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1、兰大《工程力学(ii)(材料)》13春在线作业214spring13autumnbigorchid"EngineeringMechanics"(II)(material)14spring13autumnbigorchidEngineeringMechanics(II)(material)13springonlinehomework231Totalscore:100testtime:-RadioexaminationAmultiple-choicequestionJudgmentquestionRadioexaminationquestions(10questions,40points
2、)1.astraightrodwithacircularcross-section,thetensionatbothendsofthesame,ifthediameterdoubled,otherconditionsremainunchanged;().A.axialforceremainsunchangedB.stressremainsunchangedC.stiffnessremainsunchangedD.elongationconstantFullmarks:42.,thereisasolidcircularsectionaxis,itsdiameterisD1,andthe
3、otherhollowroundaxisoftheouterdiameterofD2,alpha=0.8,ifthetwoaxiscrosssectiontorqueandmaximumshearstressareequal,thenD1:D2=().A.0.839B.0.59C.0.768D.1.19Fullmarks:43.thestrength,stiffnessandstabilityofthecomponent.A.isonlyconcernedwiththemechanicalpropertiesofmaterialsB.onlydependsontheshapeands
4、izeofthecomponentC.hasnothingtodowiththetwoD.hasnothingtodowiththetwoFullmarks:44.flexibleconstraintscanonlyrestricttheobjecttomovealongaflexibleconstraint().A.elongationdirectionB.shortendirectionC.verticalD.atanyangleFullmarks:4Thestress-straincurvesof5.lowcarbonsteeltensilespecimenscanberoug
5、hlydividedintofourstages.Thesefourstagesare()A.elasticdeformationstage,plasticdeformationstage,yieldstageandfracturestageB.elasticdeformationstage,plasticdeformationstage,strengtheningstageandneckingstageC.elasticdeformationstage,yieldstage,strengtheningstageandfracturestageD.elasticdeformation
6、stage,yieldstage,strengtheningstageandneckingstageFullmarks:46.onthemainplaneoftheunit.A.themaximumnormalstressmustbemaximumB.thenormalstressmustbezeroC.shearstressmustbeminimalD.shearstressmustbezeroFullmarks:47.whenthehollowtubeisaxiallystretched,iftherodisintheelasticrange,thecrosssectionisd
7、eformed.A.diameterandwallthicknessarebothincreasedB.outerdiameterandwallthicknessarebothreducedTheouterdiameterofC.decreasesandthewallthicknessincreasesTheouterdiameterofD.increasesandthewallthicknessdecreasesFullmarks:48.thecondi
