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.

scholarly journals High Frequency Vibration Fatigue Behavior of Ti6Al4V Fabricated by Wire-Fed Electron Beam Additive Manufacturing Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-14 ◽  
Author(s):  
P. Wanjara ◽  
J. Gholipour ◽  
E. Watanabe ◽  
K. Watanabe ◽  
T. Sugino ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Gas Turbine ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Turbine Engine ◽  
Fatigue Data ◽  
The Impact

Following foreign object damage (FOD), a decision to repair components using novel additive manufacturing (AM) technologies has good potential to enable cost-effective and efficient solutions for aircraft gas turbine engine maintenance. To implement any new technology in the gas turbine remanufacturing world, the performance of the repair must be developed and understood through careful consideration of the impact of service life-limiting factors on the structural integrity of the component. In modern gas turbine engines, high cycle fatigue (HCF) is one of the greatest causes of component failure. However, conventional uniaxial fatigue data is inadequate in representing the predominant HCF failure mode of gas turbine components that is caused by vibration. In this study, the vibratory fatigue behavior of Ti6Al4V deposited using wire-fed electron beam additive manufacturing (EBAM) was examined with the motivation of developing an advanced repair solution for fatigue critical cold-section parts, such as blades and vanes, in gas turbine engine applications. High cycle fatigue data, generated using a combination of step-testing procedure and vibration (resonance) fatigue testing, was analyzed through Dixon–Mood statistics to calculate the endurance limits and standard deviations of the EBAM and wrought Ti6Al4V materials. Also plots of stress (S) against the number of cycles to failure (N) were obtained for both materials. The average fatigue endurance limit of the EBAM Ti6Al4V was determined to be greater than the wrought counterpart. But the lower limit (95% reliability) of 426 MPa for the EBAM Ti6Al4V was lower than the value of 497 MPa determined for wrought Ti6Al4V and was attributed to the slightly higher data scatter–as reflected by the higher standard deviation–of the former material.

Influence of Mission Variability on Fracture Risk of Gas Turbine Engine Components

2012 ◽  
Author(s):  
Michael P. Enright ◽  
Jonathan P. Moody ◽  
Ramesh Chandra ◽  
Alan C. Pentz
Keyword(s):  
Fracture Risk ◽  
Gas Turbine ◽  
Life Prediction ◽  
Damage Tolerance ◽  
Gas Turbine Engine ◽  
Fatigue Life Prediction ◽  
Turbine Engine ◽  
Risk Of Fracture ◽  
Failure Data ◽  
Engine Components

The need for application of probabilistic methods to fatigue life prediction of gas turbine engine components is being increasingly recognized by the U.S. Military. A physics-based probabilistic approach to risk assessment provides improved accuracy compared to a statistical assessment of failure data because it can be used to (1) predict future risk and (2) assess the influences of both deterministic and random variables that are not included in the failure data. Probabilistic risk and fatigue life prediction of gas turbine engine fracture critical components requires estimates of the applied stress and temperature values throughout the life of the component. These values are highly dependent upon the mission type and may vary from flight to flight within the same mission. Currently, standard missions are specified and used during the engine design process, but the associated stresses can differ significantly from stress values that are based on flight data recorder (FDR) information. For this reason, efforts are made to periodically update the standard missions and to assess the impact on component structural integrity and associated risk of fracture. In this paper, the influence of mission type and variability on fracture risk is illustrated for an actual gas turbine engine disk subjected to a number of different mission loadings. Disk stresses associated with each mission were obtained by scaling finite element model results based on RPM values obtained from engine flight recorder data. The variability in stress values throughout the life of the component was modeled using two different approaches to identify the upper and lower bound value influences on the risk of fracture. The remaining variables were based on default values provided in FAA Advisory Circular (AC) 33.14-1 “Damage Tolerance for High Energy Turbine Engine Rotors”. The risk of fracture was computed using a probabilistic damage tolerance computer code called DARWIN® (Design Assessment of Reliability With Inspection) and compared for each mission type to illustrate the maximum influence of mission type on fracture risk. The results can be used to gain insight regarding the influence of mission type and associated variability on the risk of fracture of realistic engine components.

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