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dc.contributor.authorHolland, Chase Carltonen_US
dc.date.accessioned2014-03-14T21:31:02Z
dc.date.available2014-03-14T21:31:02Z
dc.date.issued2012-02-20en_US
dc.identifier.otheretd-03052012-023245en_US
dc.identifier.urihttp://hdl.handle.net/10919/41436
dc.description.abstractIn American rail operations, rails fail due to the combined effects of rail wear due to repetitive wheel contact and the growth of surface and sub-surface cracks and flaws. Rail maintenance includes frequent uncoupled wear and ultrasonic inspections that determine the amount of wear that the rail has undergone and the presence of cracks and flaws. A rail is removed from service when its wear reaches a pre-determined wear limit or a flaw is detected in its cross section. In rail research, the life of a rail is typically estimated using fracture mechanic or fatigue methods and an assumed flaw geometry. Multiple models ranging from complex elastic-plastic finite element models to simplified representations of a beam on an elastic foundation have been developed to predict the life of a rail. The majority of rail failure models do not incorporate rail wear into their analysis, and assume an unworn rail geometry. In order to account for rail wear, certain models adopt simplified rail geometries that uncouple rail wear into top-wear and side-wear. This thesis presents a rail failure model that describes the combined effects of rail wear and crack growth through the development of a functional relationship between input variables describing the geometry, loading, and material properties of a given rail and output variables describing the life characteristics of the rail. This relationship takes the form of multiple response surfaces estimating the desired output variables. Finite element models incorporating worn rail profiles and an assumed crack geometry corresponding to a detail fracture are combined to determine the state of stress and strain at the assumed flaw. Strain-life fatigue methods and fracture mechanic concepts are used to develop the output variables necessary to describe the life of the rail using the finite element model results. The goals of this research are to predict the remaining fatigue life and estimate the crack-growth rate of the rail based on the minimum number of geometry, loading, and material property independent variables. The outputs developed to describe the railâ s remaining life are intended to be used for the decision making for rail removal.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartHolland_CC_T_2012.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectrailroad tracken_US
dc.subjectdetail fractureen_US
dc.subjectresponse surfaceen_US
dc.subjectfractureen_US
dc.subjectfatigueen_US
dc.subjectFinite element analysisen_US
dc.titleComputational Methods for Estimating Rail Lifeen_US
dc.typeThesisen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMechanical Engineeringen_US
dc.contributor.committeechairWest, Robert L. Jr.en_US
dc.contributor.committeememberAhmadian, Mehdien_US
dc.contributor.committeememberDowling, Norman E.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03052012-023245/en_US
dc.date.sdate2012-03-05en_US
dc.date.rdate2012-03-19
dc.date.adate2012-03-19en_US


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