动态控制参数的含义Dyncontrol.docx

动态控制参数的含义Dyncontrol.docx

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动态控制参数的含义Dyncontrol

ControlParameter

3

StaticLoadCaseforNonlinearRestraintStatus

动态分析是线性的分析，在开始建立分析模型之前，我们选择哪个工况作为开始。

STATICLOADCASEFORNONLINEARRESTRAINTSTATUS

（Activefor:

Harmonic,Spectrum,Modal,Range,andTimeHistory）

CurrentlyallofCAESARII'sdynamicanalysesactonlyonlinearsystems,soanynon-linearitiesmustbelinearizedpriortoanalysis.Thismeansthatone-directionalrestraintswillnotliftoffandreseat,gapswillnotopenandclose,andfrictionwillnotactasaconstanteffortforce.Therefore,fordynamicanalyses,allnon-lineareffectsmustbemodeledaslinear-forexample,aone-directionalrestraintmustbemodeledaseitherseated（active）orliftedoff（inactive）,andagapmustbeeitheropen（inactive）orclosed（active）.Thisprocessisautomatedwhenthestaticloadcaseisselectedhere-CAESARIIautomaticallyactivatesthenon-linearrestraintsinthesystemtocorrespondtotheirstatusintheselectedloadcase（theusermaythinkofthisasbeingtheloadingcondition-forexampleOperating-ofthesystematthetimeatwhichthedynamicloadoccurs）.Itmustbenotedthatthisautomatedlinearizationdoesnotalwaysprovideanappropriatedynamicmodel,anditmaybenecessarytoselectotherstaticloadcasesoreventomanuallyaltertherestraintconditioninordertosimulatethecorrectdynamicresponse.

Astaticloadcasemustprecedethedynamicsjobwhenever:

1）Therearespringhangerstobedesignedinthejob.Thestaticrunsmustbemadeinordertodeterminethespringratetobeusedinthedynamicmodel.

2）Therearenon-linearrestraints,suchasone-directionalrestraints,large-rotationrods,bi-linearrestraints,gaps,etc.inthesystem.Thestaticanalysismustbemadeinordertodeterminetheactivestatusofeachoftherestraintsforlinearizationofthedynamicmodel.

3）Therearefrictionalrestraintsinthejob,i.e.anyrestraintswithanonzero（mu）value.

0.0

StiffnessFactorforFriction（0.0-NotUsed）

解释这个含义

STIFFNESSFACTORFORFRICTION（0.0-NOTUSED）

（Activefor:

Harmonic,Spectrum,Modal,Range,andTimeHistory）

AllofCAESARII'sdynamicanalysesarecurrentlylinear,sonon-lineareffectsmustbelinearized.Modelingoffrictionindynamicmodelspresentsaspecialcase,sincefrictionactuallyimpactsthedynamicresponseintwoways-staticfriction（priortobreakaway）affectsthestiffnessofthesystem,byprovidingadditionalrestraint,whilekineticfriction（subsequenttobreakaway）actuallyaffectsthedampingcomponentofdynamicresponse;duetomathematicalconstraints,dampingisignoredforallanalysesexcepttimehistory（forwhichitisonlyconsideredonasystem-widebasis）.CAESARIIallowsfrictiontobetakenintoaccountthroughtheuseofthisFrictionStiffnessFactor.CAESARIIapproximatestherestrainingeffectoffrictiononthepipebyincludingstiffnessestransversetothedirectionoftherestraintatwhichfrictionwasspecified.Thestiffnessofthese"frictional"restraintsiscomputedas:

Kfriction=（F）*（）*（Fact）

Where:

Kfriction=stiffnessoffrictionalrestraintinsertedbyCAESARII

F=theforceattherestrainttakenfromthestaticsolution

=mu,frictioncoefficientatrestraint,asdefinedinthestaticmodel

Fact=FrictionFactorfromthecontrolspreadsheet

Thisfactorshouldbeadjustedasnecessaryinordertomakethedynamicmodelsimulatethesystem'sactualdynamicresponse（notethatuseofthisfactordoesnotcorrespondtoanyactualdynamicparameter,butisactuallya"tweak"factortomodifysystemstiffness）.Enteringafrictionfactorgreaterthanzerocausesthesefrictionstiffnessestobeinsertedintothedynamicsjob.Increasingthisfactorcorrespondinglyincreasestheeffectofthefriction.Enteringafrictionfactorequaltozeroignoresanyfrictionaleffectinthedynamicsjob.

0

Max.No.ofEigenvaluesCalculated（0-NotUsed）

解释这个含义

MAX.NO.OFEIGENVALUESCALCULATED（0-NOTUSED）

（Activefor:

Spectrum,Modal,andTimeHistory）

ThefirststageoftheSpectrum,Modal,andTimeHistoryanalyses,istheuseoftheEigensolveralgorithmtoextractthepipingsystem'snaturalfrequenciesandmodeshapes.FortheSpectrumandTimeHistoryanalyses,theresponseunderloadingiscalculatedforeachofthemodes,withthesystemresponsebeingthesumoftheindividualmodalresponses.Obviously,themoremodesthatareextracted,themorethesumofthosemodalresponsesresemblestheactualsystemresponse.Theproblemisthatthisalgorithmusesaniterativemethodforfindingsuccessivemodes,soextractionofalargenumberofmodesusuallyrequiresmuchmoretimethandoesastaticsolutionofthesamepipingsystem.Theobjectistoextractsufficientmodestogetasuitablesolution,withoutstrainingcomputationalresources.CAESARI