ABAQUS声学分析-acoustics-lecture6.ppt

Structural AcousticAnalysiswithABAQUS AdditionalExamples Lecture6 深圳ABAQUS培训深圳ANSYS培训深圳ANSYS深圳ABAQUS深圳有限元培训ABAQUS培训ANSYS培训 Structural AcousticAnalysiswithABAQUS Overview SloshingEffectofSurfaceTreatmentsonRoomAcousticsNonlinearStructuralBehaviorCoupledPiezoelectricandAcousticAnalysisAcousticsofaTruckCab FullyCoupledAnalysisAcousticsofaTruckCab SequentialAnalysisSummary Structural AcousticAnalysiswithABAQUS Sloshing Structural AcousticAnalysiswithABAQUS Sloshing SphericalacousticradiationinMode1Reference Junger M C andFeit D Sound Structures andTheirInteraction MITPress pp 200 203 1972 PhysicalDescription Asteel r 7800kg m3 E 210GPa n 0 3 sphericalshellofradius1mandthickness0 05misimmersedinaninfinitevolumeofair r 1 25kg m3 K 128000Pa c 320m s Thesphereisdrivenasarigidbodytoexcitemode1usingthe BOUNDARY TYPE DISPLACEMENToption Afrequencyrangeof10Hzto204Hz correspondingtoka 0 2to4 0isanalyzedusing STEADYSTATEDYNAMICS DIRECT Nonconformingshell S8R andacousticinfiniteelement ACIN3D4 meshesareused Fluid solidcouplingthroughuseofthe TIEoption Structural AcousticAnalysiswithABAQUS Sloshing Meshes shellsinorange Structural AcousticAnalysiswithABAQUS Sloshing Pressuremagnitudesat158 7Hz Structural AcousticAnalysiswithABAQUS Sloshing Pressuremagnituderesultsfreq Hz kaNode1776Node35Analytical10 00000000 1963495412 515560002 516710002 5140472912 85690000 2524446414 206560004 208540004 2044314816 53000000 3245657917 080980007 084410007 0783558221 25240000 41728989812 032500012 038600012 030235127 32390000 53650352220 691600020 702600020 692059635 13010000 68977790035 980600036 001400035 987947745 16640000 88684019062 603100062 641500062 610501558 06990001856000105 924000105 79847974 65980001 46594174166 575000166 689000166 27310195 98930001 88474550238 751000238 874000237 975417123 4120002 42318895319 106000319 087000317 622889158 6700003 11547816412 658000412 448000410 202606204 0000004 00553063528 079000527 194000524 385853Analyticalsolution Structural AcousticAnalysiswithABAQUS EffectofSurfaceTreatmentsonRoomAcoustics Structural AcousticAnalysiswithABAQUS EffectofSurfaceTreatmentsonRoomAcoustics Example Smallroomcoupledtoinletandexhaustducts Uniformforcingatinletend Exhausttoexteriormodeledusingasmallhemisphereofairandthesphericalradiationcondition Atthefrequencyshown theinletexcitationhasexcitedastandingwaveintheroom Structural AcousticAnalysiswithABAQUS EffectofSurfaceTreatmentsonRoomAcoustics Acoustic onlymeshofroom ducts andexterior notreatment Structural AcousticAnalysiswithABAQUS EffectofSurfaceTreatmentsonRoomAcoustics Addacoustictreatmentstoceiling wall andfloorofroom Structural AcousticAnalysiswithABAQUS EffectofSurfaceTreatmentsonRoomAcoustics Withacoustictreatment Structural AcousticAnalysiswithABAQUS NonlinearStructuralBehavior Structural AcousticAnalysiswithABAQUS NonlinearStructuralBehavior Structuralanalysiscanincludeeffectsfromseveralsourcesofnonlinearity MaterialnonlinearitiesExamples Metalplasticity crushablefoamGeometricnonlinearitiesExamples Pre tensioningofacable snap throughbehaviorofanarchContactnonlinearitiesContactisinherentlynonlinearbecausethecontactconstraintsareeitheronoroff theydonotvarysmoothly Structural AcousticAnalysiswithABAQUS NonlinearStructuralBehavior MultistepanalysisGeneralanalysisstepscanhavelinearornonlinearbehavior Theendconditionofonegeneralstepprovidesthebasestateforthenextgeneralstep Ifanearliergeneralstepincludesnonlinearbehavior thenonlinearsolutionisincludedinsubsequentsteps Acousticanalysisincludestheeffectsofpreviousnonlineargeneralsteps Themostobviouseffectisaligningtheacousticregionwiththedeformedshapeofthestructure includingcontactregions Lessobviousisthechangeinmaterialproperties suchasstiffness Structural AcousticAnalysiswithABAQUS NonlinearStructuralBehavior Example Soundtransmissionthrougharubberdoorseal Step1 Staticstructuralanalysistodeformtherubbersealintoitsfinalposition Rigidsurfacemovesupward causingtherubbertodeform Acousticmeshisautomaticallyupdatedbasedwiththeuseofadaptivemeshing Structural AcousticAnalysiswithABAQUS NonlinearStructuralBehavior Step2 Steady statedynamicanalysisofthefullycoupledsystem Theairandtherubberinteractthroughtheirtiedsurfaces Acousticpressureisappliedasaboundaryconditiontoleftsideoftheairmesh Deformedsealinacousticmedium Contoursofacousticpressure Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis PiezoelectricanalysisAnelectricpotentialgradientcausesstraining andstresscausesanelectricpotentialgradient Piezoelectricanalysisbyitselfisacoupledelectrical stressanalysis Canbecombinedinamodelwithacousticelementsandthenecessarystructural acousticcoupling Oftenusedinacousticsapplications suchasspeakers Solvedusing FREQUENCY MODALDYNAMIC STEADYSTATEDYNAMICS or STATIC Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis Example fluid coupledmotionofatransducerHalf axisymmetricmodelofpiezoelectricsolid brassheadmass andfluid Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis Applyelectricalforcingacrosspiezoelectricmaterialusingthe DSECHARGEor DECHARGEoptions CoupleacousticfluidtotheheadmasssolidelementsusingTIEconstraints Usewaterpropertiesandfluidelementstoapproximatehumantissue Modelradiationintothefluidexteriorusingthesphericalboundaryimpedance IMPEDANCEPROPERTY TYPE SPHERICAL Sweepthroughfrequenciesusingthe STEADYSTATEDYNAMICS DIRECTproceduretofindonsetofdegradedtransductionduetoheadmassvibration Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis Acousticpressureat36866Hz Structural AcousticAnalysiswithABAQUS CoupledPiezoelectricandAcousticAnalysis Acousticpressureat37342Hz Headmassmodedistortsacousticfield Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Theobjectiveistoshowtheacousticfieldinandsurroundingamodeltruckcabduetotheeffectofloudspeakers Cabstructureismountedonfourelasticpoint mounts modeledassprings Restoftruckisomittedfromthisanalysis Interiorandexteriorairaremeshedautomaticallyusingtetrahedralelements Exteriorradiationismodeledusingsphericalradiationimpedance Cabstructureismodeledusingshellsandsolids fordashboardandseat Acousticexcitationduetoloudspeakersinsidecabismodeledasconcentratedloadsontheacousticfluid Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Exteriorandinteriorfluidmeshesareshownhere Neithermeshmatchesthecabshellmeshnode to node EachismodeledasaseparatepartandcoupledusingtheTIEconstraints Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Inexteriorproblemsitisgoodpracticetoinspectthephaseoftheacousticpressureatthelowestfrequencyofinteresttoseeiftheradiationconditionisperformingproperly Iftheradiationconditionisappliedincorrectly absent ortooclosetotheacousticsources thephasecontourswillshowdistortionneartheboundary Here thecontourslookallright Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Thedirectsteady statedynamicsprocedureisusedtosolvethecoupledfluid solidproblemat90frequencies UsingABAQUS Viewer weobserveapeakinthestructuralmotionamplitudeat110Hz Thisinvolveslargemotionsofthewindshieldandotherpanels Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Theinterioracousticpressurefield POR dB atthisfrequency Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Theexteriorfieldshowsradiationprimarilytothefrontandtop withapeakunderneaththecab Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Anotherstructuralpeakamplitudeoccursat298Hz directlyatthelocationoftheacousticsource Again sideandwindshieldpanelmotionsarethemostpronounced Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab FullyCoupledAnalysis Theexteriorfieldatthisfrequency 298Hz showsradiationfromthewindshieldandsidepanels Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Example TruckcabproblemusingsequentialanalysisThreevariationsarediscussedhere Theydifferonlyintheanalysisprocedureusedfortheglobalmodel Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Firstmethod Directsteady statedynamicsinbothanalysesGlobalmodel Definenodesetsandelementsetsasdescribedpreviously andsavetheneededresultstotheoutputdatabase odb orresults fil file Usedirectsteady statedynamicsoverthedesiredfrequencyrange Submodel Usedirectsteady statedynamicsoverthesamefrequencyrangeorasubsetofthisrange Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Computedporepressure PORdB forexterior below andinterior nextpage acousticfieldsarenearlyidenticaltothefullycoupledresults Global Directsteady statedynamicsSubmodel Directsteady statedynamics Fullycoupled Sequentiallycoupled Structural AcousticAnalysiswithABAQUS Nearlyidenticalbehaviorduetothelowforceamplitudeexertedonthestructurebytheair AcousticsofaTruckCab SequentialAnalysis Fullycoupled Sequentiallycoupled Global Directsteady statedynamicsSubmodel Directsteady statedynamics Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Secondmethod Naturalfrequencyextractionfollowedbymodalsteady statedynamicsintheglobalmodelComputeeigenmodesoftheuncoupledstructuralsystem Runthesteady stateprocedureatthesefrequencies andusetheseresultsastheforcingfunctionsforthesubmodelanalysis ThisprocedurewillIGNOREanydampingduetostructuralmaterialproperties butmodaldampingcanbeapplied Subsequently usedirectsteady statedynamicsfortheacousticssubmodel Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Firsteigenmodeoftheuncoupled undampedstructuralsystemisat108Hz usingfrequencyextractionprocedure Global Modalsteady statedynamicsSubmodel Directsteady statedynamics Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Themodalsteady statedynamicsprocedureyieldsthefollowingsolution displacementmagnitudes atthisfrequency Fullycoupled 110Hz Sequentiallycoupled 108Hz Global Modalsteady statedynamicsSubmodel Directsteady statedynamics Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Thedirectsteady statedynamicsprocedureisusedinthesubmodelatthesamefrequency interiorandexteriorairshown Fullycoupled Sequentiallycoupled Global Modalsteady statedynamicsSubmodel Directsteady statedynamics Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Thirdmethod Naturalfrequencyextractionfollowedbysubspaceprojectionsteady statedynamicsintheglobalmodelThenaturalfrequenciesandmodeshapesarecomputedasinthepreviousprocedure Thesubspaceprojectionsteady statedynamicsprocedureisusedfortheglobalmodel Thisprocedurediffersfromthemodalsteady statedynamicsprocedureinthattheoriginalsystemoffiniteelementequations includingstructuraldampingterms isprojectedontotheeigenmodes Structural AcousticAnalysiswithABAQUS AcousticsofaTruckCab SequentialAnalysis Thestructuralresponsesarereducedcomparedtothos