简介：Inordertopredictthemechanicalperformanceofthepolyvinylchloride(PVC)atahighoperatingtemperature,aseriesofshort-termtensilecreeptests(onetenthofthephysicalagingtime)ofthePVCarecarriedoutat63Cwithasmallconstantstressbyadynamicmechanicalanalyzer(DMA).TheStruik-Kohlrausch(SK)formulaandStruikshiftingmethodsareusedtodescribethesecreepdataforvariousphysicalagingtime.AnewphenomenologicalmodelbasedonthemultiplerelaxationmechanismsofanamorphouspolymerisdevelopedtoquantitativelycharacterizetheSKparameters(theinitialcreepcompliance,thecharacteristicretardationtime,andtheshapefactor)determinedbytheagingtime.ItisshownthatthemomentarycreepcompliancecurveofthePVCat63CcanbeverywellfittedbytheSKformulaforeachagingtime.However,theSKparametersforthecreepcurvesarenotconstantduringtheagingprocessattheelevatedtemperatures,andtheevolutionoftheseparametersandthecreeprateversusagingtimecurvesatthedoublelogarithmiccoordinateshaveshownanonlinearphenomenon.Moreover,thecreepmastercurvesobtainedbythesuperpositionwiththeStruikshiftingmethodsareunsatisfactoryinsuchacase.Finally,thepredictedresultscalculatedfromthepresentmodelincorporatingwiththeSKformulaareinexcellentagreementwiththecreepexperimentaldataforthePVCisothermallyagedatthetemperaturerelativelyclosetotheglasstransitiontemperature.

简介：U-shapedmicro-nanochannelscangeneratesignificantflowdisturbanceaswellaslocallyamplifiedelectricfield,whichgivesitselfpotentialtobemicrofluidicmixers,electrokineticpumps,andevencelllysisprocess.NumericalsimulationisutilizedinthisworktostudythehiddencharacteristicsoftheU-shapedmicro-nanochannelsystem,andtheeffectsofkeycontrollingparameters(theexternalvoltageandpressure)onthedeviceoutputmetrics(current,maximumvaluesofelectricfield,shearstressandflowvelocity)wereevaluated.Alargeportionofcurrentflowingthroughthewholesystemgoesthroughthenanochannels,ratherthanthemiddlepartofthemicrochannel,withitsvalueincreasinglinearlywiththeincreaseofvoltage.Duetothelocaliondepletionnearmicro-nanofluidicjunction,significantlyenhancedelectricfield(asmuchas15foldatV=1VandP0=0)aswellasstrongshearstress(leadingtoelectrokineticflow)isgenerated.Withincreasingexternalpressure,bothelectricfieldandshearstresscanbeincreasedinitially(duetoshorteningofdepletionregionlength),butaresuppressedeventuallyathigherpressureduetothedestructionofiondepletionlayer.Insightsgainedfromthisstudycouldbeusefulfordesigningnonlinearelectrokineticpumpsandothersystems.

简介：ThisisoneoftheapplicationsofPart(Ⅰ),inwhichtheangularstiffness,andthecorrespondingstressdistributionsofU-shapedbellowswerediscussed.Thebellowswasdividedintoprotrudingsections,concavesectionsandringplatesforthecalculationthatthegeneralsolution(Ⅰ)withitsreducedformtoringplateswereusedrespectively,butthecontinuityofthesurfacestressesandthemeridianrotationsateachjointofthesectionswereentirelysatisfied.Thepresentresultswerecomparedwiththoseoftheslenderringshellsolutionproposedearlierbytheauthors,thestandardsoftheExpansionJointManufacturersAssociation(EJMA),theexperimentandthefiniteelementmethod.Itisshownthatthegoverningequationandthegeneralsolution(Ⅰ)areveryeffective.

简介：Thispaperfollowstheworkof[1,2].Therearesomeprogressindealingwithmoderatelysmallrotations(thesquaresofrotationanglesaretheorderofmagnitudeofstrains)ofmiddlesurfacenormalsofinsideandoutsideringshellsandcompressedangleofbellows.Calculationresultsagreewithexperimentswell.Tobellowdesign,themethodgiveninthispaperisofpracticalvalueandthediscussionoftheinfluenceofcompressedangleoncharacteristicrelationishelpful.