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:TheArrheniuslawimpliesthatreactionrateisacontinuousfunctionoftemperature.However,thesteadylaminarflameletmodel(SLFM)doesnotexplicitlygivethisfunctionalrelationship.ThepresentstudyaddressesthisrelationintheSLFM.Itisfoundthatreactionrateisnotcontinuousinthemixture-fractionspace.Asaresult,theSLFMisunabletopredictlocalextinctionandreignition.Furthermore,weusetheunstablebranchofthe"S-curve"tofillthegapbetweensteadyburningbranchandextinctio...
简介:Viscoelasticityandtemperaturecansignificantlyafecttheperformanceofadielectricelastomer.Inthecurrentstudy,weuseathermodynamicmodeltodescribetheefectoftemperatureandviscoelasticityontheelectromechanicalresponseundergoingacyclicelectricloadbytakingintoaccountofthetemperaturedependentdielectricconstant.Becauseofthesignificantviscoelasticityinthedielectricelastomer,thedeformationandthenominalelectricdisplacementcannotkeepinphasewiththeelectricfieldatlowfrequencies.Theresultsshowthatthemagnitudeofthecyclicelectromechanicalactuationstrainincreaseswiththedecreaseofthetemperatureanddecreaseswiththeincreasingfrequency,andviscoelasticitycanresultinsignificanthysteresisfordielectricelastomersunderarelativelowtemperatureandalowfrequency.
简介:Acousticfatiguelifeevaluationisessentialforthermalprotectionstructuresduetotheseverethermo-acousticloadinservice.AstudyontemperaturedependenceofacousticfatiguelifeforaC/SiCpanelispresentedinthispaper.EffectsoftemperatureonboththestructuralresponsesandtheS–Ncurvesareinvestigated.TheDirlikmethodisadoptedtopredictthefatiguelifeofaC/SiCpanelatthreedifferenttemperaturesrespectively.Significantdifferencesareobservedfromtheresultsofnumericalsimulationsbetweenthefatiguelivesofthepanelinthethreecases.Thetemperature-dependenceofacousticfatiguelifeofaC/SiCpanelisverified,andfatiguetestofthematerialneedstobemoreattentivelyperformed.
简介:Thermalcontactresistanceplaysaveryimportantroleinheattransferefficiencyandthermomechanicalcouplingresponsebetweentwomaterials,andacommonmethodtoreducethethermalcontactresistanceistofillasoftinterfacematerialbetweenthesetwomaterials.AtestingsystemofhightemperaturethermalcontactresistancebasedonINSTRON8874isestablishedinthepresentpaper,whichcanachieve600Cattheinterface.Basedonthissystem,thethermalcontactresistancebetweensuperalloyGH600ma...
简介:在房间温度的第一次干燥的压路机颤动milling被用来准备活跃的碳(交流)nano粒子并且作为电极材料搽粉修改MnO2。在30min交流是到有增加的crystallinity和更高特定的表面区域的3050nm的一种吝啬的粒子尺寸的milled,主要mesoporous并且与改进毛孔直径分发。然后,交流nano粒子与MnO2被合并或做铋的MnO2nano粒子由solgel方法综合了为学习他们的电气化学的表演准备nano合成的电极材料。交流nano粒子与做铋的MnO2nano粒子被发现与增加电流与特定的电容拥有优秀电气化学的性质直到308F/g并且没有明显的变细的10wt.%结合了。我们的方法似乎打开一个新方法改进基于的电极材料为象超级电容器那样的干净精力使用了的交流。
简介:Bymeansofadoublemirrorinterferometryatwo-dimensionaltemperaturedistributionmeasurementinconvectivethermalboundarylayersispresented.Whenthecoldairflowsalongahotplatemodel,theinterferometricfringeinsidetheboundarylayerwillbend.Accordingtothedisplacementofthefringeandtherelationbetweentemperatureandindexofrefraction,atwo-dimensionaltemperatureprofileisobtained.Allisaccomplishedbyopticaldevicewiththehelpofmicro-computerwithoutanycontactwiththeflowfield.
简介:有在紧张和压缩的不同moduli的材料被称为双性人模量材料。Graphene是有最高的力量和最薄的厚度的如此的一种材料。在这份报纸,受到温度效果并且放了在Winkler地基上的双性人模量横梁的机械反应被学习。关于中立的轴位置和双性人模量基础横梁的正常紧张的未经决定的参数的微分方程被建立。然后,地基横梁的正常压力,弯曲时刻,和排水量的分析表情被导出。同时,一个计算过程基于有限元素方法(女性)被开发获得双性人模量结构的温度压力。获得的双性人模量解决方案能恢复古典模量解决方案,这被显示出,并且结果由分析表达式,现在的女性的过程,和传统的女性的软件获得是一致的,它验证现在的分析模型和过程的精确性和可靠性。最后,双性人模量结果之间的差别和古典一样的模量结果被讨论,并且为在实际工程计算并且优化某些双性人模量成员的几个合理建议被介绍。
简介:Inarecentstudy,aregimechartwasestablishedforshearedgranularsystems.Forasoftparticlesystemundersimpleshear,theinternalstressshowedarangeofratedependency.Astheparticleconcentrationincreased,thesystemtransitionedfromakineticgastoaplasticsolid.Thistransitionwasgradualforlowstiffnesssystemsbutbecamemoreabruptasthestiffnessincreased.Inthisstudy,therelationshipbetweenthegranulartemperatureandpressureisinvestigatedforthesamesystemofparticles.Thegranulartemperatureisdefinedastheaveragekineticenergyperunitvolumeandthepressureisdefinedasthetraceofthestresstensor.Itisfoundthatthispressure-temperature(P-T)curvedepictsasharpturnwhenthesystemmovesawayfromthekineticgasregime.However,nosignatureisfoundintheP-Trelationshipinotherregimes.
简介:Afiniteelementisestablishedforanalyzingthedynamicalmechanicsanddeformationofsteelframeathightemperaturewhenitisrapidlycooleddownbyspraywaterinfirefighting.Thesimulationresultshowsthatremarkablemechanicalcouplingeffectsareproducedintheprocess,andthesectionalstressinrapidcoolingdownisfoundconsiderablylargerthanthatinheating-up.Meanwhile,thestressanddeformationofabeammainlyrelatedtocoolingrateandlocationaremuchlargerthanthoseofacolumninrapidcooling.Infirefighting,thestructureonthefirstorsecondfloorwasmoredangerousthanthoseonotherfloorsinrapidcooling.Theseresultscouldprovideatheoreticalreferenceforthedesignofsteelstructureandfirefighting.
简介:Inthispaper,theKirchhoffstransformationispopularizedtothenonlinearheatconductionproblemwhichtheheatconductivitycanbeexpressdasamultinomialoftemperaturefirstly,theboundaryconditionofheatconductionproblemisdeterminedbyanalytics.Secondly,theincubationperoidsuperpositionandthelinearcombinationlawisemployedtosimulatethetransientphassestransformationintheprocessofheattreatmentofmaterials.Thatthebegintimeofphasetransformation,thetypeofphasetransformationandtheamountofphaseconstitutionisdeterminedsimply.Finally,thethree-dimensionDualReciprocityBoundaryElementMethodisusedtoanalysisthetotalprocessofvariousheattreatmentofcomponent,theresultsofnumericalcalculationofexamplesshowthatthemethodprovidedinthispaperiseffectivce.
简介:NanofluidswerepreparedbydispersingCunanoparticles(~20nm)inn-tetradecanebyatwo-stepmethod.Theeffectivethermalconductivitywasmeasuredforvariousnanoparticlevolumefractions(0.0001-0.02)andtemperatures(306.22-452.66K).TheexperimentaldatacompareswellwiththeJangandChoimodel.Thethermalconductivityenhancementwaslowerabove391.06Kthanforthatbetween306.22and360.77K.Theinterfacialthermalresistanceincreasedwithincreasingtemperature.Theeffectivethermalconductivityenhancementwasgreaterthanthatobtainedwithamoreviscousfluidasthebasemediaat452.66KbecauseofnanoconvectioninducedbynanoparticleBrownianmotionathightemperature.
简介:Thispaperfocusesontheeffectoftemperatureontheout-of-planecompressivepropertiesandfailuremechanismofcarbonfiber/epoxycompositepyramidaltrusscoressandwichpanels(CF/CPTSP).CF/CPTSPwithnovelreinforcedframesaremanufacturedbythewaterjetcuttingandinterlockingassemblymethodinthispaper.Thetheoreticalanalysisispresentedtopredicttheout-of-planecompressivestiffnessandstrengthofCF/CPTSPatdifferentambienttemperatures.Thetestsofcompositesandwichpanelsareperformedthroughoutthetemperaturerangefrom-90℃to180℃.Goodagreementisfoundbetweentheoreticalpredictionsandexperimentalmeasurements.ExperimentalresultsindicatethatthelowtemperatureincreasesthecompressivestiffnessandstrengthofCF/CPTSP.However,thehightemperaturecausesthedegradationofthecompressivestiffnessandstrength.Meanwhile,theeffectsoftemperatureonthefailuremodeofcompositesandwichpanelsarealsoobserved.
简介:这份报纸与可变的墙温度在一个垂直的可渗透的锥上讨论micropolarnanofluid的自然传送对流边界层流动。非类似的答案被获得。在管理流动的边界层近似下面的非线性地联合的微分方程用一个有效、反复的、tri斜的、含蓄的有限差别方法数字地被解决。为两nanofluid的不同试验性的关联有效粘性和nanofluid热电导率被考虑。作为旋涡粘性参数增加,两个都,速度介绍,这被发现并且本地Nusselt数字减少。在在这调查考虑的所有nanoparticles之中,另外,Cu给好传送对流。