The Reliability Estimation of the Low-Cycle Fatigue Life of Steam Turbine Rotors

1993 ◽  
Vol 207 (1) ◽  
pp. 49-53 ◽  
Author(s):  
S H Huang
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Steam Turbine ◽  
Dispersion Coefficient ◽  
Low Cycle Fatigue ◽  
Estimation Method ◽  
Reliability Estimation ◽  
Cycle Fatigue ◽  
Load Spectra ◽  
Turbine Rotors

In this paper, a technique to define the low-cycle fatigue life damage and its cumulative effects on steam turbine rotors using the reliability estimation method is presented. Because of the dispersion of external load spectra and the fatigue strength of materials, the dispersion coefficient is defined to describe the probability relationship between reliability and life damage. The definition of the dispersion coefficient differs according to the probability distribution of service life. The situation for both the logarithmic normal distribution and the Weibull distribution is analysed in this paper. Using this technique, the internal relationship between the crack initiation life damage and the crack propagation life damage is investigated under any selected reliability. It is helpful for managers of power stations to evaluate the state of turbines and to manage the service life of turbine rotors. This technique is useful in evaluating the residual fatigue life of rotors and determining the optimal detecting date. An example is presented in the paper and some valuable results are obtained.

scholarly journals Applicability of Notch Stress-Strain Correction Methods to Low-Cycle Fatigue Life Prediction of Turbine Rotors Subjected to Thermomechanical Loads

2018 ◽  
Vol 12 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Mariusz Banaszkiewicz ◽  
Waldemar Dudda
Keyword(s):  
Fatigue Life ◽  
Strain Amplitude ◽  
Upper Bound ◽  
Plastic Material ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Isothermal Conditions ◽  
Notch Stress ◽  
Turbine Rotors

Abstract The paper analyses the possibility of using analytical methods of notch stress-strain correction in low-cycle fatigue life predictions of steam turbine rotors operating under non-isothermal conditions. The assessment was performed by comparing strain amplitudes calculated using the Neuber and Glinka-Molski methods and those predicted by the finite element analysis (FEA) employing elastic-plastic material model. The results of investigations reveal that the Neuber method provides an upper bound limit, while the Glinka-Molski method results in a lower bound limit of strain amplitude. In the case of rotor heat grooves, both methods provide equally accurate results of notch strain amplitude and are suited to estimating lower and upper bound limits of low-cycle fatigue life under non-isothermal conditions.

Sign in / Sign up

Export Citation Format

Share Document