Probabilistic modeling and simulation of metal fatigue life prediction

dc.contributor.advisorKolar, Ramesh
dc.contributor.advisorWood, E. Roberts
dc.contributor.authorHeffern, Thomas V.
dc.contributor.departmentAeronautics and Astronautics
dc.dateSeptember 2002
dc.description.abstractThe work of this thesis was to investigate the probability distributions of test data taken for aluminum 7050-T7451, and to attempt to develop a probability based model from the variation of the 4 fatigue life constants ( , f ̤, ' f ,Ì b,c). The goal was to create strain-life-probability curves that would more accurately describe the likelihood of failure at a given strain amplitude. The investigator determined that the test data did not demonstrate any consistent known probability density function. The investigator cautioned against assuming a normal distribution before it could be completely established as the predominate probability density function. Possible consequences of invalid assumptions were presented. Attempts were made to explain the disparity of sample data between two different laboratories testing of the same material. Assuming random behavior within an established range, probability based models were developed using the 4 strain- life constants. It was determined that in order to create a complete probability based model, an accurate regression of the test data must fit all strain levels to include the intermediate strain level's "knee". In an attempt to solve that problem, 8 parameter equations were explored. Methods to predict the 8 parameters included random number simulation combined with non- least squares curve fits, evolutionary algorithms and genetic algorithms.en_US
dc.description.distributionstatementApproved for public release; distribution is unlimited.
dc.description.serviceMajor, United States Marine Corps .en_US
dc.format.extentxviii, 116 p. : ill. (some col.)en_US
dc.publisherMonterey, California. Naval Postgraduate Schoolen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.en_US
dc.subject.authorMetal fatigueen_US
dc.subject.authorVariable strain-lifeen_US
dc.subject.authorMonte Carlo simulationen_US
dc.subject.authorService life extensionen_US
dc.subject.authorEvolutionary algorithmsen_US
dc.subject.authorGenetic algorithmsen_US
dc.subject.authorAluminum 7050-T7451en_US
dc.subject.authorProbabilistic investigationen_US
dc.subject.lcshStrain hardeningen_US
dc.titleProbabilistic modeling and simulation of metal fatigue life predictionen_US
etd.thesisdegree.disciplineAeronautical Engineeringen_US
etd.thesisdegree.grantorNaval Postgraduate Schoolen_US
etd.thesisdegree.nameM.S. in Aeronautical Engineeringen_US
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