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Equivalent damage: A critical assessmentConcepts in equivalent damage were evaluated to determine their applicability to the life prediction of hot path components of aircraft gas turbine engines. Equivalent damage was defined as being those effects which influence the crack initiation life-time beyond the damage that is measured in uniaxial, fully-reversed sinusoidal and isothermal experiments at low homologous temperatures. Three areas of equivalent damage were examined: mean stress, cumulative damage, and multiaxiality. For each area, a literature survey was conducted to aid in selecting the most appropriate theories. Where possible, data correlations were also used in the evaluation process. A set of criteria was developed for ranking the theories in each equivalent damage regime. These criteria considered aspects of engine utilization as well as the theoretical basis and correlative ability of each theory. In addition, consideration was given to the complex nature of the loading cycle at fatigue critical locations of hot path components; this loading includes non-proportional multiaxial stressing, combined temperature and strain fluctuations, and general creep-fatigue interactions. Through applications of selected equivalent damage theories to some suitable data sets it was found that there is insufficient data to allow specific recommendations of preferred theories for general applications. A series of experiments and areas of further investigations were identified.
Document ID
19830009271
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Laflen, J. R.
(General Electric Co. Cincinnati, OH, United States)
Cook, T. S.
(General Electric Co. Cincinnati, OH, United States)
Date Acquired
September 4, 2013
Publication Date
November 1, 1982
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
R82AEG533
NAS 1.26:167874
NASA-CR-167874
Accession Number
83N17542
Funding Number(s)
PROJECT: RTOP 505-33-22
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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