雨课堂学堂在线学堂云《Engineering Mechanics（中国石油大学（华东））》单元测试考核答案

第1题Thestrength,stiffnessandstabilityofthecomponentarerelatedtothemechanicalpropertiesofthematerialaswellastheshapeandsizeofit.

第1题Accordingtothetwo-forcebalanceprinciple,twoforcesshouldsatisfytheconditions,pointingoutthatoneofthefollowingstatementsiswrong.AIt'sactingonthesamerigidbodyBActionisequaltoreaction,butitactsinacontrarydirectionCAlongthesamelineDThetwoforcesareactionandreaction第2题Theprojectionofaforcealonganaxisandthecomponentofaforcealonganaxis().ABotharevectorsBBotharegenerationquantitiesCProjectionisthenumberofgenerations,andthecomponentforceisthevector.DProjectionisthevector,andthecomponentforceisthenumberofgenerations0.3Introduction3第1题Stiffnessreferstothecapacityofthememberto().AResistancemovement

BResistancetodestructionCResistancetodeteriorationDResistancetodeformation第2题Thethreeelementsthatdeterminetheeffectofaforceonanobjectdonotinclude().AThemagnitudeoftheforceBDirectionofforce

CUnitofforceDActionpointofforce第3题Themomentistheproductofthemagnitudeoftheforceand().AdistanceBlengthCArmofforceDCouplearm0.4Introduction4第1题Thecorrectnumberinthefourcellsshowninthefigureis

().(Theunitofstressinthefigureis

MPa)fontABCD1.1.1FundamentalKnowledgeonStatics第1题Therelationshipbetweenforceandobjectiscorrect().AForcescannotexistindependentlyofobjectsBIngeneral,theforcecannotexistindependentlyfromtheobjectCForcescanbedetachedfromobjects第2题Theelementsthatdeterminetheeffectofforceonanobjectare().AThemagnitudeoftheforceBDirectionofforceCActionpointofforceDTheabovethreeitems第3题Theapplicablescopeofforcebalanceconditionis()AdeformablebodyBtherigidbodysystemCrigidbodyDAnyobjectorsystemofthings1.1.2AxiomsinStatics第1题Inthetwo-forcebalanceaxiom,thereare()objectsinteractingwitheachother.A

OneBTwoCThreeDFour第2题Aslongasahorizontalforceisappliedtoanobjectplacedonahorizontalplane,theobjectwillnotstandstill.第3题Inthetwoforcebalanceaxiom,thereare()objectsinteractingwitheachother.A1B2C3D4第4题Thebalanceofanobjectreferstoitsstaterelativetotheearth().AKeepstillBMoveinastraightlineataconstantspeedCAlloftheabovearetrue第5题thetranslationoftheforcemustbeappliedtotheforceatapointontherigidbody().Aparalleltoanypoint

BarbitrarytoanypointCMovetoanypointalongthelineofactionoftheforceDMoveparalleltoanypointalongthelineofactionoftheforce第6题Intheforceparallelogramshownhere,thegraphofthecombined

forcesandis（

）.Afigure（a）Bfigure（b）Cfigure（c）Dfigure（d）1.1.3Momentofaforce第1题Theprojectionofthemomentofaforceonthepointontheaxismustbeequaltothemomentofforceonthataxis.第2题Coupleandmomentaredifferentconcepts.第3题Twocouplesinthesameplaneareequivalenttoeachotheraslongastheirmomentsareequal.第4题Twoforcesofequalsizemusthaveequalmomentsforanaxle.第5题IftheforceFintersectstheZaxis,thenMz(F)=0.第6题Theconditionthatthemomentisnotzerois().ATheforceisnotzeroBThelineofactionoftheforcedoesnotpassthroughthecenterofmomentCTheforceandarmarenotzero1.2.1Constraintandreactiveforce第1题Thebindingforceonthesmoothfaceoftheobiectactsatthecontactpointinadirectionalongthecommonnormalofthecontactsurface,and().APointattheforceobjectwithconstantforce

BPointatthestressedobject,constantpressureCDerivedfromtheforcebody,constantforceDDeviationfromthebearingbody,constantpressure第2题Thesupportwhichonlyallowsteobjecttomoveinanydiectionanddoesnotrestricttherotationoftheobjectiscalled().AfixedhingesupportBmovablehingesupportCfixedendsupportDSmoothsurface第3题Thecircumference()aroundwhichanobjectactsasarestraintiscalledarestraint.

AOtherForcesBOtherForceSystemsCOtherobjectsDOthermaterials第4题Asshowninthefigure,suspendtheweightfromtheceilingwitharopewhereFTisthetensionoftheropeagainsttheweight,FTˊ.Thetensionofaheavyobjectagainstarope,ofwhichtheactingandreactingforcesare().A

GandFTBFTandFTˊCGandFTˊD

None第5题Thetranslationtheoremofforceisonlyapplicabletoarigidbody,anditcanonlybeappliedtothesamerigidbody.第6题Foracertainobjecttoplayalimitingrolearound(),calledconstraints.AOtherforcesBOtherforcesystemsCOtherobjectsDOthermaterials第7题Thedirectionoftheconstraintisthesameasthedirectionofdisplacementthattheconstraintcanblock().AidenticalBcontraryCuncertainD

irrelevant1.2.2Forceanalysis第1题Therigidbodyisinequilibriumundertheactionofthreeforces,thentheactionlineofthethreeforces().AmustmeetatoneBmustbeparalleltoeachotherCwillallzerosDmustbeinthesameplane第2题Thethree-hingedrigidframeshowninthefigureissubjectedtohorizontalforceP.Therearefourstatementsasfollows,ofwhichthewrongoneis().AACisthetwo-forcebalancebarmemberBACisthetwo-forcebalancebarmemberCThedirectionofthereactionforceRAandRBpointstoCDThedirectionofRApointstoC,andthedirectionofRBisuncertain第3题Accordingtothediagram(excludingtheweightofthebar),theforcediagramofbarABiscorrect().ABCD第4题

Aforcecanonlymakearigidbodymove.第5题Forcecanmakearigidbodymoveandrotate.第6题Forceistheinteractionbetweenobjects,itseffectcanbedividedintoexternaleffectandinternaleffect.1.3.1Couples第1题Thestatementaboutthecoupleandthemomentofthecouple,where()iscorrect.AOnlytwoforceswithequalmagnitude,oppositedirectionsandparallellinesofactionarecalledcouplesBTheforcecoupleproducesbothrotationalandmovingeffectsontherigidbodyCAforcecouplecanbereducedtoaforceandthereforecanbeequivalenttoaforceDThemomentofthecoupleatanypointisequaltothemomentofthecouple1.4.1Reductionofgeneralcolplanarforcesystem第1题Asshowninthefigure,threepointsA,BandConaplanearerespectivelysubjectedtoforceP,ABCisanequilateraltriangle,thenthisforcesystem()AbalanceBbalanceCResultanttorqueis0DResultantforceis01.4.2Equilibriumofgeneralcoplanarforcesystem第1题Onenecessaryandsufficientconditionfortheequilibriumofplaneintercrossingforcesystemsisthattheresultantforceiszeroandtheforcepolygonclosesitself.第2题Theplaneconfluenceforcesystemcansolveatmost()unknowns.AOneBTwoCThreeDFour1.4.3Equilibriumofgeneralcoplanarforcesystem第1题Theintersectiontheoremofthreeforcesequilibriumisthe()conditionofcoplanarandnonparallelthreeforcesequilibrium.AsufficientBnecessaryCnecessaryandsufficient1.5.1Equilibriumofrigidbodysystems第1题Theforcecanonlymaketherigidbodymove,andthecouplecanonlymaketherigidbodyrotate.第2题Insolvingtheequilibriumproblem,thedirectionoftheunknownconstraintreactionforceintheforcediagramcanbearbitrarilyassumed.Ifthecalculationresultispositive,thentheassumeddirectionistheactualdirectionoftheforce.第3题Theresultantforce(ifanyresultantforceexists)ofanyforcesysteminspacemustbeequaltotheprincipalvectorobtainedwhentheforcesystemissimplifiedtoanyotherdirection.第4题Theforceisdecomposedalongthespatialcoordinateaxisandtheresultshouldberegardedasanalgebraicquantity.第5题TheprojectionofaspaceforceGontheX-axisandthemomenttakenontheX-axishavethefollowingresults,namelyFx=0,Mx(F)=0,fromwhichitisknownthattheforceisperpendiculartotheX-axisandislocatedontheplanepassingthroughtheX-axis.第6题Thenecessaryandsufficientconditionforbalanceofspaceintersectionforcesystemisthattheresultantforceofforcesystemiszero.第7题Sincethereareonlythreeuniqueequationsforthesystemofintersectionforcesinspace,theproblemofbalanceofthissystemofforcesinspacecanonlybesolvedbythreeunknownquantities.第8题Foragivenarbitraryforcesystem,thepositionoftheprincipalvectorandthesimplifiedcenterisdetermined().ARelevantBirrelevantCuncertain1.6.1Slidingfriction第1题Whenapersonwalks,thedirectionoffrictionbetweenthegroundandthesoleis().AforwardBbackwardCUp第2题TheweightofobjectAisQ,placedonthehorizontalsurface,thestaticslidingfrictioncoefficientf=0.32onthecontactsurface,andwhenahorizontaltensionP=0.3Qisappliedtotheobject,thefrictionFonthecontactsurfaceis().AF=0BF=0.3QCF=0.32QDF=Q第3题Generally,themaximumstaticfrictionishigherthanthedynamicslidingfriction

().ASmallBlarge

CequallyDTwiceasbig1.6.2Equilibriumproblemswithfriction第1题Asshowninthefigure,theweight100NispressedagainsttheverticalwallwithaforceofF=500N,andthefrictioncoefficientf=0.3betweentheobjectandthewallis().

A100NB150NC0Duncertain第2题Whenthebodyisincriticalequilibrium,themagnitudeofstaticfriction().AItisproportionaltothemassoftheobjectBItisproportionaltothegravityoftheobjectinthenormaldirectionofthesupportingsurfaceCItisdirectlyproportionaltothepositivepressurebetweenobjectsincontactDItisdeterminedbytheequilibriumequationoftheforcesystem第3题Themaximumstaticfrictionisproportionaltothevalueof().APositivepressureBgravityCAcomponentofgravity第4题Thewaytoincreasefrictionis().AReducefrictioncoefficientBIncreasefrictioncoefficientCIncreasecontactareaDReducepositivepressure1.6.3Truss第1题Thelineofactionofthetwoforcesactingonthetwobarmustbealongthelineofthetwoactingpoints.1.6.4Spacegeneralforcesystem第1题Iftheforcevectorsaredrawnindifferentorder,theshapeofthefinalforcepolygonwillbedifferent.2.7.1Introduction2第1题Ofthefollowingconclusions,only()istrue.AThetaskofmaterialmechanicsistostudythecompositionofmaterialsBThetaskofmaterialmechanicsistostudythemechanicalpropertiesofvariousmaterialsCThetaskofmechanicsofmaterialsistoprovidethebasictheoryandmethodofanalysisandcalculationfordesigningthestructureofcomponentsundertheprincipleofbothsafetyandeconomyDThetaskofmaterialmechanicsistodesignthestructureofthecomponentundertheprincipleofensuringsafety2.7.2Introduction3第1题Thesafetyfactorofplasticmaterialingeneralmachinerymanufactureatpresent（

）safetyfactorofgeneralbrittlematerials.AlessthanBgreaterthanCequaltoDcannotcompare2.7.3Introduction1第1题

()aretwobasicphysicalquantitiesinmechanicsATorqueandCoupleTorqueB

ForceandcoupleCMassandweightDForcesandtorques2.7.4Introduction4第1题Withregardtothegeneralmechanicalpropertiesofmaterials,pleasedecidewhichoneiscorrect().AThetensilestrengthofAbrittlematerialislowerthanitscompressivestrengthBThetensilestrengthofabrittlematerialishigherthanitscompressivestrengthCThetensilestrengthofaplasticmaterialishigherthanitscompressivestrengthDThetensilestrengthofabrittlematerialisequaltoitscompressivestrength2.8.1Internalforcesofaxiallyloadedmembers第1题Thesectionmethodisgenerallyapplicabletouniformandvariablesectionbars(straightandcurved),elasticandplasticdeformation,basicdeformationandcombineddeformation.2.8.2Internalforcesofaxiallyloadedmembers第1题Thereisonlynormalstressandnoshearstressinthememberunderaxialtension(compression).第2题Whenthelowcarbonsteelspecimensyieldintension,asliplineabout45°directionwiththeaxisappearsonthesurface,whichisrelatedtothemaximumshearstress2.8.3Deformationofarodintensionorcompression第1题Thetwoendsofastraightbarareactedonbyapairofforcesequalinvalueandoppositeinthelongitudinalplaneofsymmetry,andthestraightbarwillproduce(

).AtensionandcompressiondeformationBsheardeformationCbendingdeflectionDtorsionaldeformation2.8.4Mechanicalpropertiesofmaterials（1）第1题Forbrittlematerial,plasticyieldfailurewillnotoccur.

第2题Ifthestressinacertaindirectioniszero,thestraininthatdirectionmustbezero.2.8.5Mechanicalpropertiesofmaterials（2）第1题Theultimatestressasabrittlematerialis().AElasticlimitBYieldlimitCStrengthlimitDProportionalLimit

第2题Theelongationoftheplasticmaterialshall().A<5%B=5%

CThereisnofixedstandardD>5%2.9.1TorsionExternalcouplemoment，internaltorqueandinternaltorquediagram第1题Thehigherthespeedoftheshaft,thegreaterthetorqueonthecrosssectionoftheshaft.

2.9.2TorsionCirculartubeintorsion第1题Whenthecircularaxisistorsional,theshearstressonthesamecircumference().AExactlythesameBcompletelydifferentCpartsofthesameDUnabletodetermine2.9.3TorsionStressofCircularShaft（I）第1题Whenonecircularaxisistwisting,therearebothnormalstressandshearstressonthecrosssection.第2题Whentheconstantsectionstraightbaristwisted,thecrosssectionofthebarremainsflatafterdeformation,anditsshapeandsizeremainunchanged.第3题Theresultsshowthatthecastironroundbarwillfractureatthemaximumtensilestresssurfacewhenitisundertorsionandaxialtension第4题Thecrosssectionandthelongitudinalsectionofacircularrodremainplanewhenitistwisted2.9.4TorsionStressofCircularShaft（II）第1题Ifthediameterofthesecondshaftistwicethatofthefirstshaftunderthesametorqueactionoftwocircularshaftsofthesamelength,thentheratioofthemaximumshearstressbetweenthefirstshaftandthesecondshaftis().A2:1B4:1C8:1D16:12.9.5StrengthenConditionofCircularShaftinTorsion第1题Theinnerandouterdiametresofthehollowcircularaxisaredandd,andtheratiooftheinnerandouterdiametresisd/D=α.Thecorrectexpressionsforthepolarmomentofinertiaandthetorsionalsectioncoefficientofthecrosssectionshouldbe（）AIp=πD4/64(1-α4),WP=πD3/32(1-α3)BIp=πD4/32(1-α4),WP=πD3/16(1-α3)CIp=π/32（D4-α4）,WP=π/16(D3-α3)DIp=πD4/32(1-α4),WP=πD3/16(1-α4)2.9.6DeformationandStiffnessConditionofCircularShaft第1题Castironroundrodswillfractureatthesurfaceofmaximumtensilestressinbothtorsionandaxialtension.2.10.1Shearstressandstrain第1题WhentheshearforceofasectionFQ=0().AThereisAsuddenchangeinbendingmomentonthissectionBThebendingmomentonthissectionhasanextremevalueCThebendingmomentonthissectionmustbethemaximumofthebeamD

Thebendingmomentonthissectionmustbezero2.10.2Practicalcalculationofbearing第1题Thecompressionstrengthoftheboltcanbeimprovedbyplacingawasherbetweentheplateandthetensionboltasshowninthefigure.第2题Thehingeconnectionoftwopartswithcylindricalpincannotonlylimittherelativemovementoftwoparts,butalsolimittherelativetransmissionoftwoparts.2.11.1Bendingbeamintroduction1第1题Thebasicformsofstationarybeamsare().ASimplesupportedbeam

BExtendingbeamCcantileverbeamDTheabovethreeitems第2题Inplanebending,theexternalforces(orcouples)actingonthebeam().AOnaxis

B

LongitudinalsymmetryinplaneCInsideShaftFace

2.11.2Internalforcesofbeamshearforceandbendingmoment第1题Forbeam’sdeformation,theangleofrotationisthelargestwherethebendingmomentisthelargest,andtheangleofrotationisalsozerowherethebendingmomentiszero.

2.11.3ForceandBendingMomentEquationsShearforceandbendingmomentDiagram第1题Theinternalforcesoftherodsinastaticallyindeterminatestructuredonotcausedeformation.2.11.4ShearForceandBendingMomentEquationsShearforceandbendingmomentDiagram4第1题Theultimatestressofplasticmaterialsisgenerally（）.AyieldlimitBultimatestrengthCproportionallimit

Delasticlimit2.11.5Relationsamongloadshearforceandbendingmoment第1题Forbeam’sdeformation,apositivemomentwillproduceapositiveangleofrotationandanegativemomentwillproduceanegativeangleofrotation.

第2题Thecrosssectionwiththelargestbendingmomentonthebeamhasthelargestdeflection,andwherethebendingmomentiszero,theangleofrotationiszero.第3题Themaximumbendingmomentmustoccuratthecrosssectionwithzeroshearforce.2.12.1PropertiesofPlaneArea-1第1题Themomentofforcecoupleism,andthediameterisDaccordingtothestrengthcondition.Whentheexternalforcecouplemomentincreasesto2m,thediametershouldincreaseto()A1.89B1.26C1.414D22.12.2Propertiesofplanearea-2第1题Forhollowandsolidcircularshaftswiththesamematerialandcross-sectionalarea,thetorsionalstiffnessoftheformermustbethesameasthatofthelatter.AlessthanBequaltoCgreaterthanDcan'tcompare2.13.1Stressofpurebending-1第1题

Incaseofpurebendingofthebeam,theinternalforceonthesectionis()Abendingmoment

BtorqueCshearforceDAxialforceEshearingforceandbendingmoment第2题Whenaplaneisbending,theneutralaxisisperpendiculartotheloadingsurface.第3题Forpurebending,theaxisofthebeamafterdeformationisacirculararc.第4题Inplanebending,theneutralaxisisperpendiculartotheloadingsurface.2.13.2Normalstressofpurebending-2第1题ForcastironbeamswithTsection,themaximumtensilestressalwaysoccursatthecrosssectionwiththemaximumpositivebendingmoment.

2.13.3Normalstressofbeaminpurebending第1题Forpurebending,hecrosssectionremainsflatafterdeformation,anditsshapeandsizewillnotchange.

第2题Accordingtotheequation,thebendingmomentMisaconstantiftheshearstress

ofonebeam’scrosssectionmeets.

2.13.4Shearstressinbending4第1题IfonlyoneconcentratedforceF

isappliedonthesimplebeam,thenthemaximumshearstressofthebeamsatisfies

andthemaximumbendingmomentofthatbeamsatisfies

wherel

beingthelengthofthebeam.

2.13.5StrengthProblemsofBeam5第1题Theouterdiameterofahollowsteelshaftandasolidaluminumshaftisthesame.Bycomparingthetorsionalsectioncoefficientofthetwo,wecanknow（

）AhollowsteelshaftislargerBthesolidaluminumshaftislargerCit'sthesamevalueDitsmagnitudeisrelatedtotheshearmodulusoftheshaft3.14.1Basicconceptsofbendingdeformation第1题Whenabeamisbentinaplane,itscrosssectionrotatesabout().AAxisofbeamBThelongitudinalaxisofsymmetryinacrosssectionCLineofintersectionbetweentheneutrallayerandthelongitudinalplaneofsymmetryDtheneutralaxis3.14.2Approximatedifferentialequationofdeflectioncurve第1题Themaximumnormalstressinbendingofthebeamis().ANeutralshaft

BOntheaxisofsymmetryCOntheedgefurthestfromtheneutralaxis3.14.3Calculationofbeamdeformationbyintegralmethod第1题Whentheloadonthebeamisonlyconcentrated,thebendingmomentisshownas().AHorizontalLineBCurveCObliqueLine3.14.4Calculationofbendingdeformationbysuperpositionmethod第1题Whenabeamissubjectedtoseveralforcesatthesametime,thedeflectionandangleofrotationofonecrosssectionareequaltothealgebraicsumofthedeflectionandangleofrotationofthatcrosssectionundereachforce.

3.14.5Stiffnessofabeam第1题Inthefollowingfourcases,()iscalledpurebending.ATheloadisactedonthelongitudinalsymmetryplaneofthebeamBOnlybendingoccursinthebeam,withouttorsionandtensiondeformationCWhentheplaneisbent,thereisonlybendingmomentbutnoshearforceoneachsectionofthebeamDWhentheplaneisbent,therearebendingmomentsandshearingforcesoneachsectionofthebeam3.14.6StaticallyIndeterminateBeams第1题Tosolvethestaticallyindeterminatestructure,itisnecessarytoestablishthedeformationcoordinationequation,thatis,thegeometricrelationshipbetweenthedeformationsofeachbar.

3.15.1Abriefintroductiontothestressstate1第1题IntheInternationalSystemofUnits,thebasicunitofstressis().

APa［帕］Bkg［千克］

CkN［千牛］DN［牛顿］第2题Thereisnoyieldorneckingphenomenoninbrittlematerialspecimensduringtension.第3题Thesuperpositionofonetwo-dimensionalstressstateandanothertwo-dimensionalstressstateresultsintwo-dimensionalstressstate.3.15.2Descriptionofthestressstateatonepoint2第1题

Onebidirectionalstressstateissuperimposedonanotherbidirectionalstressstate,andtheresultisstillabidirectionalstressstate.

3.15.3Stressanalysisinanarbitraryinclinedcrosssection3第1题Thetaskofstudyingthestateofstressatapointis().AUnderstandthestressvariationatdifferentsectionsBUnderstandthechangeofstressonasectionwithexternalforceCThetensilestrengthofaplasticmaterialishigherthanitscompressivestrengthDFindoutthestresschangeruleofapointatdifferentazimuthsection3.15.4Principalstress,principalsurfaceandmaximumshearingstress4第1题Theactingsurfaceofthemaximumorminimumnormalstressmustbethemainplane.第2题Intheelement,theremustbenonormalstressintheplanewherethemaximumshearstressresides.第3题Theactionsurfaceofthemaximumorminimumnormalstressmustbetheprincipalplane第4题Intheelementbody,theremustbenonormalstressintheplaneofthemaximumshearstress3.15.5Mainreasonsforthecollapseofmaterials5第1题Whenthetensilelowcarbonsteelspecimenyields,asliplineappearsonitssurfaceinthedirectionofabout45°withtheaxis,whichisrelatedtothemaximumshearstress.3.15.6Analysisoftheplanarstressstate-graphicmethod第1题Regardingthestress,()iscorrectinthefollowingconclusion.AStressisdividedintonormalstressandshearstress.BStressistheaveragevalueofinternalforces.C

Thenormalstressateachpointonthesamesectionisthesame.D

Thedirectionofshearstressateachpointonthesamesectionisthesame.3.15.7Stress-strainrelationinthecomplexstressstate第1题Ifthestressofthebarinacertaindirectioniszero,thenthestraininthatdirectionmustalsobezero.

第2题Theaxialforce,cross-sectionalareaandlengthofthetworodsareallthesame,butthematerialisdifferent,sothestressonthecross-sectionofthetworodsisthesameandthestrainisdifferent.第3题Thenormalstressesonthetwomutuallyperpendicularsectionsofthetwo-directionstressstateelementbodyhavethesamemagnitudeandoppositesign.

3.15.8Criterionofstrength第1题Accordingtothesecondstrengththeory,cast-ironcomponentsaresaferinbiaxialstretchthaninuniaxialstretch.3.15.9Applicationexamplesofthetheoryofstrength第1题

Nomatterwhichstateofstressaplasticmaterialisin,thethirdorfourththeoryofstrengthshouldbeappliedinsteadofthefirstorsecondtheoryofstrength.第2题Theresultsshowthatthefractureofcastironisalongthecrosssectionduringtensiletest().ATorsionfailure

BTensilefailure

CShearfailure

DCrushingfailure第3题Theresultsshowthatthelowcarbonsteelspecimensfracturealongthecrosssectionintorsion().ATorsionfailure

BTensilefailure

CShearfailureDCrushingfailure第4题Whenthecastironspecimenistwisted,thespiralsurfacewith45°angletotheaxiswillfracture().ATorsionfailure

BTensilefailure

CShearfailure

DCrushingfailure第5题Thereasonforfailureoflowcarbonsteelspecimeninuniaxialtensiletestisthat().ATorsionfailure

BTensilefailureCShearfailureDCrushingfailure第6题Thereasonforthefailureofcastironspecimeninuniaxialcompressiontestisthat().ATorsionfailure

BTensilefailure

CShearfailureDCrushingfailure第7题Thesumofthenormalstressesonthetwomutuallyperpendicularsectionsoftheelementbodyinthetwo-dimensionalstressstateisconstant第8题Theequivalentandinversesignofshearstressontwomutuallyperpendicularsectionsofelementbodyintwo-dimensionalstressstate.第9题Thefailureofplasticmaterialmustbecausedbyplasticyielding第10题Thethreeprincipalstressesontheelementare50MPa,0and-50MParespectively.Thevalueoftheequivalentstressofthethirdstrengththeoryis().A100MPaB0MPa

C50MPaD-50MPa第11题Thethreeprincipalstressesontheelementbodyare60MPa,10MPaand-50MParespectively,andthemaximumshearstressoftheelementis().A55MPa

B0MPaC60MPaD50MPa

3.16.1Compositedeformation1第1题Thereisnormalstressbutnoshearstressintheaxialtension(compression)specimen.3.16.2Compositedeformation2第1题Thesectionmethodisgenerallyapplicabletobarswithconstantandvariablesections(straightandcurved),elasticandplasticdeformation,basicdeformationandcombineddeformation第2题Eccentricstretchingisacombineddeformationofstretchingandbending.第3题Thecircularcross-sectionrod()isobliquelybent.Aimpossible

BcertainCuncertain

第4题Theforcecharacteristicofobliquebendingdeformationisthattheactinglineofexternalforcepassesthroughthecentroidofthesection,butdoesnotcoincidewiththeaxisofsymmetryofthesection.3.16.3Compositedeformation3第1题Forconstantsectionbeam,themaximumnormalstress

mustappearatthecrosssectionwhichhasthem