ELECTROMECHANICAL ANALYSIS OF PNEUMATICALLY COUPLED DIELECTRIC ELASTOMER ACTUATORS

Abstract

There isagrowinginterestinusingpneumaticallycoupleddielectricelastomer(PCDE)actuators for smartmaterial-basedsystemdesignsduetotheirabilitytoachievelargedeformationswhile maintaining safetyduringpracticalapplications.Theinvolvementofairpressurealsoenhances the performanceofelectromechanicalactuationinDEdevices.However,thehighlynonlinear electromechanical aircouplingbehaviorrequiresaccurateandefficientmodelingapproaches for thedesignanddevelopmentofPCDEactuators.PCDEactuatorsexhibitbothmaterialand geometrical nonlinearities,makingtheirmodelinganddesignmorecomplicated,especiallywith the additionofthecoupledmotionofpneumatically-connectedDE.Asaresult,thisareaof research hasthepotentialtoyieldmoreadvancedstructuresforourindustrialsociety. Herein, thepresentthesisdealswiththestudyofdeformationproblemsconcerningthe constitutivemodelingofnonlinearbehaviorofthePCDEactuatorswithintheframeworkofthe classical continuummechanics-basedapproach.Primarily,fivebroadtopicsarecovered:(i) an analytical modelwithoutconsideringtheaircolumneffectoftheinflatedvisco-hyperelastic dielectric elastomeractuators(DEAs)forinvestigatingthedynamicperformance, (ii) an analytical modelwiththeaircolumneffectoftheinflatedvisco-hyperelasticdielectric elastomer actuators(DEAs), (iii) an analyticalframeworktoinvestigatethequasi-static and dynamicresponseofactiveandpassivesidesinPCDEactuatorconsideringviscoelastic material, (iv) implementation thePCDEactuatorin’Adaptiveoptics’applicationand developaprototypeofDE-basedvariablefocallengthreflector(DE-VFLR), and(v) presentationanideaofmultilayeredDE-basedcompositewithananalyticalframework forthealleviationofmaterialviscoelasticity. Eachtopicplaysavitalroleinthetheoretical, experimental,andcomputationaladvancementofsmartstructuremodelinginsoftactuation technology. The firstproblemexploresthedevelopmentofanenergy-basedanalyticalmodelpertaining to theelectromechanicalresponseofthepressure-inflateddielectricvisco-elastomer.Thisis accomplished byapplyingaZenerrheologicalmodelalongsidetheGenthyperelasticitymodel for thepolymerfilmandthedifferentialpressureworkofair.Theproposedanalyticalframework and thematerialmodelsareimplementedintoanin-houseMATLABprogramandutilized to predicttheattainedequilibriumstates,DCandACresponse,andthepressure-inflatedDE actuator periodicityoverfeasibleviscosityrangeparameters. The secondproblemexploresanenergy-basedanalyticalmodelbyimpartingaconfinedair column effecttotheelectromechanicalresponseofpressure-inflateddielectricvisco-elastomer. This isaccomplishedbyapplyingtheideaofapseudo-airspringalongsidetheneo-Hookean hyperelasticitymodelforthepolymerfilm.Theproposedmodelinvestigatestheeffectofthe mass oftheconfinedaircolumnontheDCandACresponse,theresonancebehavior,andthe periodicity oftheinflatedactuatoroverafeasiblerangeofviscoelasticparameters,inflation pressure, andelectricfield.Inaddition,theformulatedmodelbasedontheproposedmethod is comparedandvalidatedwithanexperimentalstudy. The thirdproblemincorporatestheideaofapseudo-airspringintheenergy-basedap- proach toinvestigatetheelectromechanicaldynamicresponseofthePCDEactuator.This is accomplishedbyapplyingtheconceptofpseudoairspringtopneumaticallyconnectthe motion oftwopressure-inflatedactiveandpassivedielectricvisco-elastomeralongsidetheneo- Hookeanhyperelasticitymodelforthepolymerfilm.Air-springisresponsiblefortransferring the electromechanicaldeformationfromtheactivetothepassivesidemembrane.Thepredictive capability oftheproposedanalyticalmodelisestablishedthroughcomparisonswithexperimental observations.Thedevelopednonlineardynamicmodelisthenusedforbuildinginsightsinto severalinfluentialparameters,suchasinitialinflationpressure,time-dependent(DCandAC) electric actuation,theheightoftheconfinedaircolumn,thevolumeoftheinterveningchamber, etc.