the multiaxial creep-fatigue interaction.

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

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420712456513 ◽

2012 ◽

Vol 227 (3) ◽

pp. 216-225 ◽

Cited By ~ 4

Author(s):

Ali Nayebi ◽

Hamid Ranjbar ◽

Hojatollah Rokhgireh

Keyword(s):

Gas Turbine ◽

Damage Mechanics ◽

Continuum Damage Mechanics ◽

Turbine Rotor ◽

Life Assessment ◽

Rotor Steel ◽

Continuum Damage ◽

Mechanics Model

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Continuum damage mechanics-based analysis of creep–fatigue interaction behavior in a turbine rotor

International Journal of Damage Mechanics ◽

10.1177/1056789518775174 ◽

2018 ◽

Vol 28 (3) ◽

pp. 455-477 ◽

Cited By ~ 5

Author(s):

WZ Wang ◽

YZ Liu

Keyword(s):

Damage Mechanics ◽

Maximum Stress ◽

Continuum Damage Mechanics ◽

Turbine Rotor ◽

Von Mises Stress ◽

Temperature Phase ◽

Continuum Damage ◽

Interaction Behavior ◽

Creep Fatigue ◽

The Impact

The aim of this study is to analyze the creep–fatigue interaction behavior of a steam turbine rotor under idealized cyclic thermomechanical loading conditions. A Chaboche model-based material constitutive model is applied to simulate the multiaxial stress–strain behavior in the rotor. Influence of accumulated damage during the whole iterations on the creep–fatigue interaction behavior is described by continuum damage mechanics. Analysis of the temperature and stress variations during the startup phase reveals that the startup phase can be divided into a condensation phase, a high steam flux phase, and an elevated temperature phase and that thermal stress reaches its maximum value in the condensation phase. In addition, creep–fatigue interaction in the rotor leads to a gradual decrease in the maximum stress; furthermore, comparison of the von Mises stress displays that the impact of damage accumulation results in the shift of the location with the maximum stress. Investigation of creep–fatigue damage discloses that the total damage is concentrated on the steam inlet notch zone and the blade groove of the first and third stages.

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