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1、兰大《工程力学(II)(材料)》13春在线作业1（Engineeringmechanics(II)(material)13springonlineassignment1）Spring13,autumn,theengineeringmechanics(II)(material)13springonlinehomework1Totalscore:100testtime:--SingletopicselectionMultiplechoiceTrueorfalse(atotalof10questions,40points.)1.Therearetwotheories:(
2、1)ifthemaximumtensilestressofacertainpointintheplasticmaterialisMax=sigma,thenthepointmustyield;(2)ifthemaximumtensilestressofacertainpointinbrittlematerialisMax=sigmab,thepointmustberuptured.Accordingtothefirstandfourthstrengththeory,thetheorycanbeknown.A.(1)incorrect,(2)correct(1)co
3、rrect,(2)incorrectC.(1)and(2)arecorrectD.(1)and(2)arenotcorrectFullmarks:4points2.Therearefouranswerstothemainfeaturesofobliquebending,andtrytodeterminewhichoneiscorrect().A.Mydoesnotequal0,Mzdoesnotequal0,FNxdoesnotequal0B.Theneutralaxisisinconsistentwiththecentroidaxisanddoesnotpass
4、throughthecrosssectionC.Mydoesnotequal0,Mzdoesnotequal0,FNx=0,theneutralaxisisinconsistentwiththecrosssectionaxis,butthroughthecrosssectionD.Mydoesnotequal0,Mzdoesnotequal0,FNx=0,theneutralaxisisparalleltothecentralaxisofthecrosssection,butnotthroughthecrosssectionE.Mydoesnotequal0,Mz
5、doesnotequal0,FNxdoesnotequal0,theneutralaxisisparalleltothecrosssectioncenteraxis,butnotthroughthecrosssectionFullmarks:4points3.Internalforceinmaterialmechanicsrefersto()A.TheforceinsidetheobjectB.TheinteractionbetweenthemasspointsinsidetheobjectC.DeformationcausedbyexternalforcesD.
6、AchangeintheresultantforceoftheinteractionbetweentheparticlesoneachsideofasectioncausedbyanexternalforceFullmarks:4points4.Sectionbendingmomentofconcentratedforce().A.greaterthanzeroB.lessthanzeroC.equaltozeroD.notsureFullmarks:4pointsSheardamageoccurson().A.ShearmemberB.Objectsaround
7、theshearmemberC.thestrengthoftheshearcomponentandsurroundingobjectsisweakerFullmarks:4points6.Atoneend,therectangularcross-sectionofthefreerectangleisfixedatoneend,andb/h=1/2.Ifthewidthbisdoubledandtheotherconditionsareconstant,thecriticalpressureistheoriginal().2timesA.4timesB.C.eigh
8、ttime
