简介：AfastadaptivesymplecticalgorithmnamedMultiresolutionSymplecticScheme(MSS)wasfirstpresentedtosolvetheproblemofthewavepropagation(WP)incomplexmedia,usingthesymplecticschemeandDaubechies'compactlysupportedorthogonalwavelettransformtorespectivelydiscretisethetimeandspacedimensionofwaveequation.TheproblemwassolvedinmultiresolutionsymplecticgeometryspaceundertheconservativeHamiltoniansystemratherthanthetraditionalLagrangesystem.Duetothefascinatingpropertiesofthewaveletsandsymplecticscheme,MSSisapromisingmethodbecauseoflittlecomputationalburden,robustnessandrealityoflong-timesimulation.

简介：Bytakinginfiniteperiodicbeamsasexamples,themutualvariationalprincipleforanalyzingthefreewavepropagationinperiodicstructuresisestablishedanddemonstratedthroughtheuseofthepropaga-tionconstantinthepresentpaper,andthecorrespondinghierarchicalfiniteelementformulationisthende-rived.Thus,itprovidesthenumericalanalysisofthatproblemwithafirmtheoreticalbasisofvariationalprin-ciples,withwhichonemayconvenientlyillustratethemathematicalandphysicalmechanismsofthewaveprop-agationinperiodicstructuresandtherelationshipwiththenaturalvibration.Thesolutionisdiscussedandex-amplesaregiven.

简介：Aso-called“localprobabilisticParisrelationmethod”waspresentedformeasuringtherandomthresholdsoflongfatiguecrackpropagation.Acheckwasmadetotheconventionalmethod,inwhichthethresholdsweremeasuredstatisticallyanddirectlybythetestdata.Itwasrevealedthatthismethodwasnotreasonablebecausethetestdatahaveseldomaunifiedlevelofcrackgrowthrates.Differently,inthepresentedmethodtheParis-Erdoganequationwasappliedtomodelthelocaltestdataaroundthethresholds.Localprobabilisticrelationswithboththesurvivalprobabilityandtheconfidencewereestablishedonalognormaldistributionofthestressdensityfactors.Andthen,theprobabilisticthresholdswerederivedfromtheprobabilisticfactorswithagivencriticallevelofgrowthrate.AnanalysisonthetestdataofLZ50axlesteelfortheChineserailwayvehiclesverifiesthatthepresentmethodisfeasibleandavailable.

简介：Transmissionofelasticwavesthroughamicrogapbetweentwosolidswithconsiderationoffrictionalcontactisinvestigated.ByusingtheFourieranalysistechniqueandthecorrectivesolutionmethod,thenonlinearboundaryproblemisreducedtoasetofalgebraicequations.Numericalresultsexhibitthelocationsandextentsofseparation,slip,andstickzones,theinterfacetractions,andtheenergypartition.Theeffectsofgapwidth,frictionalcoefficients,andtheincidentangleonthewavetransmissionarediscussedindetail.Theresultsshowthathigherharmonicsaregeneratedduetothelocalcontact/slipattheinterface.

简介：Withtheadventofleft-handedmagneticmaterials,itisdesirabletodevelophigh-performancewavedevicesbasedontheirnovelpropertiesofwavepropagation.Thisletterreportsthespecialpropertiesofelasticwavepropagationinmagnetoelasticmultilayeredcompositeswithnegativepermeabilityascomparecdtothoseincounterpartstructureswithpositlvepermeability.Thesenovelpropertiesofelasticwavesarediscernedfromthediversifieddispersioncurves,whichrepresentthepropagationandattenuationcharacteristicsofelasticwaves.Tocomputethesedispersioncurves,themethodofreverberation-raymatrixisextendedfortheanalysisofelasticwavesinmagnctoelasticmultilayeredcomposites.Althoughonlytheresultsofasinglepiezomagneticandabinarymagnetoelasticlayerswithmechanicallyfreeandmagneticallyshortsurfacesaswellaspelrfectinterfaceareillustratedinthenumericalexamples,theanalysisisapplicablelomagnetoelasticmultilayeredstructureswithotherkindsofboundaries/interfaces.

简介：Thispaperpresentsacomputationalmodelforthefluiddynamicsinafracturedductilepipeunderhighpressure.Thepressureprofileinfrontofthecracktip,whichisthedrivingsourceofcrackpropagation,iscomputedusinganonlinearwaveequation.Thesolutioniscoupledwithaonedimensionalchokedflowanalysisbehindthecrack.Thesimulationutilizesahighorderoptimizedprefactoredcompact-finitevolumemethodinspace,andlowdispersionanddissipationRunge-Kuttaintime.Asthepipefracturestherapiddepressurizationtakeplaceinsidethepipeandthepropagationofthecrack-inducedwavesstronglyinfluencestheoutflowdynamics.Consistentwiththeexperimentalobservation,themodelpredictstheexpansionwaveinsidethepipe,andthereflectionandoutflowofthewave.Themodelalsohelpscharacterizethepropagationofthecrackdynamicsandfluidflowsaroundthetipofthecrack.

简介：Basedonthemultiplescatteringmethod,thispaperinvestigatesabenchmarkproblemofthepropagationofliquidsurfacewavesoverfinitegraphene(orhoneycomb)structuredarraysofcylinders.Comparingthegraphenestructuredarraywiththesquarestructuredandwithtrianglestructuredarrays,itfindsthatthefinitegraphenestructurecanproducemorecompletebandgapsthantheotherfinitestructures,andthefinitegraphenestructurehaslesslocalizedabilitythantheotherfinitestructures.

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简介：Thispaperinvestigatesthedamagedetectionbasedonthepropagationofguidedwaveinbimetalcompositepipes,whichcanidentifydamagelocationsinbothaxialandcircumferentialdirections.ThefeasibilityofthemethodisshowedbynumericalsimulationsusingFEMcodeANSYS.Modeanalysisisusedtoevaluatetheguidedwavemodeanditsstructure,whichcanprovidethebasisofthemodeselectioninmeasurementsscheme.Theguidedwavepropagationinadamagedpipeiscomputedbytransientanalysis.16...

简介：AnewlydevelopedZfracturecriterionforthecompositematerialswasintroduced,thenewconceptsofin-planeaveragestrain,in-planedilatationalstrainenergydensityfactorandreciprocalcharacteristicfunctionwerepresented.ManyexperimentalresultsshowthattheZfracturecriterioncanbewellusedtopredictthecrackpropagatingdirectionformodeⅠcrackincarbon-fiberreinforcedcompositelaminates.

简介：Investigationsontheinterconnectionbetweenthepolarizationrotationandcrackpropagationareperformedfor[110]-oriented74Pb(Mg1/3Nb2/3)O3-26PbTiO3relaxorferroelectricsinglecrystalunderelectricloadingsalong[001]direction.ThecrystalisofpredominantlymonoclinicMAphasewithscatterdistributedrhombohedral(R)phaseunderamoderatepolingfieldof900V/mmin[001]direction.Withmagnitudeof800V/mm,athroughthicknesscrackisinitiatedneartheelectrodebyelectriccycling.Staticelectricloadingsisthenimposedtothesinglecrystal.Astheappliedstaticelectricfieldincreases,domainswitchinginthemonoclinicMAphaseandphasetransitionfromMAtoRphaseoccurnearthecrack.Theresultsindicatethatthecrackfeaturesaconductingone.Whetherdomainswitchingorphasetransitionoccursdependsontheintensityoftheelectricfieldcomponentthatisperpendiculartotheappliedelectricfield.

简介：RandomfatigueofweldedK-typetubularjointssubjectedtoaxialorout-of-planebendingloadisanalyzed.Byconsideringthesizesofinitialsurfacecracksandmaterialconstantsasrandomvariableswithsomeprobabilisticdistributions,incorporatingtheeffectoftheweld,fivehundredrandomsamplesaregenerated.Statisticalcomputationalresultsoflifeofcrackpropagationandeffectofchangeofcrackshapearefinallyobtainedandcomparedwithexperimentaldataavailablebasedonaregressionanalysis.Meanwhile,crackpropagationbehaviorsarealsoinvestigated.

简介：Wavepropagationanalysisforafunctionallygradednanobeamwithrectangularcross-sectionrestingonvisco-Pasternak'sfoundationisstudiedinthispaper.Timoshenko'sbeammodelandnonlocalelasticitytheoryareemployedforformulationoftheproblem.TheequationsofmotionarederivedusingHamilton'sprincipalsbycalculatingkineticenergy,strainenergyandworkduetoviscoelasticfoundation.Theeffectsofvariousparameterssuchaswavenumber,non-homogeneousindex,nonlocalparameterandthreeparametersoffoundationareperformedonthephasevelocityofthenanobeam.Theobtainedresultsindicatethatsomeparameterssuchasnon-homogeneousindex,nonlocalparameterandwavenumberhavesignificanteffectontheresponseofthesystem.

简介：Theelasticwavepropagationphenomenaintwo-dimensionalperiodicbeamlatticesarestudiedbyusingtheBlochwavetransform.Thenumericalmodelingisappliedtothehexagonalandtherectangularbeamlattices,inwhich,boththein-plane(withrespecttothelatticeplane)andout-of-planewavesareconsidered.ThedispersionrelationsareobtainedbycalculatingtheBlocheigenfrequenciesandeigenmodes.Thefrequencybandgapsareobservedandtheinfluenceoftheelasticandgeometricpropertiesoftheprimitivecellonthebandgapsisstudied.ByanalyzingthephaseandthegroupvelocitiesoftheBlochwavemodes,theanisotropicbehaviorsandthedispersivecharacteristicsofthehexagonalbeamlatticewithrespecttothewavepropagationarehighlightedinhighfrequencydomains.OneimportantresultpresentedhereinisthecomparisonbetweenthefirstBlochwavemodestothemembraneandbending/transverseshearwavemodesoftheclassicalequivalenthomogenizedorthotropicplatemodelofthehexagonalbeamlattice.Itisshownthat,inlowfrequencyranges,thehomogenizedplatemodelcancorrectlyrepresentboththein-planeandout-of-planedynamicbehaviorsofthebeamlattice,itsfrequencyvaliditydomaincanbepreciselyevaluatedthankstotheBlochmodalanalysis.Asanotherimportantandoriginalresult,wehavehighlightedtheexistenceoftheretropropagatingBlochwavemodeswithanegativegroupvelocity,andofthecorresponding'retro-propagating'frequencybands.

简介：Thepropagationofshockwavesinacellularbarissystematicallystudiedintheframeworkofcontinuumsolidsbyadoptingtwoidealizedmaterialmodels,viz.thedynamicrigid,perfectlyplastic,locking(D-R-PP-L)modelandthedynamicrigid,linearhardeningplastic,locking(D-R-LHP-L)model,bothconsideringtheeffectsofstrain-rateonthematerialproperties.Theshockwavespeedrelevanttothesetwomodelsisderived.ConsiderthecaseofabarmadeofoneofsuchmaterialwithinitiallengthL0andinitialvelocityviimpingingontoarigidtarget.Thevariationsofthestress,strain,particlevelocity,specificinternalenergyacrosstheshockwaveandtheceasedistanceofshockwavearealldeterminedanalytically.Inparticularthe'energyconservationcondition'andthe'kinematicexistencecondition'asproposedbyTanetal.(2005)isre-examined,showingthatthe'energyconservationcondition'andtheconsequent'criticalvelocity',i.e.theshockcanonlybegeneratedandsustainedinR-PP-Lbarswhentheimpactvelocityisabovethiscriticalvelocity,isincorrect.Instead,withelasticdeformation,strain-hardeningandstrain-ratesensitivityofthecellularmaterialsbeingconsidered,itisappropriatetoredefineafirstandasecondcriticalimpactvelocityfortheexistenceandpropagationofshockwavesincellularsolids.StartingfromthebasicrelationsforshockwavepropagatinginD-R-LHP-Lcellularmaterials,anewmethodforinverselydeterminingthedynamicstress-straincurveforcellularmaterialsisproposed.Byusinge.g.acombinationofTaylorbarandHopkinsonpressurebarimpactexperimentaltechnique,thedynamicstress-straincurveofaluminumfoamcouldbedetermined.Finally,itisdemonstratedthatthisnewformulationofshocktheoryinthisone-dimensionalstressstatecanbegeneralizedtoshocksinaone-dimensionalstrainstate,i.e.forthecaseofplateimpactoncellularmaterials,bysimplymakingproperreplacementsoftheelasticandplasticconstant

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