ICOPE-15-C035 Crack Propagation Life under Low Cycle Fatigue and High Cycle Fatigue of Nuclear Steam Turbine Rotors

In this study, the assessment and calculation methods for the crack propagation life of steam turbine rotor shafts containing defects are presented. The analytic methods for estimating the average stress and the alternating stress amplitude of the steam turbine rotor shafts are introduced. The defects on/in the rotor shafts were regularized by the method of fracture mechanics, and the high cycle fatigue crack propagation life and low cycle fatigue crack propagation life of the rotor shafts are estimated from Paris formula. Taking the 60MW turbine rotor shafts containing an initial surface defect and an initial internal defect as the examples respectively, the crack propagation life of them were calculated. The results indicated that the assessment method for the crack propagation life can preliminarily be both used to estimate the safety-operating life and to analyze the fracture reason of a steam turbine rotor shaft containing defects. This paper can provide reference for periodic maintenance and safety evaluation of turbine rotor shafts.

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LCF Initiated - HCF Propagated Crack Life Estimation of Gas Turbine Bolts

Volume 7A: Structures and Dynamics ◽

10.1115/gt2018-76968 ◽

2018 ◽

Author(s):

Amit K. Paspulati ◽

Krishna Veluru ◽

Kashinath Akki ◽

Rohit Khattar ◽

Sudeep Bosu ◽

...

Keyword(s):

Crack Propagation ◽

Gas Turbine ◽

High Cycle Fatigue ◽

Low Cycle Fatigue ◽

Evaluation Studies ◽

Three Dimensional ◽

Fatigue Loading ◽

Turbine Rotor ◽

Cycle Fatigue ◽

Compressor Rotor

This paper discusses the methodology to calculate high cycle fatigue (HCF) crack propagation life of gas turbine bolts and compares two dimensional (2D) HCF crack propagation life to three dimensional (3D) HCF crack propagation life. Gas turbine bolts when exposed to fatigue loading are prone to crack initiation and propagation (structural failure) during operation. In such cases cracks mostly are initiated by low cycle fatigue (LCF) and propagated by HCF. Therefore in current illustration the authors have evaluated crack propagation primarily initiated by low cycle fatigue and propagated by high cycle fatigue. 2D and 3D fracture methodology approaches had been used for analytical evaluation. The authors conclude on the efficacy of both the methods based on the data from the field. The coupling joint bolts located in the engine mid-section, which are used to join compressor rotor with turbine rotor are being considered for crack evaluation studies. The coupling bolts located in mid-section are primarily loaded by high axial bolt pre-loads needed to keep the joint intact, as well as loaded in bending due to rotor gravity sag. The crack propagation life is evaluated and validated with field data using cracked bolt specimen from the field.

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Superimposed Effect of High Cycle Fatigue and Low Cycle Fatigue Loadings on Small Crack Propagation Around Cooling Hole in A Directionally Solidified Ni-base Superalloy

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.68.129 ◽

2019 ◽

Vol 68 (2) ◽

pp. 129-135

Author(s):

Yuki YONAKUNI ◽

Shin YOSHIZAKI ◽

Masakazu OKAZAKI

Keyword(s):

Crack Propagation ◽

High Cycle Fatigue ◽

Low Cycle Fatigue ◽

Small Crack ◽

Cycle Fatigue ◽

Directionally Solidified ◽

Cooling Hole ◽

Base Superalloy ◽

Superimposed Effect

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

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1243/pime_proc_1993_207_006_02 ◽

1993 ◽

Vol 207 (1) ◽

pp. 49-53 ◽

Cited By ~ 2

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.

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