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

简介：Basedonshearlagmodelofinterfacebetweenfiberandmatrix,anewformulathatre-latesthecrackopeningdisplacementandbridgingforceinfibrousmonolithicceramicswasconstructedundertheframeworkofsmallscalebridging.Thisformulawasappliedtopredictthefractureresis-tanceorR-curveresponseofathree-pointbendingspecimenmadeoffibrousmonolithicceramics.Aparametricinvestigationontheinfluencesoffibervolumefraction,fiberradius,characteristicsofconstituents,BN’sfracturetoughnessandspecimen’sgeometryonthebridgingforcesandfracturere-sistanceinSi3N4/BNcompositewascarriedout.TheupperandlowerlimitsoftheR-curveofSi3N4/BNinsmallscalebridgingwerederived,Thisresearchrevealedtheroleplayedbytheaboveparame-tersinthefracturetoughnessoffibrousmonolithicceramics.

简介：M积分的物理解释在损坏裂缝的压电的问题的分析被调查。在M积分和全部的电的热含量(CTEE)的变化之间的关系，即，M=2CTEE，为二维的压电的问题与一个理论推导过程被导出。M积分可以由于与损坏身体，而非对为常规易碎的固体解释了的全部的势能版本率的描述联系的pre-existingmicroc-racks的形成提供对电的热含量版本的更自然的描述，这被显示出。为损坏裂缝的压电的陶艺，M积分的数字计算被讨论。基于pseudo-tractionelectric排水量方法，M=2CTEE被数字结果也证明了。