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184 个结果
  • 简介:Asolutionispresentedforaclassoftwo-dimensionalelectroelasticbranchedcrackproblems.ExplicitGreen’sfunctionforaninterfacecracksubjecttoanedgedislocationisdevelopedusingtheextendedStrohformulationallowingthebranchedcrackproblemtobeexpressedintermsofcoupledsingularintegralequations.Theintegralequationsareobtainedbythemethodthatmodelsakinkasacontinuousdistributionofedgedislocations,andthedislocationdensityfunctionisdefinedonthelineofthebranchcrackonly.Competitionbetweencrackextensionalongtheinterfaceandkinkingintothesubstrateisinvestigatedusingtheintegralequationsandthemaximumenergyreleaseratecriterion.Numericalresultsarepresentedtoshowtheeffectofelectricfieldonthepathofcrackextension.

  • 标签: PIEZOELECTRIC CRACK FRACTURE DISLOCATION BIMATERIAL
  • 简介:Anewformofdamagetheoryofmaterialsisproposed,thatisvalidforthecaseofnonconservativestresses.Thepartialentropy,strainandmicrostructureparametersaretakenasthestatevariables.Withoutassumingthefreeenergytobeastatefunction,thebasicgoverningequationsarederived.Accordingtothebalanceofreleasedanddissipatedenergy,thegeneralformofdamageevolutionequationisobtained.Further,assumingtheexistenceofindependentdamagemechanisms,thenormalityofdamageevolutionequationisproven.Thegeneralizeddamagevariablesaredis-cussed.Finally,someexamplesaregiventoshowtheapplicationsofthetheory.

  • 标签: STATE FUNCTIONS CONSTRAINED VARIABLES DAMAGE evolution
  • 简介:Thispaperisconcernedwiththemodelingofrandomnessinmultiscaleanalysisofheterogeneousmaterials.Morespecifically,aframeworkdedicatedtothestochasticmodelingofrandompropertiesisfirstintroduced.Aprobabilisticmodelformatrix-valuedsecond-orderrandomfieldswithsymmetrypropertries,recentlyproposedintheliterature,isfurtherreviewed.AlgorithmsadaptedtotheMonteCarlosimulationoftheproposedrepresentationarealsoprovided.Thederivationsandcalibrationprocedurearefinallyexemplifiedthroughthemodelingoftheapparentpropertiesassociatedwithanelasticporousmicrostructurecontainingstochasticinterphases.

  • 标签: 建模框架 多孔材料 随机性 非线性行为 界面 应用
  • 简介:Mostofgranularmaterialsarehighlyheterogeneous,composedofvoidsandparticleswithdifferentsizesandshapes.Geologicalmatter,soilandclayinnature,geostructure,concrete,etc.arepracticalexamplesamongthem.Fromthemicroscopicview,alocalregioninthemediumisoccupiedbyparticleswith

  • 标签: 颗粒状物料 计算力学 编辑 颗粒材料 局部区域 颗粒组成
  • 简介:Recently,intelligentorsmartmaterialsandstructureshavebeenreceivedmoreandmoreattentionduetotheirdistinguishedmulti-fieldcouplingpropertiesandwideapplicationsinaerospace,automobiles,civilstructures,medicaldevices,informationstorage,energyharvestingandsoon.Itisofacademicchallengetofullyunderstandthecomplexmulti-fieldcouplingbehaviorsofvarioussmartmaterialsandstructures,andofengineeringsignificancetoenhancetheperformanceandreliabilityofthese

  • 标签: 智能材料 结构力学 编辑 耦合特性 工业应用 航空航天
  • 简介:Ageneralnonlinearconstitutivemodelisproposedformagnetostrictivematerials,basedontheimportantphysicalfactthatanonlinearpartoftheelasticstrainproducedbyapre-stressisrelatedtothemagneticdomainrotationormovementandisresponsibleforthechangeofthemaximummagnetostrictivestrainwiththepre-stress.Toavoidthecomplicityofdeterminingthetensorfunctiondescribingthenonlinearelasticstrainpart,thispaperproposesasimplifiedmodelbymeansoflinearizingthenonlinearfunction.Fortheconvenienceofengineeringapplications,theexpressionsofthe3-D(bulk),2-D(film)and1-D(rod)modelsare,respectively,givenforanisotropicmaterialandtheirapplicablerangesarealsodiscussed.BycomparisonwiththeexperimentaldataofaTerfenol-Drod,itisfoundthattheproposedmodelcanaccuratelypredictthemagnetostrictivestraincurvesinlow,moderateandhighmagneticfieldregionsforvariouscompressivepre-stresslevels.Thenumericalsimulationfurtherillustratesthat,foreithermagnetostrictiverodsorthinfilms,theproposedmodelcaneffectivelydescribetheeffectsofthepre-stressorresidualstressonthemagnetizationandmagnetostrictivestraincurves,whilenoneoftheknownmodelscancaptureallofthem.Therefore,theproposedmodelenjoyshigherprecisionandwiderapplicabilitythanthepreviousmodels,especiallyintheregionofthehighfield.

  • 标签: 非线性模型 磁致伸缩材料 磁致伸缩薄膜 弹性应力 磁场
  • 简介:Thispaperreviewsthestudiesonacoustoelectriceffectinextrinsicsemiconductormaterialsusedinvariousscientificandothermeasurements.Ahistoricalreviewofearlierfindingsisgivenwithspecialreferencetoassociatedmechanisms.Acoustoelectricstudiesinsolidstatedevioesrequirefurtherattentionandtheworkdoneinthisareaisalsodiscussed.

  • 标签: HISTORICAL EARLIER extreme EXTRINSIC MOMENTUM RELAXATION
  • 简介:Theeffectofmaterialanisotropyonthebifurcationforvoidtormationinanisotropiccompressiblehyperelasticmaterialsisexamined.Numericalsolutionsareobtainedinananisotropicsphere,whosematerialistransverselyisotropicintheradialdirection.Itisshownthatthebifurcationmayoccureithertotherightortotheleft,dependingonthedegreeofmaterialanisotropy.Thedeformationandstresscontributioninthespherebeforecavitationaredifferentfromthoseaftercavitation.Thestabilityofsolutionsisdiscussedthroughacomparisonofenergy.

  • 标签: 各向异性材料 空穴分支 能量对比 压缩超弹性材料 材料力学 数值分析
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  • 简介:Fracturetoughnessisoneofthecrucialmechanicalpropertiesofbrittlematerialssuchasglassesandceramicswhichdemonstratecatastrophicfailuremodes.Conventionalstandardizedtestingmethodsadoptedforfracturetoughnessdeterminationrequirelargespecimenstosatisfytheplanestraincondition.Asforsmallspecimens,indentationisapopular,sometimesexclusivetestingmodetodeterminefracturetoughnessforitcanbeperformedonasmallflatareaofthespecimensurface.Thisreviewfocusesonthedevelopmentofindentationfracturetheoriesandtherepresentativetestingmethods.Crackingpatterndependentonindentergeometryandmaterialpropertyplaysanimportantroleinmodeling,andisthemainreasonforthediversityofindentationfracturetheoriesandtestingmethods.Alongwiththesimplicityofspecimenrequirementisthecomplexityofmodelingandanalysiswhichaccountsforthesemi-empiricalfeaturesofindentationfracturetests.Someunresolvedissuesshapingthegapbetweenindentationfracturetestsandstandardizationarealsodiscussed.更多还原

  • 标签: 断裂韧性 脆性材料 压痕法 测定 平面应变 测试方法
  • 简介:Nanocarbonmaterialsplayacriticalroleinthedevelopmentofneworimprovedtechnologiesanddevicesforsustainableproductionanduseofrenewableenergy.Thisperspectivepaperdefinessomeofthetrendsandoutlooksinthisexcitingarea,withtheeffortofevidencingsomeofthepossibilitiesofferedfromthegrowinglevelofknowledge,astestifiedfromtheexponentiallyrisingnumberofpublications,andputtingbasesforamorerationaldesignofthesenanomaterials.Thebasicmembersofthenewcarbonfamilyarefullerene,graphene,andcarbonnanotube.Derivedfromthemarecarbonquantumdots,nanohorn,nanofiber,nanoribbon,nanocapsulate,nanocageandothernanomorphologies.Secondgenerationnanocarbonsarethosewhichhavebeenmodifiedbysurfacefunctionalizationordopingwithheteroatomstocreatespecifictailoredproperties.Thethirdgenerationofnanocarbonsisthenanoarchitecturedsupramolecularhybridsorcompositesofthefirstandsecondgenerationnanocarbons,orwithorganicorinorganicspecies.Theadvantagesofthenewcarbonmaterials,relatingtothefieldofsustainableenergy,arediscussed,evidencingtheuniquepropertiesthattheyofferfordevelopingnextgenerationsolardevicesandenergystoragesolutions.

  • 标签: 纳米碳材料 可再生能源 应用 存储解决方案 可持续生产 太阳能装置
  • 简介:Thecoupledelasticandelectricfieldsforanisotropicpiezoelectricmaterialswithelectri-callypermeablecracksareanalyzedbyusingStrohformulainanisotropicelasticity.ItisshownfromthesolutionthatthetangentcomponentoftheelectricfieldstrengthandthenormalcomponentoftheelectricdisplacementalongthefacesofcracksareaUconstants,andtheelectricfieldintensityandelec-tricdisplacementhavethesingularityoftype(1/2)atthecracktip.Theenergyreleaserateforcrackpropagationdependsonboththestressintensityfactorandmaterialconstants.Theelectricfieldinten-sityandelectricdisplacementinsideelectricallypermeablecracksareallconstants.

  • 标签: PIEZOELECTRIC material CRACK stress INTENSITY FACTOR