外文翻译数字模拟冲击试验机的多液压缸电动液压的系统和控制器设计.docx

外文翻译数字模拟冲击试验机的多液压缸电动液压的系统和控制器设计.docx

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外文翻译数字模拟冲击试验机的多液压缸电动液压的系统和控制器设计

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英文原文

NUMERICALMODELINGOFMULTICYLINDERELECTRO-HYDRAULICSYSTEMANDCONTROLLERDESIGNFORSHOCKTESTMACHINE

Abstract：

Ahighfidelitydynamicmodelofahigh-energyhydraulically-actuatedshocktestmachineforheavyweightdevicesispresentedtosatisfythenewly-builtshockresistancestandardandsimulatetheactua1underwaterexplosionenvironmentsinlaboratoryaswel1asincreasethetestingcapabilityofshocktestmachine．Inordertoproducetherequirednegativeshockpulseinthegiventimeduration．fourhydraulicactuatorsareutilized．Themodelisthenusedtoformulateanadvancedfeedforwardcontrollerforthesystemtoproducetherequirednegativewaveformandtoaddressthemotionsynchronizationofthefourcylinders．Themode1providesasafeandeasilycontrollablewaytoperforma“virtua1testing”beforestartingpotentiallydestructivetestsonspecimenandtopredictperformanceofthesystem．Simulationresultshavedemonstratedtheeffectivenessofthecontroller.

Keywords：

ShocktestmachineNegativeshockpulseActuatorredundancyFeedforwardcontrollerVirtua1testing

0INTRODUCTION

Theeffectsofunderwaterexplosions（UNDEX）onshiphullsandequipmenthavebeenstudiedsincethel800sLU．Non-contactunderwaterexplosionsagainstsurfaceships，i．e．bymines，ormissilesmaycauseextensiveequipmentdamageandrendershipsinoperativeeventhoughhulldamageisnotcritica1．Thusshocktestmustbecarriedoutoneverycriticaldeviceorequipmentonsubmarineandsurfaceshiptoconfirmthatitwillstillfunction．orinsevercaseswillsurvive，aftertheoccurrenceoftheshockconditionswhichitcanbeexpectedtoencounterduringitsservice．Themosteffectiveanddirectwaytocheckouttheanti—shockcapabilityofdevicesistotestthemonavesselsubjectedtounderwaterexplosion．Testsconductedusingliveexplosiveshaveinherentlimitationsincludingenvironmentalimpact，significantcost，measuringresultsinthefieldandavailablequantityoftests．Atpresent，thecommonlyusedmethodtoassesswarshipequipment’sshockresistancecapabilityistoconducttestonashocktestmachineinacontrollableway．

TheUNDEXenvironmentisverycomplex．composedofa“kick”fromtheincidentshockwavefollowedbytheeffectsofcavitations，bubblepulse，andstructuralwhipping．Thebubblepulseoscillatesatafrequencyveryclosetothefirstbendingmodeoftheship．ItwillbeevenmoredestructivethantheincidentpressurewavewhenthebubblemigratesnearenoughtotheshiptoexcitethismodeHowever,thetraditionalshockmachines．1ikelightweightshockmachine（LWSM）andmediumweightshockmachine（MWSM），cannotsimulateshockenvironmentforthebubblepulsesinducedbyUNDEX．andtheshockenvironmentsimulatedbytraditionalmachinesislargelydifferentfromtheactualUNDEXphysicalenvironment．AccordingtothenewlydesignspecificationsOfMIL．S．90lD．theinputforshocktestshouldbeshockresponsespectra（SRS1，insteadofasingletime．history．accelerationwaveformsuchashalf-sine．triangularsawtoothpulse．Besides．theshockinputinthedesignspecificationsOfBV043／85isadoubletransientshockpulse．i．e．apositiveaccelerationpulseanegativeone.IntheorytheSRScanbetransformedintotimedomainanditisequivalenttoadouble．waveforil1．Therefore．shockmachinesthatwillbebuiltshouldadapttotherequirementofthelatestshockcriteriontosimulatetheactualUNDEXenvironmentasmuchaspossible．

Theaimofshocktestingistoimpartprecisereplicationsofhigh．energytransientshockpulseintotestspecimens．Thetestspecimensarevaluableandunique，andneedtobetestedtoexactshocklevelswithspecificenterspectra：

toomuchcandamagethespecimen，toolittleleavesquestionsaboutthespecimenrobustness．Owingtothetestseverity,itisthenessentialthatthetestshouldbecontrollable．Classiccontrolmethods，suchaspoleplacement．havebeeninvestigatedforshockcontrol，butwithlimitedsuccess．Themainreasonisthatthedurationofshocktestisveryshort．bythetimethesystemcandetectanerrorbetweencommandsandtheactualoutputs．itisalreadytoolatetorespondadequately．

Thispaperformulatesahighfidelitynumericaldynamicmodelforadampingsystem．whichisapartofthewholeshockmachineusedtoproducetherequirednegativeshockpulseinthetestingprocess．Componentsofthesystemmodelareusedtoformelateanadvancedfeedforwardcontroller．Theactuatorredundancyissueisalsoconsideredduringthecontrollerdesign．Themodelandcontrollerprovideasafeandeasilycontrollablewaytoperforma’virtualtesting”beforestartingpotentiallydestructivetestsonthespecimenandtopredicttheperformanceofthesystem．Furtherore．inordertosolvetheuncertaintyproblemofthetestspecimendynamicsforfeedforwardinversemodelcontrol，anewinitialtuningtechniqueisproposedforourspecialcases．

Theorganizationofthispa1）erisasfollows：

Insectionl，adescriptionofthedampingsystemanditsdynamicmodelispresented．Variousfeaturesofthemodelarediscussed，includingthesettlementofactuatorsredundant．Insection2．thecontrolstrategiesareproposed．Thesimulationresultsarepresentedinsection3．Finally,theconclusionsectionfollows．

1PROBLEMFORMULATIONANDDYNAMICMODEL

ThestructureofthedampingsystemisshowninFig．1anditsfunctionistoproducetherequirednegativeshockpulseduringshocktestingprocess．Thedurationoftheshockwavetransientsisunder0．1s．withdesiredaccelerationsupto25～50gformegiventestspecimenalltheseparameterscanbeadjustedaccordingtodifferenttestingconditions．Thetestingcapacityofmeshockmachineisunder5000kg（includingfixture）．Thetestspecimenisfixedonmeteststandmovingverticallyatmegivenspeed，whichisproducedbytheshocksysteminmepositiveshockpulsegeneratingprocess．Whenthemaximumspeedisachieved，the

dampingsystembeginstoforceittostopinthegiventime

Themaindifficultyindesigningthedampingsystemliesinthatthesystemshouldproducetherequiredforcesinthegiventimetosaristhewaveformrequirement．Forthispurpose,fourcomplexandsophisticatedhydraulicactuatorsaredesignedtoexertthedampingforces．Theactuatorsareconnectedwiththeteststandthroughsphericalhingesandthefourram-typecylindersarearrangedinasymmetricalmanner．DetailsofthecontactingpointsbetweenteststandandcylinderscanbeseeninFig．2．Thepointsontheteststandthatcontactthecylindersvarywiththerotationoftheteststand．Itsmotiondependsontherotationangleand．Inrealitytherotationangleisverysmall，thismotioncanbeignoredandwejustfocusontheverticaldisplace．MendandtherotationalongtherollaxisrandthepitchaxisP．Eachcylinderiscontrolledbyfourthree．stageservovalves．Thehightransientenergyissuppliedbyaseriesofaccumulators（seeFig．3）

1.1Systemmodeling

Inwhatfollowing．mathematicalmodelofthecomponentsinthenegativepulsesystemwillbebuiltindetail．

1.1.1Testspecimen

Fig．1showstheforcesactingonthehydrauliccylindersandFig．4isthetopviewofthesystemtoindicatethelocationofthespecimen．Sphericalcontactsurfacesareassumedbetweenthecylindersandtheteststand．Theteststand（includingtestspecimen）canrotatefreelyaroundtherollaxisrandthepitchaxisP．Therol1axisrisdefinedtobeperpendiculartothe1ineconnectingcylinder1andcylinder2andthepitchaxisPisdefinedtobeparalleltothelineconnectingcylinder1andcylinder2．AccordingtoNewton’ssecondlawandthetheoremofangularmomenturn，thefollowingequationscanbeobtainedtorepresentthemotionofthespecimen.

wherem：

ms+mt，msandmtrepresentmassofthetestspecimenandtheteststand，respectively．representsthereactionforceactingoncylinder（i=1，2，3，4）；gisthegravitationalconstant；Iiand12arethemomentam1forwithrespecttotherotationalaxisrandP；jandJvrepresenttherotationalmomentofinertiaoftheloadabouttheaxisrandaxisp；8rand8，aretherotationangleabouttheaxisrandaxispFIandFIrepresentthefrictionforcebetweentheteststandandcylindersalongthedirectionoftheaxis，andaxisp；aandbrepresentoff-centerdistancesofthespecimenwithrespecttotheteststandcenterO1；02isthegravitycenterofthetestspecimen．

1.1.2Hydrauliccylinders

ConsidertheforcesFA（1，2，3，4）actingonthecylinders，theequationsofmotionforthecylinderscanbeexpressedasfollows

wherepirepresentsthepressureinthechamberofcylinderIand4representstheeffectivepistonarea；mrepresentsthepistonmassofcylinder．Firepresentsthefrictionforce；lrepresentstheviscousdampingcoefficient．

Thecontactingeffectbetweentheteststandardthecylindercanbeassumedtobeequivalenttoamassspring-dampersystemwithstiffnessanddampingratio，andthenthecontactingeffectcanbemodeledbythefollowingequation

whererepresentstherelativedisplacementofthecontactpointbetweentheteststandandthecylinders．

1.1.3Cylinderpressure

Thepressureineachcylinderiscontrolledbyservovalves．Considerthecompressibilityofthefluidinthecylindersaswellastheleakages，thepressuredifferentialequationsgoverningthedynamicsoftheactuatorcanbeexpressedasfollows

where（x）=a+v，and（x）representsthetotalactuatorvolumeandisdefinedtobethefluidvolumeeofthehosesfromthevalveprostatecylinderi．frepresentstheloadflowofcylinderi．representsspoolvalveareagradient．Krepresentstheeffectivebulkmodulus．Cmrepresentsthecoefficientofleakage．Cdrepresentsdischargecoefficient．Psrepresentsthes