scholarly journals THE EFFECT OF NOTCHES ON THE FATIGUE LIFE OF A NICKEL-BASE GAS TURBINE DISK MATERIAL

2018 ◽  
Vol 20 ◽  
pp. 34-42 ◽  
Author(s):  
Robert Eriksson ◽  
Johan Moverare ◽  
Zhe Chen ◽  
Kjell Simonsson
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Low Cycle Fatigue ◽  
Notch Root ◽  
Strain Range ◽  
Compact Tension ◽  
Critical Distance ◽  
Cycle Fatigue ◽  
Plastic Strain Range ◽  
Life Model

Gas turbine disks carry significant load under high temperatures and may be subject to fatigue failure. Disks contain several notches in the form of the fir tree blade attachments. Low cycle fatigue tests were performed on blunt notch compact tension specimens made from alloy 718. The results indicated that notch support needed to be incorporated not to cause an overly conservative life prediction. The notch support diminished as the plastic strain range decreased, indicating that notch support is only present in the low cycle fatigue regime. A critical distance approach was applied to account for the notch support. An equation relating the critical distance to the notch root stress was derived. The chosen life model was formulated in terms of a variation on the Smith–Watson–Topper (SWT) parameter. The modified SWT parameter taken at the critical distance was used in a life model calibrated for smooth specimens to successfully predict the fatigue life of notched specimens.

Low Cycle Fatigue Life Model for Gas Turbine Engine Disks

1980 ◽  
Vol 102 (1) ◽  
pp. 45-49
Author(s):  
T. G. Meyer ◽  
T. A. Cruse
Keyword(s):  
Gas Turbine ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Strain Range ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine ◽  
Mission History ◽  
Life Model ◽  
Temperature Exposure

A low cycle fatigue (LCF) life exhaustion method is developed for gas turbine engine disks subjected to complex mission history loading. The method is incorporated into an algorithm for LCF life exhaustion prediction as a function of component, material, mission history, and mission ordering. Principal features in the LCF life model include a simple strain range-mean stress correlation model, a predictive model for the effects of strain-hardened surface layers due to machining and the effects of dwell (creep) due to elevated temperature exposure time, a fracture mechanics-based nonlinear, cumulative damage model, and full-scale component verification.

scholarly journals The Attempt of the Low-Cycle Fatigue Life Description of Chosen Creep-Resistant Steels Under Mechanical and Thermal Interactions

2017 ◽  
Vol 62 (4) ◽  
pp. 2349-2353
Author(s):  
J. Okrajni ◽  
A. Marek
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Plastic Strain Range ◽  
Mechanical Fatigue ◽  
Versus Parameter ◽  
Creep Resistant Steels

AbstractThe study focuses on the problem of determination of low-cycle fatigue properties for the chosen group of creep-resistant steels used in the power and chemical industries. It tries to find the parameter which would describe well the fatigue life and take into account mechanical loads and temperature. The results of LCF tests have been presented in the paper. New parameter P has been introduced. This parameter joins a plastic strain range, a stress range and temperature. The fatigue life has been predicted versus parameter P. The comparison of the predicted and observed values of fatigue life shows the agreement between these values. The method of fatigue life prediction formulated in this way is expected to describe the behavior of materials under thermo-mechanical fatigue.

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2020 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. at 400°C and 600°C, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner’s rule on the stored plastic strain energy basis.

Low-Cycle Fatigue Life of Continuously Cyclic-Hardening Material

2021 ◽  
Author(s):  
Zhong Zhang ◽  
Xijia Wu
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Root Mean Square ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Mean Square ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Hardening Material ◽  
Plastic Strain Range

Abstract A general fatigue life equation is derived by modifying the Tanaka-Mura-Wu dislocation pile-up model for variable strain-amplitude fatigue processes, where the fatigue crack nucleation life is expressed in terms of the root mean square of plastic strain range. Low-cycle fatigue tests were conducted on an austenitic stainless steel. At 400 ? and 600 ?, the material exhibits continuously cyclic-hardening behaviour. The root mean square of plastic strain ranges is evaluated from the experimental data for each test condition at strain rates ranging from 0.0002/s to 0.02/s. The variable-amplitude Tanaka-Mura-Wu model is found to be in good agreement with the LCF data, which effectively proves Miner's rule on the stored plastic strain energy basis.

Multiaxial Low Cycle Fatigue Life Prediction at 300 °C Using Equivalent Strain Appoach

2011 ◽  
Vol 361-363 ◽  
pp. 1669-1672
Author(s):  
Wen Xiao Zhang ◽  
Guo Dong Gao ◽  
Guang Yu Mu
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Range ◽  
Cyclic Fatigue ◽  
Equivalent Strain ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue

The low cycle fatigue behavior was experimentally studied with the 3-dimension notched LD8 aluminum alloy specimens at 300°C. The 3- dimension stress-strain responses of specimens were calculated by means of the program ADINA. The multiaxial fatigue life prediction was carried out according to von Mises’s equivalent theory. The results from the prediction showed that the equivalent strain range can be served as the valid mechanics for predicting multiaxial high temperature and low cyclic fatigue life.

Assessment of low-cycle fatigue life of Sn-3.5mass%Ag-X (X=Bi or Cu) alloy by strain range partitioning approach

2001 ◽  
Vol 30 (9) ◽  
pp. 1184-1189 ◽  
Author(s):  
Yoshiharu Kariya ◽  
Tomoo Morihata ◽  
Eisaku Hazawa ◽  
Masahisa Otsuka
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cycle Fatigue ◽  
Cu Alloy
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