NewstressintensityfactorsolutionsforanellipticalcrackinaplateOriginalResearchArticle

Crackassessmentinengineeringstructuresreliesfirstonaccurateevaluationofthestressintensityfactors.Inrecentyears,alargeworkwasconductedinFrancebytheAtomicEnergyCommissiontodevelopinfluencecoefficientsforsurfacecracksinpipes.However,theproblemofembeddedcracksinplates(andpipes),whichisalsoofpracticalimportance,hasnotreceivedsomuchattention.Presently,solutionsforellipticalcracksareavailableeitherininfinitesolidwithapolynomialdistributionofnormalloadingorinplate,butrestrictedtoconstantorlinearlyvaryingtension. ThispaperpresentstheworkconductedatEDFR&Dtoobtaininfluencecoefficientsforplatescontaininganellipticalcrackwithawiderangeoftheparameters:relativesize(2a/tratio),shape(a/cratio)andfreesurfaceproximity(a/dratio,wheredisthedistancefromthecenteroftheellipsetotheclosestfreesurface).Thesecoefficientsweredevelopedthroughextensive3Dfiniteelementcalculations:200geometricalconfigurationsweremodeled,eachcontainingfrom18,000to26,000nodes.Thelimitingcaseofthetunnelcrack(a/c=0)wasalsoanalyzedwith2Dfiniteelementcalculation(50geometricalconfigurations).Theaccuracyoftheresultswascheckedbycomparisonwithanalyticalsolutionsforinfinitesolidsand,whenpossible,withsolutionsforfinite-thicknessplates(generallyloadedinconstanttension). ThesesolutionshavebeenintroducedintheRSE-MCodethatprovidesrulesandrequirementsforin-serviceinspectionofFrenchPWRcomponents.