简介：Thescatteringproblemofanti-planeshearwavesinafunctionallygradedmaterialstripwithanoff-centercrackisinvestigatedbyuseofSchmidtmethod.Thecrackisverticallytotheedgeofthestrip.ByusingtheFouriertransform,theproblemcanbesolvedwiththehelpofapairofdualintegralequationsthattheunknownvariableisthejumpofthedisplacementacrossthecracksurfaces.Tosolvethedualintegralequations,thejumpofthedisplacementacrossthecracksurfaceswasexpandedinaseriesofJacobipolynomials.Numericalexampleswereprovidedtoshowtheeffectsoftheparameterdescribingthefunctionallygradedmaterials,thepositionofthecrackandthefrequencyoftheincidentwavesuponthestressintensityfactorsofthecrack.

简介：Intergranularslowcrackgrowthinzirconiapolycrystalisdescribedwithacohesivezonemodelthatsimulatemechanicallythereaction-rupturemechanismunderlyingstressandenvironmentallyassistedfailure.A2Dpolycrystalisconsideredwithcohesivesurfacesinsertedalongthegrainboundaries.Theanisotropicelasticmodulusandgrain-to-grainmisorientationareaccountedfortogetherwithaninitialstressstaterelatedtotheprocessing.Aminimumloadthresholdisshowntooriginatefromtheonsetofthereaction-rupturemechanismtoproceedwhereaminimumtractionisreachedlocallyandfromthemagnitudeoftheinitialcompressionstresses.Thisworkaimsatprovidingreliablepredictionsinlonglastingapplicationsofceramics.

简介：Asolutionispresentedforaclassoftwo-dimensionalelectroelasticbranchedcrackproblems.ExplicitGreen’sfunctionforaninterfacecracksubjecttoanedgedislocationisdevelopedusingtheextendedStrohformulationallowingthebranchedcrackproblemtobeexpressedintermsofcoupledsingularintegralequations.Theintegralequationsareobtainedbythemethodthatmodelsakinkasacontinuousdistributionofedgedislocations,andthedislocationdensityfunctionisdefinedonthelineofthebranchcrackonly.Competitionbetweencrackextensionalongtheinterfaceandkinkingintothesubstrateisinvestigatedusingtheintegralequationsandthemaximumenergyreleaseratecriterion.Numericalresultsarepresentedtoshowtheeffectofelectricfieldonthepathofcrackextension.

简介：AnewmechanicsmodelbasedonPeierlsconceptispresentedinthispaper,whichcanclearlycharacterizetheintrinsicfeaturesnearatipofaninterfacialcrack.Thestressanddisplacementfieldsarecalculatedundergeneralcombinedten-sileandshearloadings.Theneartipstressfieldsshowsomeoscillatorybehaviorsbutwithoutanysingularityandthecrackfacesopencompletelywithoutanyoverlappingwhenremotetensileloadingiscomparablewithremoteshearloading.Afracturecriterionforpredictinginterfacetoughnesshasbeenalsoproposed,whichtakesintoaccountfortheshieldingeffectsofemitteddislocations.Thetheoreticaltoughnesscurvegivesexcellentprediction,ascomparedwiththeexistingexperimentdata.

简介：Fordecades,nacrehasinspiredresearchersbecauseofitssophisticatedhierarchicalstructureandremarkablemechanicalproperties,especiallyitsextremefracturetoughnesscomparedwiththatofitspredominantconstituent,CaCO3,intheformofaragonite.Crackdeflectionhasbeenextensivelyreportedandregardedastheprincipaltougheningmechanismfornacre.Inthispaper,ourattentionisfocusedoncrackevolutioninnacreunderaquasi-staticstate.Weusethenotchedthree-pointbendingtestofdehydratednacreinsituinascanningelectronmicroscope(SEM)tomonitortheevolutionofdamagemechanismsaheadofthecracktip.Theobservationsshowthatthecrackdeflectionactuallyoccursbyconstrainedmicrocracking.Onthebasisofourfindings,acrackpropagationmodelisproposed,whichwillcontributetouncoveringtheunderlyingmechanismsofnacre’sfracturetoughnessanditsdamageevolution.Theseinvestigationswouldbeofgreatvaluetothedesignandsynthesisofnovelbiomimeticmaterials.

简介：Abriefaccountisprovidedoncrack-tipsolutionsthathaverecentlybeenpublishedintheliteraturebyemployingtheso-calledGRADELAmodelanditsvariants.TheGRADELAmodelisasimplegradientelasticitytheoryinvolvingoneinternallengthinadditiontothetwoLame'constants,inanefforttoeliminateelasticsingularitiesanddiscontinuitiesandtointerpretelasticsizeeffects.Thenon-singularstrainsandnon-singular(butsometimessingularorevenhypersingular)stressesderivedthiswayunderdifferentboundaryconditionsdifferfromeachotherandtheirphysicalmeaninginnotclear.Thisisdiscussedwhichfocusontheformandphysicalmeaningofnon-singularsolutionsforcrack-tipstressesandstrainsthatarepossibletoobtainwithintheGRADELAmodelanditsextensions.

简介：Byusingthemethodofstressfunctions,theproblemofmode-ⅡGriffithcrackindecagonalquasicrystalswassolved.First,thecrackproblemoftwo-dimensionalquasicrystalswasdecomposedintoaplanestrainstateproblemsuperposedonanti-planestateproblemandsecondly,byintroducingstressfunctions,the18basicelasticityequationsoncouplingphonon-phasonfieldofdecagonalquasicrystalswerereducedtoasinglehigherorderpartialdifferentialequations.Thesolutionofthisequationundermixedboundaryconditionsofmode-ⅡGriffithcrackwasobtainedintermsofFouriertransformanddualintegralequationsmethods.Allcomponentsofstressesanddisplacementscanbeexpressedbyelementalfunctionsandthestressintensityfactorandthestrainenergyreleaserateweredetermined.

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简介：Experimentalrevelationofsuperbluntingalongplanestrainpredominantcracktipsegmentisre-portedhereformodifiedpolyproplene.Aselucidatedbyaheuristicmodelofprogressivecircumferentialcold-draw,theformationofsuperbluntingcracktipdependscriticallyontheratiobetweenthecold-drawprop-agationspeedandtheloadingspeed,andcontributessignificantlytothematerialtoughening,especiallyfortheimprovementinimpacttoughness.Detailednumericalcalculationsareconductedbasedonahyperelastic-viscoplasticandanisotropicdamageconstitutivemodelatfinitedeformation.Thesimulatedresultsrecapitulatetheessentialfeaturesofcracktipsuperblunting.

简介：在一个磁场使击碎的磁电的身体变形在裂缝附近导致一个使不安的磁场。在在裂缝附近的这块使不安的地和压力之间的量的关系在开发基于磁力的非破坏性的测试技术的新一代是关键的。在这份报纸，使不安的磁场的分析表情由在一个弱外部磁场包含一个集中的裂缝的一个无限的铁磁性的有弹性的盘子的结构的变丑导致了被使用线性化的磁电的理论和Fourier变换方法获得。主要发现是使不安的磁场紧张与应用张力的压力成正比，并且被排水量坡度在磁电的固体的边界上统治。裂缝附近的使不安的磁场的紧张的正切的部件沿着越过它的二张脸严厉地颠倒它的方向的裂缝展出反对称的分布，当正常部件在裂缝尖端与单个点沿着裂缝显示出对称的分布时。

简介：Thepresentstudydevelopsthefracturetheoryforatwo-dimensionaloctagonalquasicrystals.TheexactanalyticsolutionofaModeⅡGriffithcrackinthematerialwasobtainedbyusingtheFouriertransformanddualintegralequationstheory,thenthedisplacementandstressfields,stressintensityfactorandstrainenergyreleaserateweredetermined,thephysicalsenseoftheresultsrelativetophasonandthedifferencebetweenmechanicalbehaviorsofthecrackproblemincrystalandquasicrystalwerefiguredout.Theseprovideimportantinformationforstudyingthedeformationandfractureofthenewsolidphase.

简介：AZener-Strohcrackinteractingwithanedgedislocationisstudied.Thecrackfacesareassumedtobetractionfree.Theapplied'generalizedloading'forcrackistheinitialdisplacementjumpandtheinterventionoftheedgedislocation.Throughdecomposingtheproblemintotwosubsimpleproblems,usingthesuperpositionprinciple,itssolutionisobtained.Todemonstrateboththevalidityofthesolutionanditspotentialapplication,twosimpleexamplesrelatedtothecrackstressintensityfactorsarepre...

简介：Thesystemofawedgedisclinationdipoleinteractingwithaninternalcrackwasinvestigated.Byusingthecomplexvariablemethod,theclosedformsolutionsofcomplexpotentialstothisproblemwerepresented.Theanalyticformulaeofthephysicsvariables,suchasstressintensityfactorsatthetipsofthecrackproducedbythewedgedisclinationdipoleandtheimageforceactingondisclinationdipolecenterwereobtained.Theinfluenceoftheorientation,thedipolearmandthelocationofthedisclinationdipoleonthestressintensityfactorswasdiscussedindetail.Furthermore,theequilibriumpositionofthewedgedisclinationdipolewasalsoexamined.Itisshownthattheshieldingorantishieldingeffectofthewedgedisclinationtothestressintensityfactorsissignificantwhenthedisclinationdipolemovestothecracktips.

简介：Anaccuratecracksurfaceopeningdisplacementformulaforedgecracksinfinitebodieshasbeenderived,andwassubsequentlyusedtodevelopwide-rangeclosed-formweightfunctionsforedgecracks.Theanalyticalweightfunctionisgeneralandcanbeeasilyusedtodetermineaccuratestressintensityfactorsandcracksurfaceopeningdisplacementsforarbitrarilyloadededgecrackswithhighefficiency.Exampleshavebeengivenforproblemsofedgecrack(s)withanumberoftypicalloadconditionsforillustration.

简介：ThecracktipprocessesincopperundermodeⅡloadinghavebeensimulatedbyamoleculardynamicsmethod.Thenucleation,emission,dislocationfreezone(DFZ)andpile-upofthedislocationsareanalyzedbyusingasuitableatomlatticeconfigurationandFinnis&Sinclairpotential.Thesimulatedresultsshowthatthedislocationemittedalwaysexhibitsadissociatedfashion.Thestressintensityfactorfordislocationnucleation,DFZanddissociatedwidthofpartialdislocationsarestronglydependentontheloadingrate.Thestressdistributionsareinagreementwiththeelasticitysolutionbeforethedislocationemission,butarenotinagreementaftertheemission.Thedislocationcanmoveatsubsonicwavespeed(lessthantheshearwavespeed)orattransonicspeed(greaterthantheshearwavespeedbutlessthanthelongitudinalwavespeed),butatthelongitudinalwavespeedtheatomlatticebreaksdown.

简介：Thedisplacementfieldsux,uyatgrowingcracktipofLYI2-Mspecimenswithdoubleedgecracksaremeasuredusingmoiremethod.TheexperimentalsingularityfieldsarecomparedwithGHtheoreticalfield[12-14].ThesizeandshapeoftheexperimentalGHsingularityfieldsareobtained.Theerrorinboththeexperimentalandtheoreticalevaluationsiscontrolledwithin±10%.Theexperimentsshowthatthereis（InA/r）+1singularitydominantaroundagrowingcracktip.Theshapeofthisdominantregionrangesfrombutterflywingtooblateandcircular.InsideGH-field,thereisa3-DdeformeddamagezonewherenoGHsin-gularityexists.

简介：Takingtheshort-fibercompositematerialsasengineeringback-ground,utilizingtheexistingbasicsolutionsofsingleinclusionandsinglecrack,theplaneproblemofverticalcontactinteractionsbetweenlinecrackandrigidlineinclusionininfiniteplane(matrix)fromtheviewpointofcrackfracturemechanicsisstudied.Accordingtoboundaryconditions,asetofstandardCauchy-typesingularintegralequationsoftheproblemisobtainable.Besides,singularindexes,stressesandstressintensityfactorsaroundthecontactpointareexpressed.Numericalexamplesaregiventoprovidereferencestoengineering.

简介：Aso-called“localprobabilisticParisrelationmethod”waspresentedformeasuringtherandomthresholdsoflongfatiguecrackpropagation.Acheckwasmadetotheconventionalmethod,inwhichthethresholdsweremeasuredstatisticallyanddirectlybythetestdata.Itwasrevealedthatthismethodwasnotreasonablebecausethetestdatahaveseldomaunifiedlevelofcrackgrowthrates.Differently,inthepresentedmethodtheParis-Erdoganequationwasappliedtomodelthelocaltestdataaroundthethresholds.Localprobabilisticrelationswithboththesurvivalprobabilityandtheconfidencewereestablishedonalognormaldistributionofthestressdensityfactors.Andthen,theprobabilisticthresholdswerederivedfromtheprobabilisticfactorswithagivencriticallevelofgrowthrate.AnanalysisonthetestdataofLZ50axlesteelfortheChineserailwayvehiclesverifiesthatthepresentmethodisfeasibleandavailable.

简介：Mechanisminteractionbetweencrackswithdifferentorientationanglesisanalyzedbasedontheprincipleofsuperpositionandaflatteningmethod.Itisfoundthatthemaximuminteractioneffectdoesnotoccurwhenthemicrocrackisalongthedirectionparallelorperpendiculartotheprincipaltensilestress,whichisdifferentfromtheconclusiondrawnbyOrtiz(1987).Themechanismofmicrocrackgenerationandtheeffectofthemicrocrackzoneonthemaincracktiparestudied.Itisconcludedthatthemicrocrackzonehaseffectonthemaincracktip,whichincreaseswiththeincreaseofmicrocrackdensityandlength.