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Predicting Lifetime of a Thermomechanically Loaded ComponentNASALIFE is a computer program for predicting the lifetime, as affected by low cycle fatigue (LCF) and creep rupture, of a structural component subject to temporally varying, multiaxial thermomechanical loads. The component could be, for example, part of an aircraft turbine engine. Empirical data from LCF tests, creep rupture tests, and static tensile tests are used as references for predicting the number of missions the component can withstand under a given thermomechanical loading condition. The user prepares an input file containing the creep-rupture and cyclic-fatigue information, temperature-dependent material properties, and mission loading and control flags. The creep rupture information can be entered in tabular form as stress versus life or by means of parameters of the Larson-Miller equation. The program uses the Walker mean-stress model to adjust predicted life for ranges of the ratio between the maximum and minimum stresses. Data representing complex load cycles are reduced by the rainflow counting method. Miner's rule is utilized to combine the damage at different load levels. Finally, the program determines the total damage due to creep and combines it with the fatigue damage due to the cyclic loading and predicts the approximate number of missions a component can endure before failing.
Document ID
20110013627
Document Type
Other - NASA Tech Brief
Authors
Murthy, Pappu L. N.
(NASA Glenn Research Center Cleveland, OH, United States)
Gyekenyesi, John Z.
(N and R Engineering and Management Services Parma Heights, OH, United States)
Mital, Subodh
(Toledo Univ. OH, United States)
Brewer, David N.
(Army Aviation Systems Command Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
December 1, 2006
Publication Information
Publication: NASA Tech Briefs, December 2006
Subject Category
Man/System Technology And Life Support
Report/Patent Number
LEW-18081
Distribution Limits
Public
Copyright
Public Use Permitted.
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