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1、AbstractInrecentpileultrasonictesting,itisaroutinetoconductatime-domainanalysisonthesignalsreceived.Importantparameterssuchassonictime,headwaveamplitude,dominantfrequencyandwaveformareusedtojudgetheintegrityofpiles.However,otherinformationlikespectralarenotwellexploited.Themajority
2、ofthedomesticandoversearesearchworksonultrasonicspectraarebasedontests.Thevalidityoftheresultsisstillunsubstantiatedduetothevariationoftestconditionsandtestmethods.Therefore,systematictheoreticalanalysesandnumericalsimulationareneededintheapplicationofultrasonicspectralanalysisinpi
3、letests.Inthisthesis,theANSYS/LS-DYNAisusedtoperformthenumericalsimulationinultrasonicfrequencydomain,andanemphasisisputonthefrequencydomaincharacteristicsofultrasonicwaves.Firstly,theselectionofultrasonicvibrationsourceisdiscussed,andthespectralcharacteristicsofvibrationsourcemani
4、pulatedbydifferentwindowfunctionareinvestigated.Byanalyzingthecharacteristicsofdifferentwindowfunction,thereasonablewindowfunctionsareselected.Andthewaytoreducespectralleakageandimprovetheresolutionoffrequencydomainisalsoinvestigated.Then,thepropagationofultrasonicwaveinthepileissi
5、mulatedusingLS-DYNA,andthepropagationlawofultrasonicwaveinconcretepileisanalyzed,andthepilevibrationlawisalsovalidatedbythecalculationofwavevelocity.Basedontheabovework,aspectralanalysisofsignalsreceivedatdifferenttransactionsofpileisconducted.Andthespectralinformationisdiscussed.A
6、detailedparametricstudyisgiventoinvestigatetheinfluenceoftransactiongeometry,testingmethod,testlocation,testdistanceanddefectontheresults,andthecorrespondentlawsaresummarized.Finally,thenumericalresultsareverifiedbythesitetestresults,andcorrespondentsuggestionsofpracticalultrasonic
7、testingarealsogiven.Theapplicationofultrasonicfrequencydomainanalysisinpiletestisanalyzedindetail,andtheresultisofcertainapplicationandpopularizationsignificance.Keywords:frequencydomainanalysispiletestingfrequencydomaincharacteristicsultrasonicvibrationsourcesimulationanalysisin目录
8、摘要(I)Abstract(II)1绪论(1)1.1
