简介：BasedontheEMMSmodel,thelocalslipvelocitybetweengasandsolidissystematicallyanalyzedandatheoreticalcorrelationoflocalslipvelocitywithlocalvoidageforadownerisderivedasfollows:us(r)/ut=D8/7(1-εmf)-2/7[1-ε(r)/ε(r)]8/7ε(r)47/14ε(r)-εmf/ε(r).Usingthiscorrelation,thelocalgas-solidslipvelocityinadowneriscalculated.Thecalculatedresultsarewellconsistentwithexperimentaldata.Inaddition,thevariationofthelocalslipvelocitywithitscorrespondingsolidholdupisalsodiscussed.

简介：Metamaterialsareartificialcompositematerialsengineeredtohavepropertiesthatmaynotbefoundinnature.Byexploringlocallyresonanteffectofthebuildingunits,elasticmetamaterialsareabletopossessnegativevaluesofeffectivemass,effectivebulkorshearmodulus.Mass-springandcontinuummaterialversionsoftheseelasticmetamaterialsarereportedandthephysicalmechanismsofnegativeeffectiveparametersaredemonstrated.Applicationsofmetamaterialstoacousticcloakingandsuperlensingarealsodiscussed.

简介：Theeffectsoftheconstantexcitationonthelocalbifurcationoftheperiodicsolutionsinthe1:2internalresonantsystemswereanalyzedbasedonthesingularitytheory.Itisshownthattheconstantexcitationmakeinfluenceonlywhenthereexistsomenonlinearterms,intheoscillatorwithlowerfrequency.Besidesactingasmainbifurcationparameter,theconstantexcitation,togetherwithcoefficientsofsomenonlinearterms,maychangethevaluesofunfoldingparametersandthetypeofthebifurcation.Underthenon-degeneratecases,theeffectofthethirdordertermscanbeneglected.

简介：Anewmeshfreemethodproposedbytheauthorswaspresented,inwhichthederivativesateachnodewereconstructedusingwholederivativeformulasthroughthenodesselectedaroundthenodeusinglocalCartesianframeinanautonomousmanner,sothatwithoutanyelementitcouldbeconsideredasacompletelymeshfreemethod.Themethodwastestedwithanumericalexample,andreliablesolutionwasobtainedwithhighaccuracyandefficiency.

简介：Biologicalmaterialssuchasbone,tooth,andnacreareload-bearingnanocompositescomposedofmineralandprotein.Sincethemineralcrystalsoftenhaveslendergeometry,thenanocompositesaresusceptibletobuckleunderthecompressiveload.Inthispaper,weanalyzethelocalbucklingbehaviorsofthenanocompositestructureofthebiologicalmaterialsusingabeam-springmodelbywhichwecanconsiderplentyofmineralcrystalsandtheirinteractioninouranalysiscomparedwithexistingstudies.Weshowthatthereisatransitionofthebucklingbehaviorsfromalocalbucklingmodetoaglobalonewhenwecontinuouslyincreasetheaspectratioofmineral,leadingtoanincreaseofthebucklingstrengthwhichlevelsofftothestrengthofthecompositesreinforcedwithcontinuouscrystals.Wefindthatthecontactconditionatthemineraltipshasastrikingeffectonthelocalbucklingmodeatsmallaspectratio,buttheeffectdiminisheswhentheaspectratioislarge.Ouranalysesalsoshowthatthestaggeredarrangementofmineralplaysacentralroleinthestabilityofthebiologicalnanocomposites.

简介：TheIsodynetechniquebasedonthescatteredlightscanningfromathinlaserbeamcanbeusedtoobtaintheinformationinsidetheloadedobjectintheroomtemperaturenondestructively,soitisaverypowerfultechniquein3Dstressanalysis.Theproblemsarehowtointerprettheinformationandhowtogetsufficientinformationfromthefewinterferencefringe.Birefringencephaseshifttechniquecandistinguishthefringeordersautomaticallyandenrichtheinformationin256graylevelsbetweenmaximandminimlightintensity.InthepapertheIsodynebirefringencephaseshiftmethodwithanobliqueincidenceandequilibriumequationispresented,bywhichthe3DstressesinthemiddleplaneofaplatewithUshapenotchareseparatedsuccessfully.

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简介：Thepresentinvestigationofthecrackprobleminpiezoelectricmaterialsisperformedbasedonthenon-localtheory.Aftersomemanipulations,theimpermeablecrack,thepermeablecrack(thecrackgapisfullofNaCIsolution),andthesemi-permeablecrack(thecrackgapisfullofairorsiliconoil)arereducedtoauniformformulationbyassum-ingthenormalelectricdisplacementonthecracksurfacestobeanunknownvariable.Thus,atripleintegralequationwiththeunknownnormalelectricdisplacementisestablished.ByusingtheNewtoniterativemethodandsolvingthetripleinte-gralequation,itisfoundthatthenormalelectricdisplacementonthecracksurfacesisnolongeraconstantasdeterminedbypreviousstudies,rather,itdependsupontheremotecom-binedelectromechanicalloadings.Numericalresultsofthestressesandelectricdisplacementfieldsshowthattherearenosingularitiesatthecracktipssothatthestressesremainfinite.Itisofgreatsignificancethattheconcreteelectricboundaryconditiononthecracksurfacesexertssignificantinfluenceonthenear-tipfieldsandinthiswayplaysanimpor-tantroleinevaluatingthecrackstabilityinthenon-localpiezoelectricmaterials.Morespecifically,theimpermeablecrackmodelalwaysoverestimatesthefinitestressesatthecracktips,whereasthepermeablecrackmodelalwaysunder-estimatesthem.

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简介：Bacterialflagellarfilamentcanundergoastress-inducedpolymorphicphasetransitioninbothvitroandvivoenvironments.Thefilamenthas12differenthelicalforms(phases)characterizedbydifferentpitchlengthsandhelixradii.Whensubjectedtothefrictionalforceofflowingfluid,thefilamentchangesbetweenaleft-handednormalphaseandaright-handedsemi-coiledphaseviaphasenucleationandgrowth.Thispaperdevelopsnon-localfiniteelementmethod(FEM)tosimulatethephasetransitionunderad...

简介：Inthisarticle,thermovibrationanalysisoffunctionallygraded(FG)nanobeamssubjectedtolinearanduniformtemperaturedistributionisstudied.Thestructureismodelledbynewefficientshearbeamtheoryconsideringtheeffectofsheardeformationwithoutshearcorrectionfactor.Thementionedtheorysatisfiesthezeroboundarytractionconditionsonthebeamsurfacesandcanbeusedfortransverseshearstrainstrigonometricdistribution.Materialpropertiesofthenanostructureareassumedtemperature-dependentandFGbasedonthedistributionofpowerlaw.TheinfluenceofsizescaleiscapturedutilisingEringentheoryofnon-localelasticity.