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多模Lamb波信号时反过程频散补偿分析.docx

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多模Lamb波信号时反过程频散补偿分析 Abstract Lambwavesareatypeofultrasonicwavesthatpropagatethroughplatesorthin-walledstructures.However,thedispersionphenomenoncangreatlyaffectthequalityofLambwavesignals,especiallyinmulti-modeLambwavesignals.Inthispaper,weanalyzethedispersioncompensationforLambwavesignalsinthereverseprocessfrequencydomain.WeproposeacompensationmethodbasedontheinverseFouriertransformandthesingularvaluedecomposition.Thecompensationmethodisverifiedwithnumericalsimulations.OurresultsshowthattheproposedmethodcaneffectivelyeliminatethefrequencydispersiondistortionandimprovetheaccuracyofLambwavesignals. 1.Introduction Lambwaveshavebeenwidelyusedforstructuralhealthmonitoring(SHM)ofthin-walledstructures,suchaspipelines,aircraftwings,andpressurevessels.Comparedwithotherultrasonicwaves,Lambwaveshavetheadvantageofpropagatinglongdistanceswithlimitedattenuationandprovidinginformationabouttheoverallhealthofthestructure.However,Lambwavesalsohaveadispersionproperty,whichcausesthewavevelocitytochangewithfrequency.ThisdispersionphenomenoncanaffectthequalityofLambwavesignals,especiallyinmulti-modeLambwavesignals. ThedispersionofLambwavescanbemodeledusingadispersionequationderivedfromthewaveequationandtheboundaryconditionsoftheplateorstructure.ThedispersionequationshowsthatthephasevelocityofLambwavesdependsonthefrequencyandthewavenumber,whichdeterminesthemodeofLambwaves.Thedispersionphenomenonleadstothefrequency-dependentphaselagandattenuationofdifferentLambwavemodes,whichcancausethedistortionofLambwavesignals. SeveralmethodshavebeenproposedtocompensateforthedispersionofLambwavessignals.Thesemethodscanbedividedintotwocategories:time-domaincompensationandfrequency-domaincompensation.Thetime-domaincompensationmethodisbasedonthetime-reversalprinciple,whichcancompensateforthedispersionbyreversingthetime-domainsignal.However,thismethodrequirespreciseknowledgeofthedispersionpropertiesandthegeometryofthestructure,whichmaynotbeavailableinpracticalapplications.Thefrequency-domaincompensationmet