Creep-Fatigue Interaction of Steam Turbine Rotors Using Continuum Damage Mechanics

2022 ◽  
Author(s):  
Suvadeep Sen ◽  
Badri Prasad Patel
Keyword(s):  
Steam Turbine ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Creep Fatigue ◽  
Turbine Rotors

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

2012 ◽  
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.

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

2018 ◽  
Vol 28 (3) ◽  
pp. 455-477 ◽  
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.

Analysis of Multi-Axial Creep–Fatigue Damage on an Outer Cylinder of a 1000 MW Supercritical Steam Turbine

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Weizhe Wang
Keyword(s):  
Steam Turbine ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Hydrostatic Stress ◽  
Fatigue Behavior ◽  
Axial Stress ◽  
Outer Cylinder ◽  
Continuum Damage Mechanics ◽  
Transfer Coefficients ◽  
Creep Fatigue

A multi-axial continuum damage mechanics (CDM) model was proposed to calculate the multi-axial creep–fatigue damage of a high temperature component. A specific outer cylinder of a 1000 MW supercritical steam turbine was used in this study, and the interaction of the creep and fatigue behavior of the outer cylinder was numerically investigated under a startup–running–shutdown process. To this end, the multi-axial stress–strain behavior of the outer cylinder was numerically studied using Abaqus. The in-site measured temperatures were provided to validate the heat transfer coefficients, which were used to calculate the temperature field of the outer cylinder. The multi-axial mechanics behavior of the outer cylinder was investigated in detail, with regard to the temperature, Mises stress, hydrostatic stress, multi-axial toughness factor, multi-axial creep strain, and damage. The results demonstrated that multi-axial mechanics behavior reduced the total damage.

Continuum Damage Mechanics: Part II—Damage Growth, Crack Initiation, and Crack Growth

1988 ◽  
Vol 55 (1) ◽  
pp. 65-72 ◽  
Author(s):  
J. L. Chaboche
Keyword(s):  
Crack Initiation ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Damage Growth ◽  
Strain Behavior ◽  
Brittle Damage ◽  
Creep Fatigue ◽  
Growth Crack ◽  
Growth Equations

Continuum Damage Mechanics (CDM) allows the description of the influence of damage on the stress-strain behavior of materials. In the present part, some practical damage growth equations are reviewed for creep, fatigue, creep-fatigue interaction, ductile damage, and brittle damage. The capabilities of CDM to improve both the crack initiation and crack propagation predictive tools are then discussed. Particular attention is given to the new developments of the “local approaches to fracture.”

A Continuum Damage Mechanics-Based Viscoplastic Model of Adapted Complexity for High-Temperature Creep–Fatigue Loading

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Weizhe Wang ◽  
Patrick Buhl ◽  
Andreas Klenk ◽  
Yingzheng Liu
Keyword(s):  
Damage Mechanics ◽  
Fatigue Behavior ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Material Model ◽  
Material Behavior ◽  
Continuum Damage ◽  
Loading Test ◽  
Constitutive Material Model ◽  
Creep Fatigue

A continuum damage mechanics (CDM) based viscoplastic constitutive model is established in this study to describe the fully coupling of creep and fatigue behavior. The most significant improvement is the introduction of a continuum damage variable into the constitutive equations, instead of considering creep damage and fatigue damage separately. The CDM-based viscoplastic constitutive material model is implemented using a user-defined subroutine (UMAT). A standard specimen is used for carrying out uniaxial creep, fatigue, and creep–fatigue interaction tests to validate the material model. In addition, to further demonstrate the capability of the material model to predict the complex material behavior, a complex strain-control loading test is performed to validate the material model. The simulated and measured results are in good agreement at different temperatures and loadings, in particular for rapid cyclic softening behavior following crack initiation and propagation.

Creep-Fatigue Life Prediction of Stop and Regulating Valves on the Intermediate-Pressure Section of a 1000MW Steam Turbine

2013 ◽  
Author(s):  
Jianfeng Mao ◽  
Junhui Zhang ◽  
Weizhe Wang ◽  
Yingzheng Liu
Keyword(s):  
Fatigue Life ◽  
Steam Turbine ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Complex Stress ◽  
Fatigue Life Prediction ◽  
Temperature Fields ◽  
Intermediate Pressure ◽  
Creep Fatigue

The stop&regulating integrated valve on the intermediate-pressure (IP) section of a 1000MW steam turbine is presented in this paper. A multiaxial model based on continuum damage mechanics (CDM) is applied to life prediction of the valve. The transient stress and the temperature fields of the valve in a 1000MW supercritical steam turbine are investigated by using finite element method (FEM) for fatigue-creep. Since the turbine typically runs 120 days between starts, a simplified mission profile for a 120-day block was created. Accordingly, the 120-day loading block with plasticity and creep was run repetitively to achieve a 22 years creep-fatigue life prediction. The interaction between creep and fatigue was considered in total damage in proper order. Due to highly complex stress and structure, the multiaxial factors for fatigue and creep are assessed from the temporal and spatial points of view respectively. Furthermore, the creep-fatigue damage of the integrated valve is discussed in relation to the multiaxial factors. The results drawn from the multiaxial CDM model give a satisfactory life prediction on the valve.

A Continuum Damage Mechanics Model on Creep Rupture Life Assessment of a Steam Turbine Rotor

2005 ◽  
Vol 128 (1) ◽  
pp. 173-177 ◽  
Author(s):  
Jing JianPing ◽  
Meng Guang ◽  
Sun Yi ◽  
Xia SongBo
Keyword(s):  
Steam Turbine ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Turbine Rotor ◽  
Life Assessment ◽  
Continuum Damage ◽  
Creep Life ◽  
Steam Turbine Rotor ◽  
Mechanics Model ◽  
Nonlinear Continuum

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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