简介:Mechanisminteractionbetweencrackswithdifferentorientationanglesisanalyzedbasedontheprincipleofsuperpositionandaflatteningmethod.Itisfoundthatthemaximuminteractioneffectdoesnotoccurwhenthemicrocrackisalongthedirectionparallelorperpendiculartotheprincipaltensilestress,whichisdifferentfromtheconclusiondrawnbyOrtiz(1987).Themechanismofmicrocrackgenerationandtheeffectofthemicrocrackzoneonthemaincracktiparestudied.Itisconcludedthatthemicrocrackzonehaseffectonthemaincracktip,whichincreaseswiththeincreaseofmicrocrackdensityandlength.
简介:Forafinitebeamwithanonzerogapdistance,anasymmetricconcentratedloadcanbeeitherinsideoroutsideofthecontactzone.Anewgoverningequationisgivenforthecaseofaconcentratedloadoutsidethecontactzone.Bynumericallysolvingtheleft-sideandright-sidecontactlengthsofthebeam,acriterionisestablishedtodeterminewhethertheconcentratedloadisinsideoroutsidethecontactzone.Amoregeneralapproachonthetensionlesscontactofabeamisthuspresented.
简介:Atheoreticalmodelthattakesintoaccountthefree-volumeaidedcooperativeshearingofsheartransformationzones(STZs)isdevelopedtoquantitativelyunderstandtheductile-to-brittletransition(DBT)ofmetallicglasses.TheSTZdilatationalstrainisdefinedastheratioofSTZ-activatedfreevolumetoSTZvolumeitself.ThemodeldemonstratesthattheSTZdilatationalstrainwillincreasedrasticallyandexceedthecharacteristicshearstrainofSTZastemperaturedecreasesbelowacriticalvalue.ThiscriticaltemperatureisingoodagreementwiththeexperimentallymeasuredDBTtemperature.OurresultssuggestthattheDBTofmetallicglassesisunderpinnedbythetransitionofatomic-clustermotionsfromSTZ-typerearrangementstodilatationalprocesses(termedtensiontransformationzones(TTZs)).