简介:Asolutionispresentedforaclassoftwo-dimensionalelectroelasticbranchedcrackproblems.ExplicitGreen’sfunctionforaninterfacecracksubjecttoanedgedislocationisdevelopedusingtheextendedStrohformulationallowingthebranchedcrackproblemtobeexpressedintermsofcoupledsingularintegralequations.Theintegralequationsareobtainedbythemethodthatmodelsakinkasacontinuousdistributionofedgedislocations,andthedislocationdensityfunctionisdefinedonthelineofthebranchcrackonly.Competitionbetweencrackextensionalongtheinterfaceandkinkingintothesubstrateisinvestigatedusingtheintegralequationsandthemaximumenergyreleaseratecriterion.Numericalresultsarepresentedtoshowtheeffectofelectricfieldonthepathofcrackextension.
简介:Thispaperdealswiththeelectro-elasticcouplinginteractionbetweenapiezoelectricscrewdislocationwhichislocatedinsidetheellipticalinhomogeneityandanelectricallyconductiveconfocalrigidlineunderremoteanti-planeshearstressesandin-planeelectricalloadsinpiezoelectriccompositematerial.Theanalytical-functionsofthecomplexpotentials,stressfieldsandtheimageforceactingonthepiezoelectricscrewdislocationareobtainedbasedontheprincipleofconformalmapping,themet...
简介:Mechanicalandelectricaldamagesareintroducedtostudythefracturemechanicsofpiezoelectricceramicsinthispaper.Twokindsofpiezoelectricfracturecriteriaareestablishedusingthemethodofleastsquarescombinedwithadamageanalysisofthewell-knownpiezoelectricfractureexperimentsofParkandSun's.Oneisbasedonalinearcombinationofthemechanicalandelectricaldamagesandtheotherontheirnonlinearcombination.WhenthecombineddamageDisuptoitscriticalvalueDc,piezoelectricfractureoccurs.Itisfoundfromthequalitativecomparisonofthenumericalresultswiththeexperimentaldatathatthenonlinearlycombineddamagefracturecriterioncangiveabetterpredictionofpiezoelectricfracture.Anditisconcludedfromthenonlinearlycombineddamagefracturecriterionthatanegativeelectricfieldimpedesfracturewhereastheeffectofapositiveelectricfieldonfracturedependsonitsmagnitude.
简介:Wereportthefabricationprocessofpiezoelectriccellulosepaperandtheenhancementmethodofitspiezoelectricproperty.Stretchingmethodwithdifferentwet-drawingratioswasintroducedtoincreasethepiezoelectricpropertyofcellulosepaperduringregenerationprocess.ItisobservedthattheYoung’smodulusandthepiezoelectricchargeconstantsareverydependentonthedrawingratioandthedirectionofnanofibrilsofpiezoelectricpaper.Usingtheenhancedpiezoelectricproperty,weprovethattheflexibleregeneratedpiezoelectriccellulosecanbeappliedtothepotentialacousticapplicationssuchasthinpiezoelectricpaperspeaker.
简介:Thecoupledelasticandelectricfieldsforanisotropicpiezoelectricmaterialswithelectri-callypermeablecracksareanalyzedbyusingStrohformulainanisotropicelasticity.ItisshownfromthesolutionthatthetangentcomponentoftheelectricfieldstrengthandthenormalcomponentoftheelectricdisplacementalongthefacesofcracksareaUconstants,andtheelectricfieldintensityandelec-tricdisplacementhavethesingularityoftype(1/2)atthecracktip.Theenergyreleaserateforcrackpropagationdependsonboththestressintensityfactorandmaterialconstants.Theelectricfieldinten-sityandelectricdisplacementinsideelectricallypermeablecracksareallconstants.
简介:Thispapergivesanexactanalysisofarotatingpiezoelectricsphericalshellwitharbitrarythickness.Atfirst,threedisplacementfunctionsareintroducedtosimplifythebasicequationsofasphericallyisotropic,piezoelectricmedium.Byexpandingthedisplacementfunctionsaswellastheelectricpotentialintermsofsphericalharmonics,thebasicequationsofequilibriumareconvertedtoanuncoupledEulertype,secondorderordinarydifferentialequationandacoupledsystemofthreesecondorderordinarydifferentialequations.Ageneralsolutiontothehomogeneousequationsofequilibriumisthenderived.Thestaticanalysisofarotatingsphericalshellisthenperformedandnumericalexampleispresented.
简介:Thispaperpresentsthevibrationssuppressionofathermoelasticbeamsubjecttosuddenheatinputbyasinglepiezoelectricactuator.Anoptimizationproblemisformulatedastheminimizationofaquadraticfunctionalintermsofdisplacementandvelocityatagiventimeandwiththeleastcontroleffort.Thesolutionmethodisbasedonacombinationofmodalexpansionandvariationalapproaches.Themodalexpansionapproachisusedtoconverttheoptimalcontrolofdistributedparametersystemintotheoptimalcontroloflumpedparametersystem.Byutilizingthevariationalapproach,anexplicitoptimalcontrollawisderivedandthedeterminationofthecorrespondingdisplacementandvelocityisreducedtosolvingasetofordinarydifferentialequations.Numericalresultsarepresentedtodemonstratetheeffectivenessandtheapplicabilityoftheproposedmethod.
简介:Anoptimizedtransducerprototypewithasandwichstructurevibratedlongitudinallyisproposedforatransmitterinacousticlogging,especiallyinacousticloggingwhiledrilling,bytakingaccountofdrillingenvironmentswithhightemperatureandpressure,aswellasstrongcollardrillingvibrationduringthedrillingprocess.Aimedtoimprovethetransmittingperformance,numericalandexperimentalstudiesforthetransduceroptimizationareconducted.Theimpactoflocationandlengthofthepiezoelectricstackonresonancecharacteristicsandeffectiveelectromechanicalcouplingcoefficientiscalculatedandanalyzed.Admittanceandtransmittingperformanceoftheproposedtransduceraremeasuredinlaboratoryexperiments,andtheresultsarecomparedwithsimulatedones.Itisshownthatthenewlyproposedtransducerhashighertransmittingperformancewithlowerresonancefrequencies.Thisworkprovidestheoreticalandexperimentalbasesfortransducerdesigningandacousticwavemeasurementsinacousticlogging,especiallyinacousticloggingwhiledrilling.
简介:Thispaperisconcernedwiththeoptimumdesignandsensitivityanalysismethodsofpiezo-electricintelligenttrussesonthestructuralstiffnessandfree-vibrationfrequency.Onthebasisofthefiniteel-ementmethodandtakingintoaccountthemechanical-electriccouplingeffectunderelectricloadandme-chanicalload,thecomputationalformulaofsensitivitiesofstructuraldisplacementandfree-vibrationfrequen-cywithrespecttothesizeandshapedesignvariablesareproposed.Anewkindofdesignvariableoftheelectricvoltageandthecalculatingmethodofdisplacementsensitivitywithrespecttotheelectricvoltagevari-ableispresented.Thenewmethodforstructuraldeformationcontrolbyoptimizingthevoltagesofpiezoelec-tricactivebarsisgiven.ThenumericalmethodsofoptimumdesignandsensitivityanalysisforpiezoelectrictrussstructuresareimplementedinJIFEXsoftware.Numericalexamplesdemonstratetheeffectivenessofthemethodsandtheprogram.
简介:Afinitedifference/boundaryintegralproceduretodeterminetheacousticreflectedpressurefromafluid-loadedbi-laminatedplateisdescribed.Thebi-laminateiscomposedofapiezoelectriclayerandanelasticlayerincontactwiththefluid,andisheldbyanacousticallyhardbaffle.Inthenumericalmodel,thefluidpressureatfluid/solidinterfaceisreplacedbyacontinuumofpointsourcesweightedbythenormalaccelerationoftheelasticplate,andthegoverningequationsystemissolvedinthesoliddomain.Withthenormalaccelerationfound,thereflectedpressureinthefluidisdeterminedbyanintegralexpressioninvolv-ingtheGreen’sfunction.Itisdemonstratedthatanappropriateappliedvoltagepotentialacrossthepiezoelec-triclayerhastheeffectofcancellingeitherthereflectedorscatteredpressureoftheplateatanychosenfieldpointsinthefluid.
简介:这份报纸论述方法由压电的生成器从沥青人行道收获机械精力。结果证明在沥青人行道的势能能每公里每小巷直到150kW/h。机械精力的部分能被压电的变换器收获。七个典型变换器的表演通过有限元素分析被检验。PZT堆的结果表演并且多层,在沥青人行道环境的钗钹和桥罐头工作。PZT堆积并且多层更高让精力变换评价。然而,如果这些变换器在人行道直接被嵌入,全部的收获精力是小的。一个原型人行道发电机用PZT堆积被开发增加收获精力。发电机能在交通拥挤下面从人行道收获超过50kW/h精力。816PZT堆积为一个发电机被推荐。圆形状被建议让PZT堆积减少应力的集中。并且多层的结构被推荐因为PZT堆发电机的电的潜力到减少。生成器能在沥青人行道作为传感器被扩大,它能被用来监视交通,人行道压力和温度。
简介:Thepotentialforharvestingenergyfromaflexibledeltawingusingapiezoelectricbimorphisexperimentallyinvestigated.Differentconfigurationsoftheproposedharvestingsystemweretestedinawindtunneloverabroadrangeofairspeeds.Inadditiontoevaluatingthelevelofharvestedpower,ananalysisisperformedtoextractcriticalaspectsfortherelationbetweenspeed,flexibility,geometryandthepotentialpowerthatcanbeharvestedfromaclamped,cantileveredflexibledeltawingatlowanglesofattackandlowspeeds.Thisanalysisprovidesaninsightintoparametersthatimpactenergyharvestingfromflexiblemembranesorelements.
简介:Thepressurereflectedfromabi-laminatedpiezoelectricplatehasbeendeterminedusingtheThomson-Haskellmatrixmethod.Theplateiscomposedofapiezoelectriclayerwithgroundedvacuumandanelasticlayerincontactwiththefluid.Anincidentplanewaveinthefluidmediumstrikestheplateatdif-ferentangles.Therequiredelectricpotentialacrossthepiezoelectriclayertocancelthereflectionfromthefluid/elasticboundaryhasbeendeterminedforthepiezoelectricmaterialPZT-5atvariousthicknessparame-lersandincidentfrequencies.
简介:Thefiniteelementformulationforanalyzingstaticdamagenearaconductingcrackinathinpiezoelectricplateisestablishedfromthevirtualworkprincipleofpiezoelectricity.Thedamagefieldsundervariousmechanicalandelectricalloadsarecalculatedcarefullybyusinganeffectiveiterativeprocedure.Thenumericalresultsshowthatallthedamagefieldsaroundacracktiparefan-shapedandtheelectricfieldappliedhasgreatinfluenceonthemechanicaldamage,whichisrelatedtothepiezoelectricproperties.
简介:Basedonthegeneralsolutionofthree-dimensionalproblemsinpiezoelectricmedium,withthemethodofGreen’sfunctins,axisymmetricboundary-valueproblemsarediscussed.Thepurposeofthisresearchisforanalyzingtheeffectiveonmechanicsandelectricityofthepiezoelectricceramicscausedbyvoidsandinclusions.Thedisplacement,tractionandelectricGreen’sfunctionscorrespondingtocircularringloadsactingintheinteriorofapiezoelectricceramicareobtained.AcylindricalcoordinatesystemisemployedandHankeltransformareappliedwithrespecttoradialcoor-dinates.ExplicitsolutionsforGreen’sfunctionsarepresentedintermsofinfiniteintegralsofLipshitz-Hankeltype.Bysolvingatractionboundary-valueproblem,thesolutionschemeisillustrated.
简介:Anewpiezoelectricpumpcanpumpliquideitherforwardorbackwardandadjusttheflowrate.Thusanobjectcanbedrivenforwardorbackwardatdifferentspeeds.Thedriverofthepump,acircularpiezoelectricplate,ismodelledbyFiniteElementMethod(FEM)inANSYSanditsperformanceissimulatedandanalyzed.Thepumpgivesthebestperformancewhenthedrivingsignalsoftheinletandoutletvalveshaveabiggerdutycycleandtheplatehasahighervoltageapplied.