英文弹性力学课件.ppt

文档介绍：,thestateofstressatapointwithreferencetothegeneralCartesianco-ordinatesystemisnotverysignificant. Becauseofthat: -ordinateaxes. Therefore,,txy,txzbestressesonplaneOBCLetsy,tyx,tyzbestressesonplaneOACLetsz,tzx,tzybestressesonplaneOABandsnx,sny,snzbestressesonplaneABC()wheredAistheareaofABCDividingEq.()bydA,():.26)()Eq.(),considerasetofaxesx',y',z'.Letx':gthesedirectioncosines,()Substitutingforsnx,snyandsnzfromEq.()()Similarly,()or()and():sx=800kPa,sy=1200kPa,sz=-400kPa,txy=400kPa,tyz=-600kPaandtzx=(a)thestressesonaplanewhosenormalhasdirectioncosinesl1=1/4andl2=1/2,and(b):therelation:get:;fromEq.()::toaxesx’y’z’forstresses:ponentsandthedirectioncosinesas: