简介:Asolutionispresentedforaclassoftwo-dimensionalelectroelasticbranchedcrackproblems.ExplicitGreen’sfunctionforaninterfacecracksubjecttoanedgedislocationisdevelopedusingtheextendedStrohformulationallowingthebranchedcrackproblemtobeexpressedintermsofcoupledsingularintegralequations.Theintegralequationsareobtainedbythemethodthatmodelsakinkasacontinuousdistributionofedgedislocations,andthedislocationdensityfunctionisdefinedonthelineofthebranchcrackonly.Competitionbetweencrackextensionalongtheinterfaceandkinkingintothesubstrateisinvestigatedusingtheintegralequationsandthemaximumenergyreleaseratecriterion.Numericalresultsarepresentedtoshowtheeffectofelectricfieldonthepathofcrackextension.
简介:Anewformofdamagetheoryofmaterialsisproposed,thatisvalidforthecaseofnonconservativestresses.Thepartialentropy,strainandmicrostructureparametersaretakenasthestatevariables.Withoutassumingthefreeenergytobeastatefunction,thebasicgoverningequationsarederived.Accordingtothebalanceofreleasedanddissipatedenergy,thegeneralformofdamageevolutionequationisobtained.Further,assumingtheexistenceofindependentdamagemechanisms,thenormalityofdamageevolutionequationisproven.Thegeneralizeddamagevariablesaredis-cussed.Finally,someexamplesaregiventoshowtheapplicationsofthetheory.
简介:Thispaperisconcernedwiththemodelingofrandomnessinmultiscaleanalysisofheterogeneousmaterials.Morespecifically,aframeworkdedicatedtothestochasticmodelingofrandompropertiesisfirstintroduced.Aprobabilisticmodelformatrix-valuedsecond-orderrandomfieldswithsymmetrypropertries,recentlyproposedintheliterature,isfurtherreviewed.AlgorithmsadaptedtotheMonteCarlosimulationoftheproposedrepresentationarealsoprovided.Thederivationsandcalibrationprocedurearefinallyexemplifiedthroughthemodelingoftheapparentpropertiesassociatedwithanelasticporousmicrostructurecontainingstochasticinterphases.
简介:Mostofgranularmaterialsarehighlyheterogeneous,composedofvoidsandparticleswithdifferentsizesandshapes.Geologicalmatter,soilandclayinnature,geostructure,concrete,etc.arepracticalexamplesamongthem.Fromthemicroscopicview,alocalregioninthemediumisoccupiedbyparticleswith
简介:Recently,intelligentorsmartmaterialsandstructureshavebeenreceivedmoreandmoreattentionduetotheirdistinguishedmulti-fieldcouplingpropertiesandwideapplicationsinaerospace,automobiles,civilstructures,medicaldevices,informationstorage,energyharvestingandsoon.Itisofacademicchallengetofullyunderstandthecomplexmulti-fieldcouplingbehaviorsofvarioussmartmaterialsandstructures,andofengineeringsignificancetoenhancetheperformanceandreliabilityofthese
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.
简介:Thispaperreviewsthestudiesonacoustoelectriceffectinextrinsicsemiconductormaterialsusedinvariousscientificandothermeasurements.Ahistoricalreviewofearlierfindingsisgivenwithspecialreferencetoassociatedmechanisms.Acoustoelectricstudiesinsolidstatedevioesrequirefurtherattentionandtheworkdoneinthisareaisalsodiscussed.
简介:Theeffectofmaterialanisotropyonthebifurcationforvoidtormationinanisotropiccompressiblehyperelasticmaterialsisexamined.Numericalsolutionsareobtainedinananisotropicsphere,whosematerialistransverselyisotropicintheradialdirection.Itisshownthatthebifurcationmayoccureithertotherightortotheleft,dependingonthedegreeofmaterialanisotropy.Thedeformationandstresscontributioninthespherebeforecavitationaredifferentfromthoseaftercavitation.Thestabilityofsolutionsisdiscussedthroughacomparisonofenergy.
简介:Fracturetoughnessisoneofthecrucialmechanicalpropertiesofbrittlematerialssuchasglassesandceramicswhichdemonstratecatastrophicfailuremodes.Conventionalstandardizedtestingmethodsadoptedforfracturetoughnessdeterminationrequirelargespecimenstosatisfytheplanestraincondition.Asforsmallspecimens,indentationisapopular,sometimesexclusivetestingmodetodeterminefracturetoughnessforitcanbeperformedonasmallflatareaofthespecimensurface.Thisreviewfocusesonthedevelopmentofindentationfracturetheoriesandtherepresentativetestingmethods.Crackingpatterndependentonindentergeometryandmaterialpropertyplaysanimportantroleinmodeling,andisthemainreasonforthediversityofindentationfracturetheoriesandtestingmethods.Alongwiththesimplicityofspecimenrequirementisthecomplexityofmodelingandanalysiswhichaccountsforthesemi-empiricalfeaturesofindentationfracturetests.Someunresolvedissuesshapingthegapbetweenindentationfracturetestsandstandardizationarealsodiscussed.更多还原
简介:Nanocarbonmaterialsplayacriticalroleinthedevelopmentofneworimprovedtechnologiesanddevicesforsustainableproductionanduseofrenewableenergy.Thisperspectivepaperdefinessomeofthetrendsandoutlooksinthisexcitingarea,withtheeffortofevidencingsomeofthepossibilitiesofferedfromthegrowinglevelofknowledge,astestifiedfromtheexponentiallyrisingnumberofpublications,andputtingbasesforamorerationaldesignofthesenanomaterials.Thebasicmembersofthenewcarbonfamilyarefullerene,graphene,andcarbonnanotube.Derivedfromthemarecarbonquantumdots,nanohorn,nanofiber,nanoribbon,nanocapsulate,nanocageandothernanomorphologies.Secondgenerationnanocarbonsarethosewhichhavebeenmodifiedbysurfacefunctionalizationordopingwithheteroatomstocreatespecifictailoredproperties.Thethirdgenerationofnanocarbonsisthenanoarchitecturedsupramolecularhybridsorcompositesofthefirstandsecondgenerationnanocarbons,orwithorganicorinorganicspecies.Theadvantagesofthenewcarbonmaterials,relatingtothefieldofsustainableenergy,arediscussed,evidencingtheuniquepropertiesthattheyofferfordevelopingnextgenerationsolardevicesandenergystoragesolutions.
简介:Thecoupledelasticandelectricfieldsforanisotropicpiezoelectricmaterialswithelectri-callypermeablecracksareanalyzedbyusingStrohformulainanisotropicelasticity.ItisshownfromthesolutionthatthetangentcomponentoftheelectricfieldstrengthandthenormalcomponentoftheelectricdisplacementalongthefacesofcracksareaUconstants,andtheelectricfieldintensityandelec-tricdisplacementhavethesingularityoftype(1/2)atthecracktip.Theenergyreleaserateforcrackpropagationdependsonboththestressintensityfactorandmaterialconstants.Theelectricfieldinten-sityandelectricdisplacementinsideelectricallypermeablecracksareallconstants.