Fracture mechanics LCF life prediction system with application to anadvanced gas turbine alloy

1975 ◽  
Author(s):  
J. HURCHALLA ◽  
H. JOHNSON ◽  
R. WALLACE
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
Prediction System

Damage Tolerance Based Life Prediction in Gas Turbine Engine Blades Under Vibratory High Cycle Fatigue

1997 ◽  
Vol 119 (1) ◽  
pp. 143-146 ◽  
Author(s):  
D. P. Walls ◽  
R. E. deLaneuville ◽  
S. E. Cunningham
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine ◽  
Aspect Ratios

A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a nonresonant mode, with one blade subjected to only the nonresonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution, which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

scholarly journals Damage Tolerance Based Life Prediction in Gas Turbine Engine Blades Under Vibratory High Cycle Fatigue

1995 ◽  
Author(s):  
David P. Walls ◽  
Robert E. deLaneuville ◽  
Susan E. Cunningham
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Resonant Mode ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine

A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a non-resonant mode, with one blade subjected to only the non-resonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

Crack Propagation in Gas Turbine Rotor Disks: Comparison of Experimental Results at Real Components With Fatigue Life Prediction

2001 ◽  
Author(s):  
E. Maldfeld ◽  
M. Schödel ◽  
C. Berger
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Life Prediction ◽  
Turbine Rotor ◽  
Machined Surface ◽  
Crack Growth Behaviour ◽  
Rotor Disk ◽  
Stress Criteria

Rotor disks of gas turbines are high stressed components and for safe life design both stress criteria and fracture mechanics are needed. Due to the forging process in rotor disks flaws have to be considered. There exists a certain detection limit, beneath no flaw size is detectable. A comparison of predicted and observed crack propagation in a real gas turbine rotor disk with machined surface cracks is presented. The comparision of experimental crack growth behaviour and life prediction shows that the fracture mechanics analysis is conservative and that non detectable flaws within gas turbine rotor components cannot hurt safe service operation.

Equivalent Initial Flaw Size Distribution Determination for Gas Turbine Blades Based Upon Inspection Data

2005 ◽  
Author(s):  
W. S. Johnson ◽  
A. C. Wilson ◽  
S. Highsmith
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbine ◽  
Life Prediction ◽  
Turbine Blades ◽  
Flaw Size ◽  
Fatigue Life Prediction ◽  
Gas Turbine Blades ◽  
Critical Components ◽  
Inspection Data ◽  
Industrial Gas Turbine

A fracture mechanics-based methodology is presented for determining equivalent initial flaw size (EIFS) distributions from field inspection data accounting for different service histories of fracture critical components. The EIFS distribution based on inspection data from a subset of the fleet allows for an assessment of initial material/manufacturing quality and enables a probabilistic fracture mechanics-based fatigue life prediction for the fleet as a whole. The methodology is demonstrated on an industrial gas turbine blade experiencing in-service cracking.

Life Prediction Method of CC and DS Ni Base Superalloys Under High Temperature Biaxial Fatigue Loading

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
Takashi Ogata
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Life Prediction ◽  
Compressive Strain ◽  
Prediction Method ◽  
Strain Range ◽  
Fatigue Loading ◽  
Normal Strain ◽  
Biaxial Fatigue

Polycrystalline conventional casting (CC) and directionally solidified (DS) Ni base superalloys are widely used as gas turbine blade materials. It was reported that the surface of a gas turbine blade is subjected to a biaxial tensile-compressive fatigue loading during a start-stop operation, based on finite element stress analysis results. It is necessary to establish the life prediction method of these superalloys under biaxial fatigue loading for reliable operations. In this study, the in-plane biaxial fatigue tests with different phases of x and y directional strain cycles were conducted on both CC and DS Ni base superalloys (IN738LC and GTD111DS) at high temperatures. The strain ratio ϕ was defined as the ratio between the x and y directional strains at 1/4 cycle and was varied from 1 to −1. In ϕ=1 and −1. The main cracks propagated in both the x and y directions in the CC superalloy. On the other hand, the main cracks of the DS superalloy propagated only in the x direction, indicating that the failure resistance in the solidified direction is weaker than that in the direction normal to the solidified direction. Although the biaxial fatigue life of the CC superalloy was correlated with the conventional Mises equivalent strain range, that of the DS superalloy depended on ϕ. The new biaxial fatigue life criterion, equivalent normal strain range for the DS superalloy was derived from the iso-fatigue life curve on a principal strain plane defined in this study. Fatigue life of the DS superalloy was correlated with the equivalent normal strain range. Fatigue life of the DS superalloy under equibiaxial fatigue loading was significantly reduced by introducing compressive strain hold dwell. Life prediction under equibiaxial fatigue loading with the compressive strain hold was successfully made by the nonlinear damage accumulation model. This suggests that the proposed method can be applied to life prediction of the gas turbine DS blades, which are subjected to biaxial fatigue loading during operation.

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