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Copyright2005ABAQUS,Inc.Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockLecture5深圳ABAQUS培训深圳ANSYS深圳有限元培训培训•AcousticScatteringandShockwithABAQUS•ExampleProblemCopyright2005ABAQUS,Inc.Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUSCopyright2005ABAQUS,Inc.L5.4Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS–ABAQUSprovidesacapabilityforintroducinggeneralizedforcesonacousticandsolidmediaassociatedwiththearrivalofdilatationalwaves.•Thisappliestoacousticscatteringproblemsandproblemsinvolvingblastloadsinairorwater.–Inadynamicprobleminvolvingfluidandcoupledsoliddomains,excitedbyapropagatingwaveinthefluidarrivingfromoutsidethedomain,wavefieldsinthefluidcanbesuperimposed,sincethefluidmechanicsisassumedlinear.–Theobservedtotalpressureinthefluidcanthusbedecomposedintotwocomponents:theknownincidentfield,andthewavefieldduetoreflectionsatfluidboundariesandinteractionswiththesolid.–Thislatterfieldisreferredtoasthe‘scattered’field,andcanbecomputedsimplybyapplyingloadsatthefluid-solidinterfacethatcorrespondtotheeffectsoftheincidentwavefield.Copyright2005ABAQUS,Inc.L5.5Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS•Incidentwaveloading–Theexplosiveloadisspecifiedwiththe*INCIDENTWAVEoptionandrelatedsuboptions.•InABAQUS/CAE,theseoptionsisnotcurrentlysupportedandmustbeinvokedusingtheKeywordsEditor.*INCIDENTWAVEisappliedonboththestructureandthefluidattheircommoninterface.–Thisloadisadistributedloadsimilarto*DSLOAD.–Theblastsourcecanbelocatedoutsidetheacousticdomain.–Analysisistrackedbeginningatthestandoffpoint.•Usuallyitisdesirabletohavethestandoffpointlocatedasclosetothestructureaspossible.Copyright2005ABAQUS,Inc.L5.6Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS–Youmustspecifythelocationofsourcepoint(positionofthecharge)andlocationofthestandoffpoint(thepositionwheretheincidentwaveamplitudeisspecified).–ABAQUSwillautomaticallycalculatethespatialandtemporalvariationoftheloadcausedbytheblast.*INCIDENTWAVEissupportedonlyintransientdynamicprocedures.*DYNAMIC(ABAQUS/Standard)*DYNAMIC,EXPLICIT(ABAQUS/Explicit)*INCIDENTWAVEloadingisappliedonlyinthestepinwhichitisspecified.•Ifan*INCIDENTWAVEloadisactiveoverseveralsteps,itmustbespecifiedineachstepinwhichitisactive.Copyright2005ABAQUS,Inc.L5.7Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS•AcousticWaveFormulation–TotalWaveformulation(*ACOUSTICWAVEFORMULATION,TYPE=TOTALWAVE).•Thepressureisthetotalpressureintheacousticmedium,includingtheeffectsoftheincidentwavefieldandtheoverallsystem’sresponse.•Theformulationprovidesacompletesolutionoftheacousticpressurefield(asopposedtoapartialone,whichisobtainedusingtheScatteringWaveformulation).•Requiredwhencavitationisincludedinthemodel.InABAQUS/CAE,thisoptionisnotcurrentlysupportedandmustbeinvokedusingtheKeywordsEditor.Copyright2005ABAQUS,Inc.L5.8Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS–ScatteredWaveformulation(*ACOUSTICWAVEFORMULATION,TYPE=SCATTEREDWAVE)•Basedonthefacttheacousticmediumislinear,theresponsecanbedecomposedintothesumoftheincidentwaveandthescatteredfield.•Modelsonlyresponseofmediumtowaveloads,notthewavepulseitself.•Pressureisscatteredpressureonly.InABAQUS/CAE,thisoptionisnotcurrentlysupportedandmustbeinvokedusingtheKeywordsEditor.Copyright2005ABAQUS,Inc.L5.9Structural-AcousticAnalysiswithABAQUS•Identifyingthefluidandsolidsurfacesfor*INCIDENTWAVEloading–Scatteredwave•Loadingmustbespecifiedonallfluidandsolidsurfacesthatreflecttheincidentwaveexcluding–thosefluidsurfacesthathavepressurevaluesdirectlyprescribedusing*BOUNDARY,and–thosefluidsurfacesthathavesymmetryconditions.•Note:Thesymmetryconditions,ifany,mustholdforboththegeometryandtheloading.AcousticScatteringandShockwithABAQUSCopyright2005ABAQUS,Inc.L5.10Structural-AcousticAnalysiswithABAQUS–Totalwave•Loadingmustbespecifiedonlyonthefluidsurfacesthatbordertheinfiniteregionexcludedfromthemodel.•Typicallythesesurfaceshaveanonreflectingradiationconditionspecifiedonthemaswell.•ABAQUSensuresthattheradiationconditionisenforcedonlyonthescatteredresponseandnotontheincidentwaveitself.AcousticScatteringandShockwithABAQUSCopyright2005ABAQUS,Inc.L5.11Structural-AcousticAnalysiswithABAQUSAcousticScatteringandShockwithABAQUS•Definingthetimehistoryofthesourcepulse–Foranincidentwaveimpingingonasolidsurface,thesourcepulsemustbedefinedbyusingthefluidpressurevaluesatthestandoffpoint.•Forplanarwaveloadingonafluidsurface,thesourcepulsecanbespecifiedeitherintermsofthepressurevaluesortheaccelerationvalues.•Forsphericalwaveloadingonafluidsurface,thesourcepulsemustbespecifiedintermsofthepressurevalues.*INCIDENTWAVE,PRESSUREAMPLITUDE*INCIDENTWAVE,ACCELERATIONAMPLITUDE.Copyright2005ABAQUS,Inc.L5.12Struct