Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722393229
Category :
Languages : en
Pages : 58
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Book Description
The results of an investigation are described for fatigue reliability in engine structures. The description consists of two parts. Part 1 is for method development. Part 2 is a specific case study. In Part 1, the essential concepts and practical approaches to damage tolerance design in the gas turbine industry are summarized. These have evolved over the years in response to flight safety certification requirements. The effect of Non-Destructive Evaluation (NDE) methods on these methods is also reviewed. Assessment methods based on probabilistic fracture mechanics, with regard to both crack initiation and crack growth, are outlined. Limit state modeling techniques from structural reliability theory are shown to be appropriate for application to this problem, for both individual failure mode and system-level assessment. In Part 2, the results of a case study for the high pressure turbine of a turboprop engine are described. The response surface approach is used to construct a fatigue performance function. This performance function is used with the First Order Reliability Method (FORM) to determine the probability of failure and the sensitivity of the fatigue life to the engine parameters for the first stage disk rim of the two stage turbine. A hybrid combination of regression and Monte Carlo simulation is to use incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system fatigue life to the engine parameters of the high pressure turbine. 'ne variation in the primary hot gas and secondary cooling air, the uncertainty of the complex mission loading, and the scatter in the material data are considered. Cruse, Thomas A. and Mahadevan, Sankaran and Tryon, Robert G. Glenn Research Center...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 62
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Book Description
Author: Leonid Borisovich Getsov
Publisher: Springer Nature
ISBN: 9811605343
Category : Science
Languages : en
Pages : 469
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Book Description
This book discusses several mechanical and material problems that are typical for gas turbine components. It discusses accelerated tests and other methods for increasing the reliability of gas turbine engines. Special attention is given to non-traditional methods for calculating the strength characteristics and longevity of the main components. This first volume focuses on the selection of materials, deformation and destruction mechanisms in connection with stationary and non-stationary loading, and types of material damage such as the thermal fatigue. Particular attention is paid to the issues of the properties of single crystal alloys, the relationship between structure and properties, the influence of technological factors and long-term operation. The characteristics of creep resistance, crack resistance, and resistance to cyclic deformation of different alloys are given.
Author: North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development
Publisher:
ISBN: 9789283610311
Category : Aeronautics
Languages : en
Pages :
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Book Description
Author: Niranjan Sarangi
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 11
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Book Description
Structural analysis of annular combustors of aero gas turbines presents substantial challenges to engine-development establishments because of its multifunctional aspects such as complex geometry, thin wall structures, and stringent airworthiness requirements. This paper outlines an experimental methodology for fatigue life evaluation of an annular combustor casing using a closed-loop hydraulic test facility and presents results corresponding to the initial configuration. Premature fatigue failure has revealed that a design feature with a high stress concentration on the combustor casing needs to be modified. Iterative studies are taken up to overcome the design deficiency. This paper presents a unique approach whereby the experimental results for a full-scale annular combustor are correlated with numerical predictions for ensuring structural integrity in accordance with military airworthiness standards.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
Author: Efstratios Nikolaidis
Publisher: CRC Press
ISBN: 0203483936
Category : Mathematics
Languages : en
Pages : 1216
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Book Description
Researchers in the engineering industry and academia are making important advances on reliability-based design and modeling of uncertainty when data is limited. Non deterministic approaches have enabled industries to save billions by reducing design and warranty costs and by improving quality. Considering the lack of comprehensive and defini
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723748509
Category : Science
Languages : en
Pages : 32
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Book Description
Two series of low cycle fatigue (LCF) test data for two groups of different aircraft gas turbine engine compressor disk geometries were reanalyzed and compared using Weibull statistics. Both groups of disks were manufactured from titanium (Ti-6Al-4V) alloy. A NASA Glenn Research Center developed probabilistic computer code Probable Cause was used to predict disk life and reliability. A material-life factor A was determined for titanium (Ti-6Al-4V) alloy based upon fatigue disk data and successfully applied to predict the life of the disks as a function of speed. A comparison was made with the currently used life prediction method based upon crack growth rate. Applying an endurance limit to the computer code did not significantly affect the predicted lives under engine operating conditions. Failure location prediction correlates with those experimentally observed in the LCF tests. A reasonable correlation was obtained between the predicted disk lives using the Probable Cause code and a modified crack growth method for life prediction. Both methods slightly overpredict life for one disk group and significantly under predict it for the other.Melis, Matthew E. and Zaretsky, Erwin V. and August, RichardGlenn Research CenterAIRCRAFT ENGINES; GAS TURBINE ENGINES; PROBABILITY THEORY; RELIABILITY; FAILURE ANALYSIS; LIFE (DURABILITY); FATIGUE TESTS; WEIBULL DENSITY FUNCTIONS; PREDICTION ANALYSIS TECHNIQUES; STRESS ANALYSIS; THERMAL STRESSES; TEMPERATURE EFFECTS; RESIDUAL STRESS; CRACK PROPAGATION; COMPUTER PROGRAMS; ALUMINUM ALLOYS; TITANIUM ALLOYS; VANADIUM ALLOYS
Author: D. A. Hull
Publisher:
ISBN:
Category :
Languages : en
Pages : 37
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Book Description
Author: HR. Millwater
Publisher:
ISBN:
Category : Damage tolerance
Languages : en
Pages : 17
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Book Description
An enhanced life management process based on probabilistic damage tolerance methods has been developed to address material anomalies in titanium rotating components of gas turbine engines. Related methods are being used as tools to investigate the impact of engine monitoring and usage variability on prognosis for field readiness and life management. This paper begins with an overview of the process of probabilistic damage tolerant design, using the DARWIN® computer program to illustrate the interplay between various random variables and the conventional elements of structural design and life prediction. Special attention is then given to the initial distribution of material anomalies, scatter in fatigue crack growth data, and variability in complex mission histories. The significance of each source of variability for different applications is discussed.
