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《Local and global energy release rates for an electrically yielded crack in a piezoelectric ceramic》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、J.Mech.Phys.Solids.Vol.45,No.4,pp.491-510,199701997ElsevierScienceLtdPergamonPrintedinGreatBritain.Allrightsreserved002225096/97$17.00+0.00PII:SOO22-5096(96)OOlOt3-1LOCALANDGLOBALENERGYRELEASERATESFORANELECTRICALLYYIELDEDCRACKINAPIEZOELECTRICCERAMICHUAJIANGAO,?TONG-Y1ZHANGfandPINTONG1tDivision
2、ofAppliedMechanics,StanfordUniversity,Stanford,CA94305,U.S.A.andfDepartmentofMechanicalEngineering,CenterforAdvancedEngineeringMaterials,HongKongUniversityofScienceandTechnology,ClearWaterBay,Kowloon,HongKong(Received18July1996;inrevised,form2October1996)ABSTRACTStructuralreliabilityconcernsof
3、variouselectromechanicaldevicescallforabetterunderstandingofthemechanismsoffractureinpiezoelectricceramicssubjectedtocombinedmechanicalandelectricalloading.Forthesematerials,duetounexplaineddiscrepanciesbetweentheoryandexperiments,eventhebasiccriterionoffractureremainsapointofcontroversy.Aview
4、pointadoptedinthispaperistomodelpiezoelectricceramicsasaclassofmechanicallybrittleandelectricallyductilesolids.Asafirststeptowardunderstandingtheeffectsofelectricyielding,astripsaturationmodelisdevelopedforafinitecrackperpendicularorparalleltothepolingaxisofaninfinitepoledpiezoelectricceramics
5、mediumwithelectricalpolarizationreachingasaturationlimitalongalinesegmentinfrontofthecrack.ThismodelmaybeconsideredasageneralizationoftheclassicalDugdalemodelforplasticyieldingnearcracksinthinmetalsheets.Theessentialfeaturesofthestripsaturationmodelareanalyzedviaasimplifiedelectroelasticityfor
6、mulation.Twoenergyreleaseratesemergefromthisanalysis.AnapparentorglobalenergyreleaserateappearswhenevaluatingJ-integralalongacontoursurroundingboththeelectricalyieldingstripandthecracktip.Undersmallscaleyieldingconditions,thisenergyreleaserateisequaltothatofalinearpiezoelectriccrackwithoutelec
7、tricalyielding.AlocalenergyreleaserateisobtainedbyevaluatingJalonganinfinitesimalcontournearthecracktip.Thelocalenergyreleaserategivespredictionswhichseemtobeinbroadagreementwithexperimentalobservations.Itisalsointerestingthatthelocalen
