简介：Inthispaper,anonlocaltheoryoffractureforbrittlematerialshasbeensystematicallydevel-oped,whichiscomposedofthenonlocalelasticstressfieldsofGriffithcracksofmode-Ⅰ,ⅡandⅢ,theasymptoticformsofthestressfieldsattheneighborhoodofthecracktips,andthemaximumtensilestresscriterionforbrittlefracture.Asanapplicationofthetheory,thefracturecriteriaofcracksofmode-Ⅰ,Ⅱ,ⅢandmixedmodeⅠ-Ⅱ,Ⅰ-Ⅲaregivenindetailandcomparedwithsomeexperimentaldataandthetheoreticalresultsofminimumstrainenergydensityfactor.

简介：Fracturetoughnessisoneofthecrucialmechanicalpropertiesofbrittlematerialssuchasglassesandceramicswhichdemonstratecatastrophicfailuremodes.Conventionalstandardizedtestingmethodsadoptedforfracturetoughnessdeterminationrequirelargespecimenstosatisfytheplanestraincondition.Asforsmallspecimens,indentationisapopular,sometimesexclusivetestingmodetodeterminefracturetoughnessforitcanbeperformedonasmallflatareaofthespecimensurface.Thisreviewfocusesonthedevelopmentofindentationfracturetheoriesandtherepresentativetestingmethods.Crackingpatterndependentonindentergeometryandmaterialpropertyplaysanimportantroleinmodeling,andisthemainreasonforthediversityofindentationfracturetheoriesandtestingmethods.Alongwiththesimplicityofspecimenrequirementisthecomplexityofmodelingandanalysiswhichaccountsforthesemi-empiricalfeaturesofindentationfracturetests.Someunresolvedissuesshapingthegapbetweenindentationfracturetestsandstandardizationarealsodiscussed.更多还原

简介：Mechanicalandelectricaldamagesareintroducedtostudythefracturemechanicsofpiezoelectricceramicsinthispaper.Twokindsofpiezoelectricfracturecriteriaareestablishedusingthemethodofleastsquarescombinedwithadamageanalysisofthewell-knownpiezoelectricfractureexperimentsofParkandSun's.Oneisbasedonalinearcombinationofthemechanicalandelectricaldamagesandtheotherontheirnonlinearcombination.WhenthecombineddamageDisuptoitscriticalvalueDc,piezoelectricfractureoccurs.Itisfoundfromthequalitativecomparisonofthenumericalresultswiththeexperimentaldatathatthenonlinearlycombineddamagefracturecriterioncangiveabetterpredictionofpiezoelectricfracture.Anditisconcludedfromthenonlinearlycombineddamagefracturecriterionthatanegativeelectricfieldimpedesfracturewhereastheeffectofapositiveelectricfieldonfracturedependsonitsmagnitude.

简介：Thisinvestigationdiscussesfurthertheextenttowhichanewdamagetheoryrecentlyproposedbytheauthorcanserveasaunifiedtheorytocharacter-izevariousductilefailureproblems.Ageneraldamageintegralandcorrespondingcriterionforductilefracturearepresented.Anewparameterforductilefractureisemphasized,whichisexperimentallyverifiedasamaterialconstantindependentofstressstate,hasclearphysicalmeaning,andcaneasilybedetermined.Theapplica-bilityofthistheorytoevaluationoftheductilityofweldsandengineeringmaterialsundervariousconditionsisexamined.Also,itisusedtopredicttheeffectofresid-ualstressonfailureofwelds,topredictsheetforminglimits,andtocorrelatethevariabilityofelasto-plasticfracturetoughnessvaluesJ1candδcwithdifferentspec-imengeometries.Anewconstraintcorrectionmethodisproposed,andconstraintcorrectednewtoughnessparametersJdcandδdcarerecommended.Experimentshaveshownthatthetoughnessvariationwithdifferentspecimengeometriescanef-fectivelyberemovedbyuseofthemethod.Thegeneralapplicabilityofthetheorytocharacterizationofvariousductilefailuresprovidesanewdesigntoolforengineeringcomponentsorstructures.

简介：在一台半导体设备构造一根相连的金属线的原子被电子流动在高密度搬运。这现象被称为electromigration，它可以引起线失败。以便描绘electromigration失败，比较研究被执行，一些典型现象为薄、大的结构由破裂力学对待。薄结构的一个例子，被破裂力学对待，是硅石为通讯系统的光纤维。在由electromigration的一根金属线的损坏生长在光纤维使遭到了到静态的疲劳的硅石与裂缝生长比较被描绘。另外，简短比较在大结构在electromigration失败和一些破裂现象之间被做。

简介：Inphasefieldfracturemodelsthevalueoftheorderparameterdistinguishesbetweenbrokenandundamagedmaterial.Atcrackfacestheorderparameterinterpolatessmoothlybetweenthesetwostatesofthematerial,whichcanberegardedasphases.Thecrackevolutionfollowsimplicitlyfromthetimeintegrationofanevolutionequationoftheorderparameter,whichiscoupledtothemechanicalfieldequations.Amongotherphenomenaphasefieldfracturemodelsareabletoreproducecracknucleationininitiallysoundmaterials.Fora1Dsettingithasbeenshownthatcracknucleationistriggeredbythelossofstabilityoftheunfractured,spatiallyhomogeneoussolution,andthatthestabilitypointdependsonthesizeoftheconsideredstructure.Thisworknumericallyinvestigatestowhichextendsizeeffectsarereproducedbythe2Dphasefieldmodel.Exemplarily,afiniteelementstudyoftheholesizeeffectisperformedandthesimulationresultsarecomparedtoexperimentaldata.

简介：Theacousticemission(AE)featuresinrockfracturearesimulatednumericallywithdiscreteelementmodel(DEM).Thespecimenisconstructedbyusingsphericalparticlesbondedviatheparallelbondmodel.Asaresultoftheheterogeneityinrockspecimen,thefailurecriterionofbondedparticleiscoupledbytheshearandtensilestrengths,whichfollowanormalprobabilitydistribution.TheKaisereffectissimulatedinthefractureprocess,foracubicrockspecimenunderuniaxialcompressionwithaconstantrate.TheAEnumberisestimatedwithbreakagesofbondedparticlesusingapairofparameters,inthetemporalandspatialscale,respectively.ItisfoundthattheAEnumbersandtheelasticenergyreleasecurvescoincide.TherangefortheKaisereffectfromtheAEnumberandtheelasticenergyreleasearethesame.Furthermore,thefrequency-magnituderelationoftheAEnumbershowsthatthevalueofBdeterminedwithDEMisconsistentwiththeexperimentaldata.

简介：Thepurposeofthisworkistoinvestigatethedynamicfracturepropertiesofglassypolycarbonate(PC)withdiferentagingtimes.Theopticalmethodofcausticsisadoptedinwhichtheshadowspotpatternsarerecordedbyahighspeedcameraduringthedynamicfractureprocess.Then,thedynamiccrackpropagation,thestressintensityfactor(SIF)andthedynamicfracturetoughnessofagedPCareobtainedthroughananalysisofthecharacteristicsizeofcausticpattern.Moreover,bycombiningwiththeinvestigationofthefracturesurfaceandtheenergyreleaserateanalysis,theinfluenceofagingtimeonthedynamicfracturebehaviorisdiscussed.ResultsshowthatthedynamicfracturetoughnessandcriticalenergyreleaserateofPCdecreaseswithagingtimeforshortagingtimes,whereastheyhavelittlechangeorevenincreaseforlongeragingtimes.Therefore,agingmodifiesthemechanicalpropertiesespeciallythedynamicfracturepropertiesofPCnonlinearly,notlinearlyasgenerallythoughtof.

简介：这个工作检验包含平行表面的板击碎，轮流出现的长度使遭到了到热震动的机能上地分级的材料(FGM)的破裂行为。在长、短的裂缝的尖端的热压力紧张因素(TSIF)用一种单个不可分的方程技术被计算。引起快克开始的批评热吃惊螖Tc用一个压力紧张因素标准被计算。为一个Al2O3/Si3N4FGM盘子的TSIF和螖Tc的数字例子被举在TSIF和螖Tc上说明热性质阶段，裂缝间距和裂缝长度比率的效果。为给定的裂缝长度比率，在长、短的裂缝的尖端的TSIF能显著地被减少，螖Tc能被介绍适当材料阶段提高，这被发现。TSIF也在裂缝间距与减少戏剧性地减少。在短裂缝的尖端的TSIF可能为在某些裂缝几何学条件下面的长裂缝比那高。因此，短裂缝可以开始首先在装载的热吃惊下面成长而不是长裂缝。

简介：一个基于Hamiltonian的分析方法被用来与一个有瑕疵的接口在magnetoelectroelasticbimaterials学习模式III接口裂缝。由介绍未知向量，管理方程是在一阶的平常的微分方程的集合的reformulated。用变量的分离，在symplectic空格的eigensolutions被获得。未知向量的一个准确答案以symplectic被获得并且表示eigensolutions。奇特机械，电，并且磁场与概括紧张因素被评估。比较被做验证建议方法的精确性和稳定性。包括混合边界条件的数字例子被给。

简介：PLAispresentlyconsideredasthemostattractivecompoundfortemporarytherapeuticapplicationinthebiomedicalfield.Inthispaperwegiveanoverviewofthepresentknowledgeonthedegradationbehavior,processingtechnologyofPLAanditsapplicationinthefixationofbonefracture.

简介：ThispaperstudiesRabinovitch'scompressionexperimentsongraniteandchalkandproposesanoscillatingdipolemodeltoanalyseandsimulatetheelectromagneticradiationphenomenoncausedbyfractureofrocks.Ourmodelassumesthattheelectromagneticradiationpulsesareinitiatedbyvibrationsofthechargedrockgrainsonthetipsofthecrack.Thevibrationsoftherockgrainsarestimulatedbythepulsesofthecracks.OursimulationsshowcomparableresultswithRabinovitch'scompressionexperiments.Fromthesimulationresults,itverifiesanassumptionthatthecrackwidthisinverselyproportionaltothecircularfrequencyelectromagneticradiation,whichispresentedbyRabinovitchetal.Thesimulationresultsalsoimplythat,byusingouroscillatingdipolemodeltogetherwithRabinovitch'stwoequationsaboutthecracklengthandcrackwidth,wecanquantitativelyanalyseandsimulatetheelectromagneticradiationphenomenon,whichisinducedfromthefractureoftherocks.

简介：模型我伪静电干扰铝泡沫的非线性的骨折被考虑显微镜的异质的效果分析。第一，连续统组成的模型被收养说明金属性的泡沫的塑料压缩的可能性。二参数的Weibull类型功能建模的收益紧张在组成的模型被采用。然后，一个修改连贯的地区模型被建立在起始的裂缝前与一个连贯的地区描绘铝泡沫的破裂行为。张力的拖拉对本地裂缝开始排水量关系被采用描述材料的弄软的特征。并且为衔接破裂过程地区被用于考虑铝的显微镜的异质的在内的应力的山峰的一个Weibull统计模型起泡沫。最后，压力紧张的曲线上的随机的参数的影响被给。数字例子被给说明在这篇论文介绍的数字模型，J积分上的Weibull参数和材料性质的效果被讨论。

简介：Usingultrasonicguidedwavestoassesslongbonefracturesandfracturehealinghasbecomeapromisingdiagnosticissue.Butthemultimodeoverlapoftheguidedwaveschallengesthequantitativeevaluationandclinicalapplication.Inthepreformedstudy,inordertosimplifythesignalinterpretation,thelow-frequencysinusoidialsignalswereusedtoonlyexciteS0andA0modesinfracturedlongbones.TheamplitudesofS0andA0modeswerenumericallyanalyzedwithvariationincrackwidthandfractureangle.Numericalsimulation,basedonthetwo-dimensionfinite-differencetime-domain(2D-FDTD)revealsthatbothS0andA0amplitudesdecreasewiththefracturewidening.However,theincreaseinfractureanglegraduallyenhancestheA0amplitude,whilewithrespecttotheS0mode,itsamplitudeshowsanon-monotonictrendtothevariationinfractureanglewithaturningpointaround45°.TheamplituderatiobetweenS0andA0canreflectthevariationsincrackwidthandfractureangles.ThesimulationillustratesthatultrasonicguidedS0andA0modesaresensitivetothedegreeofbothverticalandobliquefracturesinthelongcorticalbone.Thesefindingsmaybehelpfulforfracturesdiagnosisandhealingevaluationofthelongbone.

简介：Bymeansofreasonableassumptionandmathematicalderivation,atheoreticexpressionofflowrateforasinglefracturewithlinearlyvaryingwidthwasobtained.Themathematicalderivationwasbasedonthecubiclawandthenewtheoreticexpressionwasanextentionoftraditionalparallelplatemodel.Thisstudymayhelptoanalyzeseepageinfracturedrockmass.

简介：吸收材料(静态存储器)的一架新奇结构的雷达，给正常树脂底composites新功能，被准备。静态存储器的动态压缩测试借助于裂口Hopkinson压力酒吧(SHPB)在在里面飞机和composites的正常方向被执行。在沿着在里面飞机方向的压缩测试，失败发生在在纤维和矩阵之间的接口。一个破裂模式和机制被建议解释这些结果。吸收粒子的增加导致压缩性质的恶化。然而，有吸收性质的雷达的静态存储器的压缩力量上没有明显的减少。

简介：Hydrogenembrittlementisoneofthekeyissuesforthevanadiumalloysforfusionapplication.PreviousstudyhasshownthatV4TialloyhadbetterpropertiesagainsttheembrittlementthanV4Cr4TiandV4Ti3A1alloys.Itwasthoughtthatthebetterpropertywasbenefitedfromthesmallratioofitsyieldstrengthoveritsultimatetensilestrength.

简介：Thisstudyconcernsatwo-dimensionalmodelandthecorrespondingvirtualcrackclosuretechnique(VCCT)implementedtosolvethegeneralboundaryvalueproblemsthatmayexplainwhyinterfacediscontinuityhaseffectsonthefracturebehaviorinthesuperconductor-substratesystem.Theinterfacialdiscontinuitycanbeclassifiedaccordingtothematerialproperties'continuityandtheirderivatives'continuityattheinterface.Fornonhomogeneoussuperconductorandsubstratespecimenswithvariousmaterialproperties,aVCCTmethodisdevelopedtocalculatetheirfracturebehavior.Furthermore,theeffectsofappliedmagneticfieldamplitudeandnonhomogeneousparametersareextensivelyandparametricallystudiedintwoactivationprocesses(zero-fieldcoolingandfieldcooling).Theintegrativeandcomputationalstudypresentedhereprovideafundamentalmechanisticunderstandingofthefracturemechanisminthesuperconductor-substratesystemandshedslightontherationaldesignofinterfacialcontinuity.

简介：Jep积分为描绘有弹性塑料的材料的破裂行为被导出。Jep积分不同于米饭J积分因为工作的免费精力密度而非压力密度被采用定义精力动量张肌。Jep积分被证明不管增长粘性和变丑粘性是路径依赖者。Jep积分拥有清楚地清楚的物理意思：(1)在包围裂缝尖端的无穷地小的轮廓上评估的价值Jtipep代表裂缝尖端精力驱散；(2)当全球steadystate裂缝生长条件被接近时，沿着边界轮廓计算的Jfar-ssep的价值等于到裂缝尖端驱散和塑料地区的体积驱散的和。理论结果被模仿我击碎的模式验证问题。

简介：破裂和劈开实验的一个特征是他们通常是内在地破坏的。裂缝完全不在一个不着重的系统愈合，甚至在象云母那样的晶体。这里，我们使用了为非破坏性的劈开和易碎的破裂实验由磁性的脱衣组成的磁性的固体。在磁性的脱衣之间，有不同机械特征的材料能被插入，例如特氟隆重或泡沫脱衣，到变化固体的机械性质。为劈开实验，我们开发了象主要深奥力量那样的参数能容易被测量的一台仪器。由插入缺陷，磁性的固体能在动态破裂实验被使用，与肉眼可见地模仿以一个更容易的方法的一个非破坏性的实验的优点，与高得多的速度发生在真实材料。仪器和使用的磁性的固体可能为在班上的破裂的示范是有用的。