【MOOC】Mechanics of Materials （《材料力学》全英文）-北京理工大学 中国大学慕课MOOC答案

【MOOC】MechanicsofMaterials（《材料力学》全英文）-北京理工大学中国大学慕课MOOC答案HomeworkassignmentsforChapter1ThesmallquizforChapter11、【单选题】Mechanicsofmaterialsisastudyoftherelationshipbetweenthe()appliedtoabodyandthe()and()causedbythe()withinthebody.本题答案：【externalloads,stress,strain,internalloads】2、【单选题】Lineardistributedloadingsproducea()havingamagnitudeequaltothe(),andhavingalocationthatpassesthroughthe().本题答案：【resultantforce,areaundertheloaddiagram,centroidofthisarea】3、【单选题】Asupportproduces()inaparticulardirectiononitsattachedmemberifitprevents()ofthememberinthatdirection,anditproduces()onthememberifitprevents().本题答案：【anexternalforce,translation,anexternalcouplemoment,rotation】4、【单选题】Themethodofsectionsisusedtodeterminethe()actingonthesurfaceofthesectionedbody.Ingeneral,theseresultantsconsistofa(),(),(),andbendingmoment.本题答案：【internalresultantloadings,normalforce,shearforce,torsionalmoment】5、【单选题】Theintensityofthe()atapointinthebodyisreferredtoasstress.Stressisthe()valueofforceperunitarea,astheareaapproaches().Forthisdefinition,thematerialisconsideredtobe()and().本题答案：【internalforce,limiting,zero,continuous,cohesive】6、【单选题】Whenaprismaticbarismadefrom()and()material,andissubjectedtoanaxialforceactingthroughthe()ofthecross-sectionalarea,thenthecenterregionofthebarwilldeform().Asaresult,thematerialwillbesubjectedonlyto().Thisstressis()oraveragedoverthecross-sectionalarea.本题答案：【homogeneous,isotropic,centroid,uniformly,normalstress,uniform】7、【单选题】Whenshearstressactsonaplane,then()ofavolumeelementofmaterialatapointontheplanerequiresassociated()ofthe()actonthreeadjacentsidesoftheelement.本题答案：【equilibrium,shearstress,samemagnitude】8、【单选题】Designofamemberforstrengthisbasedonselectingan()thatwillenableittosafelysupportitsintendedload.Sincetherearemanyunknownfactorsthatcaninfluencetheactualstressinamember,thendependingupontheintendeduseofthemember,()isappliedtoobtainthe()themembercansupport.本题答案：【allowablestress,afactorofsafety,allowableload】HomeworkassignmentforChapter2AsmallquizforChapter21、【单选题】()isameasureperunitlengthoftheelongationorcontractionofasmalllinesegmentinthebody,whereas()isameasureofthechangein()thatoccursbetweentwosmalllinesegmentsthatareoriginally()tooneanother.本题答案：【Normalstrain,shearstrain,angle,perpendicular】2、【单选题】Thestateofstrainatapointischaracterizedby()straincomponents:()normalstrainsand()shearstrains.Thesecomponentsdependupontheoriginal()ofthelinesegmentsandtheir()inthebody.本题答案：【six,three,three,orientation,location】3、【单选题】本题答案：【0.00116mm/mm】4、【单选题】Theslenderrodshowninthegivenfigureissubjectedtoanincreaseoftemperaturealongitsaxis,whichcreatesanormalstrainintherodofwherezismeasuredinmeters.ThedisplacementoftheendBoftherodduetothetemperatureincreaseis()andtheaveragenormalstrainintherodis().本题答案：【2.39mm(downward),0.0119mm/mm】5、【单选题】TherigidbeamissupportedbyapinatAandwiresBDandCE.IfthedistributedloadcausestheendCtobedisplaced20mmdownward,thenormalstraindevelopedinwiresDBis()andinwireCEis().本题答案：【0.00533mm/mm,0.01mm/mm】HomeworkassignmentsgiveninthetextbookforChapter3AsmallquizforChapter31、【单选题】Thepointof()onthestress-straindiagramrepresentstheproportionallimitandtheultimatestress.本题答案：【A,D】2、【单选题】Thematerialforthe50-mm-longspecimenhasthestress–straindiagramshown.IfP=100kNmtheelongationofthespecimenis().本题答案：【0.0796mm】3、【单选题】A100-mmlongrodhasadiameterof15mm.Ifanaxialtensileloadof20kNisappliedtoit,thechangeinitsdiameteris().E=70GPa,=0.35.本题答案：【】4、【单选题】IftheelongationofwireBCis0.3mmaftertheforcePisapplied,themagnitudeofPis().ThewireisA-36steelandhasadiameterof3mm.本题答案：【942N】5、【单选题】A150-mmlongrodhasadiameterof10mm.Ifanaxialtensileloadof150kNisapplied,itschangeoflengthis().E=200GPa.Itisassumedthatmaterialbehaviorislinearelastic.本题答案：【1.4324mm】6、【单选题】A20-mm-diameterbrassrodhasamodulusofelasticityofE=100GPaIfitis4mlongandsubjectedtoanaxialtensileloadof12kN,itselongationis()本题答案：【1.5279mm】7、【单选题】Asolidcircularrodthatis600mmlongand20mmindiameterissubjectedtoanaxialforceofP=50KN.Theelongationoftherodis,anditsdiameterbecomes=19.9837mm.themodulusofelasticityofthematerialis().Assumethatthematerialdoesnotyield.本题答案：【68.2GPa】8、【单选题】A20-mm-wideblockisfirmlybondedtorigidplatesatitstopandbottom.WhentheforcePisappliedtheblockdeformsintotheshapeshownbythedashedline.Theblock'smaterialhasshearmodulusG=52GPa.Assumethatthematerialdoesnotyieldandusesmallangleanalysis.ThemagnitudeofPis().本题答案：【520KN】HomeworkassignmentsgiveninthetextbookforChapter4.1HomeworkassignmentsgiveninthetextbookforChapter4.2AsmallquizforChapter41、【单选题】Saint-Venant'sprinciplestatesthatboththelocalized()whichoccurwithintheregionsofloadaplicationoratthesupportstendtoevenoutatadistancesufficientlyremovedfromtheseregions.本题答案：【deformationandstress】2、【单选题】SinceHooke'shasbeenusedinthedevelopmentofthedisplacementequations,itisimportantthattheloadsdonotcause()ofthematerialandthatthematerialis()andbehavesina()manner本题答案：【yielding;homogeneous;linear-elastic】3、【单选题】Superpositionrequiresthattheloadingbelinearlyrelatedtothe()or(),andtheloadingdoesnotsignificantlychangethe()geometryofthemember.本题答案：【stress;displacement;original】4、【单选题】Amemberisstatically()iftheequationsofequilibriumare()todetermine()onamember.本题答案：【indeterminate;notsufficient;theexternalforces】5、【单选题】()specifythedisplacementconstraintsthatoccuratthe()orotherspointsonamember.本题答案：【Compatibilityconditions;supports】6、【单选题】()occuratsectionswherethecross-secitonalareasuddenly().本题答案：【Stressconcentrations;changes】7、【单选题】AstressconcentrationfactorKcanbedeterminedthroughexperimentandisonlyafunctionofthe()ofthespecimen.本题答案：【geometry】8、【单选题】Thestressconcentrationina()specimenthatissubjecttoastaticloadingwillnothavetobeconsideredindesign;however,ifthematerialis(),orsubjectedto()loadings,thenstressconcentrationsbecomesimportant.本题答案：【ductile;brittle;fatigue】9、【单选题】Thermalstresscanoccurina()withtemperaturevariation.本题答案：【staticallyindeterminatemember】10、【单选题】Thedisplacementofonepointontheaxiallyloadedmemberrelativetotheotherpointisdeterminedby,whichcanbeusedforthe()material.本题答案：【homogeneous,isotrpicandlinear-elastic】11、【单选题】The30-mm-diameterA-36steelrodissubjectedtotheloadingshown.ThedisplacementofendAwithrespecttoendCis().本题答案：【-0.858mm】12、【单选题】The20-mm-diameter2014-T6aluminumrodissubjectedtotheuniformdistributedaxialload.ThedisplacementofendAis().本题答案：【0.882mm】13、【单选题】Thetwopipesaremadeofthesamematerialandareconnectedasshown.Ifthecross-sectionalareaofBCisAandthatofCDis2A,ThereactionsatBandDwhenaforcePisappliedatthejunctionCare().本题答案：【1/3P,-2/3P】14、【单选题】Thethreesuspenderbarsaremadeofthesamematerialandhaveequalcross-sectionalareasA.TheaveragenormalstressinthebarABis()iftherigidbeamACEissubjectedtotheforceP.本题答案：【(7P)/(12A)】15、【单选题】ThewiresABandACaremadeofsteel,andwireADismadeofcopper.Beforethe200lbforceisapplied,ABandACareeach60in.longandADis40in.long.Ifthetemperatureisincreasedby80degreeF.TheforceinthewireACneededtosupporttheloadis().,.,.Eachwirehasacross-sectionalareaof0.0123in.本题答案：【28.86lb】HomeworkassignmentsgiveninthetextbookforChapter5_part1HomeworkassignmentsgiveninthetextbookforChapter5_part2AsmallquizforChapter51、【单选题】Whenashafthavingacircularcrosssectionissubjectedtoatorque,thecrosssectionremainsplanewhileradiallinesrotate.Thiscausesa()withinthematerialthatvaries()alongany()line.本题答案：【shearstrain;linearly;radial】2、【单选题】Dueto()ofshear,thelinearshearstressdistributionwithintheplaneofthecrosssectionisalsodistributedalonganadjacent()oftheshaft本题答案：【complementaryproperty;axialplane】3、【单选题】Thetorsionformulaisbasedontherequirementthatthe()torqueonthecrosssectionisequaltothetorqueproducedbythe()shearstressdistributionaboutthe()oftheshaft.本题答案：【resultant;linear;longitudinalaxis】4、【单选题】Itisnecessarythattheshaftortubehavea()crosssectionanditismadeof()materialwhichhas()behavior.本题答案：【circular;homogeneous;linear-elastic】5、【单选题】Itisimportantforthedevelopmentoftheformulafortheangleoftwist,whichisthattheappliedtorquesdonotcause()ofthematerialandthatthematerialis()andbehavesina()manner本题答案：【yielding;homogeneous;linear-elastic】6、【单选题】Thesolidcircularshaftissubjectedtoaninternaltorqueof.TheshearstressdevelopedatpointsAandBare()and(),respectively.本题答案：【79.58MPa,59.68MPa】7、【单选题】TheshearstressdevelopedatpointAonthesurfaceoftheshaftis().Theshafthasaradiusof60mm.本题答案：【11.79MPa】8、【单选题】The40-mm-diameterA-36steelshaftissubjectedtothetorquesshown.TheangleoftwistofendAwithrespecttoCis().TheshearmodulusofA-36steelis75GPa.本题答案：【-0.0424】9、【单选题】Aseriesofgearsaremountedonthe60-mmdiameterA-36steelshaft.TheangleoftwistofgearBrelativetogearAis().TheshearmodulusofA-36steelis75GPa.本题答案：【0.0021】10、【单选题】Thehollow6061-T6aluminumshafthasanouterandinnerradiusofco60mmandci20mm,respectively.TheangleoftwistofendAis().TheflexiblesupportatBhasatorsionalstiffnessof.Theshearmodulusof6061-T6aluminumis26GPa本题答案：【0.0352】HomeworkassignmentforChapter6.1HomeworkassignmentforChapter6.2AsmallquizforChapter61、【单选题】Beamsare()straightmembersthatcarryloads()theirlongitudinalaxis.本题答案：【long,perpendicularto】2、【单选题】Inordertoproperlydesignabeam,itisimporttoknowthevariationof()and()alongitsaxisinordertofindthepointswherethesevaluesareamaximum.本题答案：【theshear,bendingmoment】3、【单选题】Althoughthechoiceofasignconventionforabeamis(),wewillusetheoneoftenusedinengineeringpractice.Thepositivedirectionsareasfollows:thedistributedloadacts()onthebeam;theinternalshearforcecausesa()rotationofthebeamsegmentonwhichitacts;andtheinternalmomentcauses()inthetopfibersofthesegments.本题答案：【arbitrary;downward;clockwise;compression】4、【单选题】Thecrosssectionofastraightbeamremainsplanewhenthebeamdeformsduetobending.Thiscauses()ononesideofthebeamand()ontheotherside.Theneutralaxisissubjectedto().本题答案：【tensilestress;compressivestress;zerostress】5、【单选题】Duetothepurebendingdeformation,thelongitudinal()strainvaries()from()attheneutralaxistoamaximumattheouterfibersofthebeam.本题答案：【normal;linearly;zero】6、【单选题】Providedthematerialis()and(),duetothepurebendingdeformation,thestressvariesina()fashiononthecrosssection.本题答案：【homogeneous;linearelastic;linear】7、【单选题】Forlinear-elasticmaterialtheneutralaxispassesthroughthe()ofthecross-sectionalarea.Thisconclusionisbasedonthefactthattheresultant()actingonthecrosssectionmustbe().本题答案：【centroid;axialnormalforce;zero】8、【单选题】Theflexureformulaisbasedontherequirementthatthe()onthecrosssectionisequaltothe()producedbythe()distributionabouttheneutralaxis.本题答案：【resultantmoment;moment;linearnormalstress】9、【单选题】Theflexureformulacanbeappliedonlywhenbendingoccursaboutaxesthatrepresenttheprincipalaxesofinertiaforthecrosssection.Theseaxeshavetheiroriginat()andareorientatedalong(),ifthereisone,andperpendiculartoit.本题答案：【thecentroid;anaxisofsymmetry】10、【单选题】Ifthemomentisappliedaboutsomearbitaryaxis,thenthemomentmustberesolvedintocomponentsalongeachof(),andthestressatapointisdeterminedby()ofthestresscausedbyeachofthemomentcomponents.本题答案：【theprincipalaxes,superposition】11、【单选题】IfthebeamissubjectedtoabendingmomentofM=16kN.m,themaximumbendingstressinthebeamis().本题答案：【59.6MPa】12、【单选题】IfthebeamissubjectedtoabendingmomentofM=15kN.m,themaximumbendingstressinthebeamis().本题答案：【5.88MPa】13、【单选题】IfthebeamissubjectedtoabendingmomentofM=10kN.m,thebendingstressdevelopedatpointAis().本题答案：【3.96MPa(Tension)】14、【单选题】ThebendingstressdevelopedatcornersAis().本题答案：【42MPa(Tension)】15、【单选题】Themaximumstressinthebeam'scrosssectionis().本题答案：【64.6psi】HomeworkassignmentforChapter7_part1HomeworkassignmentforChapter7_part2AsmallquizforChapter71、【单选题】Shearforcesinbeamscause()shear-straindistributionsoverthecross-section,causingitto().本题答案：【nonlinear,warp】2、【单选题】Duetothe()propertyofshearstress,theshearstressdevelopedinabeamactsonboththecrosssectionandon()planes.本题答案：【complementary,longitudinal】3、【单选题】Theshearformulawasderivedbyconsidering()equilibriumofthelongitudinalshearstressand()distributionactingonaportionofadifferentialsegmentofthebeam.本题答案：【horizontalforce,bending-stress】4、【单选题】Theshearformulaistobeusedonstrainghtprismaticmembersmadeof()materialthathas()behavior.Also,theinternalresultantshearforcemustbedirectedalonganaxisof()ofthecross-sectionalarea.本题答案：【homogeneous,linear-elastic,symmetry】5、【单选题】Forabeamhavingarectangularcrosssection,theshearstressvaries()with().Themaximumshearstressisalongthe()axis.本题答案：【parabolically,depth,neutral】6、【单选题】Shearflowisameasureoftheforceperunitlengthalonga()axisofabeam.Thisvalueisfoundfromthe()andisusedtodeterminetheshearforcedevelopedinfastenersandgluethatholdsthevarioussegmentsofabeamtogether.本题答案：【longitudinal,shearformula】7、【单选题】Ifamemberismadefromsegmentshavingthinwallsunderinternalshearforce,onlytheshearflow()tothewallsofthememberisimportant.Theshearflowvaries()alongsegmentsthatare()thedirectionoftheshearforceV.本题答案：【parallelto,linear,perpendicularto】8、【单选题】Theshearflowinthethin-walledmembervaries()alongthesegmentsthatare()or()thedirectionoftheshearforceV.Onthecrosssection,theshearflowsalongthesegmentssothatitcontributestotheshearforceVyetsatisfieshorizontalandvertical().本题答案：【parabolically,inclined,parallelto,forceequilibrium】9、【单选题】IfthebeamissubjectedtoashearforceofV=80kN,determinetheshearstressdevelopedatpointA.RepresentthestateofstressatAonavolumeelement.本题答案：【14.7MPa】10、【单选题】Determinetheabsolutemaximumshearstressdevelopedinthebeam.本题答案：【750psi】11、【单选题】IfthebeamissubjectedtoashearforceofV=10kN,determinethemaximumshearstressdevelopedinthebeam.本题答案：【0.6MPa】12、【单选题】Thetwoidenticalboardsareboltedtogethertoformthebeam.Determinethemaximumallowablespacingsoftheboltstothenearestmmifeachbolthasashearstrengthof30kN.ThebeamissubjectedtoashearforceofV=40KN.本题答案：【200mm】13、【单选题】Twoidentical20-mmthickplatesareboltedtothetopandbottomflangetoformthebuilt-upbeam.IfthebeamissubjectedtoashearforceofV=200KNdeterminetheallowablemaximumspacingsoftheboltstothenearestmm.Eachbolthasashearstrengthof20kN.本题答案：【96mm】HomeworkassignmentsforChapter8HomeworkassignmentsforChapter9AquizforChapter91、【单选题】Thegeneralstateofplanestressatapointisrepresentedbyacombinationoftwo()stresscomponentsandone()stresscomponent,whichacton()facesoftheelement.本题答案：【normal,shear,four】2、【单选题】Thestateofplanestressatthepointisuniquelyrepresentedby()stresscompomentsactiongonanelementthathas()atthepoint.本题答案：【three,aspecificorientation】3、【单选题】Theprincipalstressesrepresentthe()atthepoint.本题答案：【maximumandminimumnormalstress】4、【单选题】Whenthestateofstressisrepresentedbythe(),noshearstresswillactontheelement.Thestateofstresscanalsoberepresentedintermsofthemaximumin-planeshearstress.Inthiscase,()willalsoactontheelement.本题答案：【theprincipalstresses,anaveragenormalstress】5、【单选题】Themaximumrepresentingthemaximumin-planeshearstresswiththeassociated()isoriented()fromtheelementrepresentingtheprincipalstresses.本题答案：【averagenormalstresses,45degree】6、【单选题】Thegeneralthree-dimensionalstateofstressatapointcanberepresentedbyanelementorientedsothatonly()actonit.本题答案：【threeprincipalstresses】7、【单选题】Ifthein-planeprincipalstressesbothhavethesamesign,theabsolutemaximumshearstresswilloccur()andhasavalueof()本题答案：【out-of-plane,/2】8、【单选题】Ifthein-planeprincipalstressesareofoppositesigns,thentheabsolutemaximumshearstressequals(),thatis().本题答案：【themaximumin-planeshearstress,/2】9、【单选题】ThenormalstressandshearstressactingontheinclinedplaneABis()kPaand()kPa,respectively.本题答案：【150,259.81】10、【单选题】Theequivalentstateofstressonanelementatthesamepointthatrepresentsthemaximumin-planeshearstressatthepointincludesthenormalstressof()kPaandtheshearstressof()kPa.本题答案：【500,500】11、【单选题】Theequivalentstateofstressonanelementatthesamepointthatrepresentsthemaximumprincipalstressesatthepointincludesthenormalstressof()kPaandtheshearstressof()kPa.Thecorrespondingorientationoftheelementwithrespecttotheelementshownis().本题答案：【64.05,0,25.1(counterclockwise)】12、【单选题】Thebeamissubjectedtotheloadatitsend.ThemaximumprincipalstressatpointBis().本题答案：【335.56MPa】13、【单选题】Thehollowcircularshaftissubjectedtothetorqueof5kNm.Theprincipalstressdevelopedatapointonthesurfaceoftheshaftis().本题答案：【72.76MPa,-72.76MPa】HomeworkassignmentsforChapter12AquizforChapter121、【单选题】Inordertoderivethemoment-curvaturerelationship,theanalysiswillrequiretheuseofthreecoordinates.thexaxisextendspositivetotheright,alongthe()axisofthebeam.Itisusedtolocatethedifferentialelement,havinganundeformedwidthdx.Thevaxisextends()fromthexaxis.Itmeasuresthe()ofthecentroidonthecross-sectionalareaoftheelement.本题答案：【longitudinal,positiveupward,displacement】2、【单选题】Inordertodeterminetheslopeanddisplacementofabeambyintegration,itisimportanttousethepropersignsforM,Vorw.Positivedeflectionvis()andasaresult,thepositiveslopeanglewillbemeasured()fromtheispositivetothe().本题答案：【upward,counterclockwise,right】3、【单选题】Severalpossibleboundaryconditionsareoftenusedtosolveveandeflectionproblems.Forexample,ifthebeamissupportedbyarollerorpin,thenitisrequiredthatthe()bezeroatthesepoints.Ifthesesupportsarelocatedattheendsofthebeam,the()inthebeammustbezero.Atthefixedsupport,the()arebothzero.本题答案：【displacement,internalmoment,slopeanddisplacement】4、【单选题】Thedifferentialequationsatisfiesthetwonecessaryrequirementsforapplyingtheprincipleofsuperposition;i.e.,theloadis()relatedtothedeflection,andtheloadisassumednottochangesignificantly()ofthebeam.本题答案：【linearly,theoriginalgeometry】5、【单选题】Theadditional()onthebeamorshaftthatarenotneededtokeepitin()arecalledredundants.Thenumberoftheseredundantsisreferredtoasthe().本题答案：【supportreactions,stableequilibrium,degreeofindeterminacy】6、【单选题】Themethodofsuperpositionhasbeenusedtosolvefortheredundantloadingsontransverselyloadedbeams.Inordertoapplythismethodtothesolutionofstaticallyindeterminatebeams,itisfirstnecessarytoidentifythe().Byremovingthemfromthebeamweobtaintheso-called()beam,whichisstaticallydeterminateandstable,andissubjectedontothe().本题答案：【redundantsupportreactions