中国石油大学工程力学考试Exam11121AWord格式.docx
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中国石油大学工程力学考试Exam11121AWord格式.docx
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(1)σd1<
σd2;
(2)σd1=σd2;
(3)σd1>
(4)Cannotbejudged.
6.(4points)WeightofthebodyisW,andpushingforceisP.W=160N,P=500N.ThestaticandkineticslidingfrictioncoefficientsbetweentheweightandthewallareμS=0.3andμk=0.25respectively.Thenthefrictionbetweentheweightandthewallis
a.150N;
b.125N;
c.100N;
d.500N.
7.(4points)Thebarsinthestructuresasfollowingaremadeofsamematerialandwithsamediameter.|NBC1|_____(>
=,<
)|NBC2|,PCr1______(>
)PCr2.
II(10points)Usingthemethodofcompositeareas,calculatecentroidalprincipalmomentsofinertia
and
fortheshadedregionasshowninFig.II.
Fig.II.
III(13points)ForabeamshowninFig.III,drawitsbendingmomentandshearforcediagrams.
Fig.III.
IV(20points)AhorizontalbracketABCisfixedatsupportAandfreeatC.Thebracketisconstructedfromacircularcross-sectionalbarwithconstantdiameterd.AverticalloadPactsatthefreeendC.
(1)Determinetheplacesofthecriticalpoints.
(2)Drawstresselementstoshowthestressstateofthecriticalpoints.(3)Ifd=30mm,a=1m,P=180Nandtheallowablestressis[σ]=80MPa,examthestrengthofthebracketaccordingtothe4thstrengthcondition.
V(12points)Fortheprismaticbar,takingitsweightinconsideration,findthedisplacementofsectionB.LoadingF,l,crosssectionareaA,elasticmodulusEandmassdensityρareknown.
VI.(15points)Forthestaticindeterminatebeam,findthereactionatBwithenergymethod.
isknown。
B卷
中国石油大学(北京)2011—2012学年第一学期
《工程力学(双语)》期末考试试卷
考试方式(闭卷考试)
班级:
姓名:
学号:
题号
I
II
III
IV
V
VI
总分
得分
(试卷不得拆开,所有答案均写在题后相应位置)
I(Total30points)Filluptheblankswithcorrectanswer.
1.(4points)Theboundaryconditionsonleftendforabeamasshownare.
2.(6points)Asshown,astraingageispastedonthesurfaceofacircularbarwithdiameterdtotestthetorquesactingontwoends.Ifelasticmodulus
andpoission’sratio
ofthematerialareknownandthestrainingageis
thetorque
=.
(a)
(b)
(c)
(d)
3.
(4points)Stress-straincurvesforthreematerialsareshownbelow.Material(1,2,3)hasthehighestultimatestress.Material(1,2,3)hasthelargestelasticmodulus.
5.(4points)WeightofthebodyisW,andpushingforceisP.W=160N,P=500N.ThestaticandkineticslidingfrictioncoefficientsbetweentheweightandthewallareμS=0.3andμk=0.25respectively.Thenthefrictionbetweentheweightandthewallis
6.
(4points)Thebarsinthestructuresasfollowingaremadeofsamematerialandwithsamediameter.|NBC1|_____(>
7.(4points)Fortwobeamsmadeofsamematerial,thecorrectrelationshipfortheirmaximumdynamicstressesis.
II(13points)ForabeamshowninFig.II,drawitsbendingmomentandshearforcediagrams.
Fig.II.
III(10points)Usingthemethodofcompositeareas,calculatecentroidalprincipalmomentsofinertia
fortheshadedregionasshowninFig.III.
Fig.III.
IV(15points)Forthestaticindeterminatebeam,findthereactionatBwithenergymethod.
V.(20points)AhorizontalbracketABCisfixedatsupportAandfreeatC.Thebracketisconstructedfromacircularcross-sectionalbarwithconstantdiameterd.AverticalloadPactsatthefreeendC.
(1)Determinetheplacesofthecriticalpoints.
(2)Drawstresselementstoshowthestressstateofthecriticalpoints.(3)Ifd=30mm,a=1m,P=180Nandtheallowablestressis[σ]=80MPa,examthestrengthofthebracketaccordingtothe3thstrengthcondition.
VI.(12points)Fortheprismaticbar,takingitsweightinconsideration,findthedisplacementofsectionB.LoadingF,l,crosssectionareaA,elasticmodulusEandmassdensityρareknown.
C卷
I(Total40points)Filluptheblankswithcorrectanswer.
1.(5Points)Fig.I.1isatypicallow-carbonsteelσ-εdiagramintension.Suchadiagramconveysimportantinformationaboutthemechanicalbehaviorforthematerial.Pointarepresents______,pointbrepresents______,pointcrepresents______,pointdrepresents______,pointerepresents______.
(1)yieldstress
(2)ultimatestress(3)elasticlimit
(4)percentelongation(5)proportionallimitFig.I.1
2.(5points)ApieceofchalkshowninFig.I.2issubjectedtoacombinationoftwistingandtension,failsontheα-degreeplanewiththelongitudinalaxis.ThesensesofthetorquesandaxialforcesmustbeindicatedasshowninFig..
Fig.I.2
3.(5Points)Forarealmemberundergoingrepeatedstress,itscharacterofcycler=.Whenr=,itsendurancelimitisthesmallest.
a.
b.
c.+1d.–1e.0f.–∞g.0.5
4.(5points)Theboundaryconditionsonleftendforabeamasshownare.
5.(5points)Whenatrainpassthroughasteelbridge,thestrainstestedbyinstrumentareεx=0.0004,εy=-0.00012atpointA.ThenormalstressesindirectionsxandyatpointAareσx=,σy=.(E=200GPa,μ=0.3,σz=0)
6.(5points)Fortwobeamsmadeofsamematerial,thecorrectrelationshipfortheirmaximumdynamicstressesis.
7.(5points)WeightofthebodyisW,andpushingforceisP.W=160N,P=500N.ThestaticandkineticslidingfrictioncoefficientsbetweentheweightandthewallareμS=0.3andμk=0.25respectively.Thenthefrictionbetweentheweightandthewallis
8.(5points)Thebarsinthestructuresasfollowingaremadeofsamematerialandwithsamediameter.|NBC1|_____(>
II(15points)ForabeamshowninFig.II,drawitsbendingmomentandshearforcediagrams.
III(15points)Infigurethereisamanualwinch.Thediameterofthesteelshaftisd=30mmandtheallowablestressis[σ]=80MPa.Findthemaximumloadforthewinch,accordingtothe4thstrengthcondition.
IV(15points) ArigidbarABoflengthLishingedtoawallatAandsupportedbytwoverticalbarslabeled1and2attachedatpointsCandD.Thebars1and2havethesamecross-sectionalareaAandaremadeofthesamematerial(modulusE),butthebar2istwiceaslongasthebar1.(a)FindthetensileforcesN1andN2inthebarsduetotheverticalloadPactingatendBofthebar.(b)FindthedownwarddisplacementδBatendBofthebar.
V.(15points)FindthereactionatthesupportBforthebeamwithloadsasfollowing.(EnergyMethodrecommended)
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