简介：Thevibrationproblemofapileofarbitrarysegmentswithvariablemodulusunderexcitingforceisestablished,inwhichtheinfluenceofthesoilunderpiletoeandthesurroundingsistakenintoaccount.WithLaplacetransforms,thetransmitfunctionsforvelocityanddisplacementofpilearederived.Furthermore,intermsoftheconvolutiontheoremandinversedLaplacetransform,ananalyticalsolutionforthetimedomainresponseofapilesubjectedtoasemi-sineimpulseisdeveloped,whichisthetheoreticalbasisofthesonicmethodinpileintegritytesting.Basedonthesolution,thevibrationpropertiesofpilewithsharporcontinuousmodulusarestudied.Thevalidityofthisapproachisverifiedthroughfidddynamictestsonsomeengineeringpiles.Itshowsthatthetheoreticalpredictionandtheresponseofthepileareingoodagreement.

简介：Basedonthecommercialcomputationalsoftware,athree-dimensionalfiniteelementmodeltosimulatethethermo-mechanicalbehaviorsinanuclearfuelrodisestablished;Bytakingintoconsiderationirradiation-swellingofthepelletandtheirradiationdamageeffectsinthecladdingtogetherwiththecouplingeffectsbetweenthetemperaturefieldandthemechanicalfield,theusersubroutinestodefinethespecialmaterialperformanceandboundaryconditionshavebeendevelopedindependentlyandvalidated.Three-dimensionalnumericalsimulationofthethermo-mechanicalcouplingbehaviorsinanuclearfuelrodiscarriedout,andtheevolutionrulesoftheimportantthermalandmechanicalvariablesareobtainedandanalyzed.Theresearchresultsindicatethat:(1)thefuelpelletswillbeincontactwiththecladdingathighburnup,whichwillinduceastrongmechanicalinteractionbetweenthem;(2)theirradiationcreepeffectplaysanimportantroleinthemechanicalbehaviorevolutioninthenuclearfuelrod.