材料力学双语教学资料

材料 关于××同志的政审材料调查表环保先进个人材料国家普通话测试材料农民专业合作社注销四查四问剖析材料 力学双语教学学习资料1主讲教师：陈晓峰第一章绪论Chapter1Introduction§1-1材料力学的任务TheTasksofMechanicsofMaterials1＊.材料力学:MechanicsofMaterials2.构件:StructuralMembers3.变形:Deformation4＊.强度:Strength5＊.刚度:Rigidity6＊.稳定性:Stability§1-2变形固体的基本假设FundamentalAssumptionsofSolidDeformationBodies1.连续性假设:Continuity2.均匀性假设:Homogeneity3.各向同性假设:Isotropy§1.3外力及其分类ExternalForcesandClassification1.分布力:DistributedForce2.集中力:PointForce3.静载荷:StaticLoad4.动载荷:DynamicLoad§1.4内力、截面法和应力的概念ConceptsofInternalForces，MethodofSectionandStress1＊.内力:InternalForce2＊.截面法:MethodofSection3.截面法的三个步骤：截开，代替，平衡Threestepsofmethodofsection:cutoff,substitute,andequilibrium.4＊.应力:Stress5.平均应力：Averagestress6.应力（全应力）：Wholestress（sumstress）7＊.正应力:NormalStress8＊.剪应力(切应力)：ShearingStress§1.5变形与应变DeformationandStrain线应变:Strain剪应变:ShearingStrain§1.6杆件变形的基本形式BasicTypesofDeformationsofRods1＊.拉伸或压缩:TensionorCompression2＊.剪切:Shear3＊.扭转:Torsion4＊.弯曲:Bending第二章拉伸、压缩与剪切Chapter2Tension，CompressionandShear§2.1轴向拉伸与压缩的概念和实例TheConceptandExamplesofAxialTensionandCompression1.拉杆:TensileRod2.压杆:CompressiveRod3.受力特点：外力合力的作用线与杆轴线重合CharacteristicoftheExternalForces:Theactinglineoftheresultantofexternalforcesiscoincidedwiththeaxisoftherod.4.变形特点：杆沿轴向伸长或缩短CharacteristicofDeformation:Rodwillelongateorcontractalongtheaxisoftherod.§2.2轴向拉伸或压缩时横截面上的内力和应力InternalForceandStressofAxialTensionorCompressionontheCrossSection1＊.横截面:CrossSection2＊.轴力:NormalForce3＊.轴力图:DiagramofNormalForce§2.3直杆轴向拉伸或压缩时斜截面上的应力StressofAxialTensionorCompressionontheSkewSection1.斜截面:SkewSection2.§2.4材料在拉伸时的力学性能MechanicalPropertiesofMaterialswithTensileLoad1.标准试件:Specimen2.低碳钢(C≤0.3%):LowCarbonSteel3.弹性阶段:ElasticRegion4.屈服阶段:YieldingStage5.强化阶段:HardeningStage6.颈缩阶段:NeckingStage7＊.σp----比例极限:ProportionalLimit8＊.σe----弹性极限:ElasticLimit9＊.σs----屈服极限:YieldingStress10＊.σb----强度极限:UltimateStress11.延伸率:PercentElongation12.断面收缩率:PercentReductionofArea13.塑性材料:DuctileMaterials14.脆性材料:BrittleMaterials15.铸铁:Castiron§2.7失效、安全系数和强度计算Failure,SafetyfactorandStrengthcalculation1＊.许用应力:AllowableStress2.安全系数:SafetyFactor3＊.强度条件:StrengthCondition4＊.强度校核:Checkstrength5＊.截面设计:Sectiondesign6＊.确定许可载荷:Determineallowableload§2.8轴向拉伸或压缩时的变形DeformationinAxialTensionorCompression1.弹性变形:ElasticDeformation2.塑性变形:PlasticDeformation3.纵向应变:LongitudinalStrain4.横向应变:LateralStrain5．线弹性变形:LinearElasticDeformation6.泊松比:Poisson’sratio7＊.弹性模量-E：表示材料抵抗拉压变形的能力E-modulusofelasticity：Indicatesthecapabilityofmaterialsforresistingtensionorcompression8＊.抗拉刚度-EA:表示构件抵抗拉压变形的能力EA-theaxialrigidity:Indicatesthecapabilityofconstructivemembersforresistingtensionorcompression9＊.胡克定律（Hooke’sLaw）:当应力不超过材料的比例极限时，应力与应变成正比.Thestressisproportionaltothestrainwithintheelasticregion.§2.12应力集中的概念TheConceptofStressConcentration1.由于截面尺寸的突然变化，使截面上的应力分布不再均匀，在某些部位出现远大于平均值的应力，称应力集中。Discontinuitiesofcrosssectionmayresultinhighlocalizedorconcentratedstresses.2.理论应力集中系数K：TheoreticalStress-concentrationFactor-K§2.13剪切和挤压的实用计算PracticalCalculationofShearandBearing1＊.剪切：Shear2.剪切面：ShearingPlane3＊.剪切面上的内力-剪力：InternalForceinShearingPlane-ShearingForce4.剪切的实用计算：PracticalCalculationofShear5.挤压的实用计算：PracticalCalculationofBearing6.挤压强度条件：工作中的挤压应力不应超过许用挤压应力。Strengthconditionofbearing：Workingbearingstressshouldnotexceedtheallowablebearingstress.第三章扭转ChapterThreeTorsion§3.1扭转的概念和实例ConceptandExamplesofTorsion1.电动机:Generator2.涡轮:Turbine3＊.扭转的受力特点：杆件的两端作用着大小相等，方向相反，且作用面垂直于杆件轴线的力偶。Characteristicofloads:Shaftisloadedbyatorsionalcoupleinplanesthatareperpendiculartotheaxisoftheshaft.4＊.变形特点：杆件的任意两个横截面发生绕轴线的相对转动。Characteristicofdeformation:anytwocrosssectionswilltwistalongtheaxis.5＊.轴:Shaft§3.2外力偶矩的计算扭矩和扭矩图CalculationoftheexternaltorqueInternaltorqueandItsdiagram1．扭转外力偶矩的计算：Calculationoftheexternaltorque2＊.扭矩：InternalTorque3.符号规定：Signconvention4＊.右手螺旋法则:Righthandscrewrule5＊.扭矩图：DiagramofInternalTorque§3.3纯剪切PureShear1.薄壁圆筒的扭转实验：Experimentofthin-walledcirculartubeundertorsion2.变形特点:Charactersofdeformations：截面间的距离不变;所有横截面的位置不变;所有纵向线转过了一个角度γ。Distancesbetweenthesectionsremainunchanged,Allcrosssectionsremainunchanged,Allthegeneratinglinesrevolvethroughanangleγ.3＊.切应力互等定理：Theoremofcomplementaryshearingstresses4＊.切应变：Shearingstrain5＊．剪切虎克定律：Hooke’slawofshear6＊.剪切弹性模量G：Modulusofelasticityofshearing第四节圆轴扭转时的应力Stressesinaroundshaftundertorsion)1＊.Ip(极惯性矩)---polarmomentofinertia2＊.Wp(抗扭截面系数)----sectionmodulusintorsion§3.5圆轴扭转时的变形1.扭转角:Theangleoftwist2＊.抗扭刚度GIp：thetorsionalrigidity3＊.扭转的刚度条件:Rigidityconditionintorsion4.单位长度扭转角：TheangleoftwistperunitlengthExercises1.Abracket（支架）isshowninthefigure，Thecross-sectionareaofthesteelbarABisA1=6cm2；thecross-sectionareaofthewoodenbarBCisA2=300cm2，Knowingtheallowablestressofsteelis[σ]=140MPa,theallowabletensilestressofwoodis[σ]L=8MPa,andtheallowablecompressivestressofwoodis[σ]Y=4MPa.TrydeterminetheallowableloadPofthebracket.2.Awoodentenon(榫)jointisshowninthefigure.Knowingthatthequantitiesarea=b=12cm，h=35cm，c=4.5cmandP=40KN.Trytodeterminetheshearingstressandbearingstressforthejoint.3．Twoboardsareboltedtogetherasshown.Eachboardhasathickness(δ)of2mm,andawidth(b)of15mm.Thediameterdoftheboltis4mm.Allthepartsaremadefromthesamematerialandhavethesameallowablestresses160MPa,=100MPa,300MPa.TrytodesignthetensileforceF.4.Atensilebarandtwocoverboardsareboltedtogetherasshown.Eachcoverboardhasathicknessof8mm.Allthepartsaremadefromthesamematerialandhavethesameallowablestresses80MPa,=60MPa,160MPa.Thethicknessofthebar=15mm,thetensileforceF=120KN.Trytodesignthediameterdofthebolt.thewidthbofthetensilebar.5．构件在外力作用下抵抗破坏的能力称为；构件在外力作用下抵抗变形的能力称为；构件在外力作用下保持原有平衡状态的能力称为。(PleasefillintheblankswithproperwordsinEnglish.)6．杆件的基本变形一般有　、　、　、　、四种。(PleasefillintheblankswithproperwordsinEnglish.)第四章弯曲内力ChapterFourInternalForcesinBending§4-1弯曲的概念和实例§4-1TheConceptsandExamplesinBending1＊．梁：beam2．轴线：axis3．纵向对称面：longitudinalplaneofsymmetry4＊．平面弯曲：planebending5＊．弯曲的受力特点：作用于杆件上的外力或外力偶矩矢垂直于杆件轴线。Characteristicsofloads:externalforcesorexternalthecouplevectorperpendiculartotheaxisoftherod.6＊．弯曲的变形特点：杆件的轴线由直线变为曲线。Characteristicsofdeformations:theaxisoftherodchangeintocurvefromoriginalstraightlines.7＊．弯曲变形：杆件在垂直于杆轴线的外力或两个外力偶的作用下，杆的轴线由直线变为曲线，这种变形称为弯曲变形。BENDING:Theactionoftheexternalforceorexternalthecouplevectorperpendiculartotheaxisoftherodmakestheaxisoftherodchangeintocurvefromoriginalstraightlines,thisdeformationiscalledbending.§4-2受弯杆件的简化§4-2SimplificationofBendingRods集中力：concentratedforce分布力：distributedload均布载荷：uniformload支座：support5＊.简支粱：simplesupportedbeam6＊.外伸梁：overhangingbeam7＊.悬臂梁：cantileverbeam§4-3剪力和弯矩§4-3ShearingForceandBendingMoment1.弯曲内力：internalforcesinbending2＊.剪力：shearingforce3＊.弯矩：bendingmoment4.内力的正负规定：signconventionsfortheinternalforces§4-4剪力方程和弯矩弯矩方程剪力图和弯矩图§4-4TheEquationsofShearingForceandBendingMomentTheDiagramsofShearingForceandBendingMoment1＊．剪力方程：equationofshearingforce2＊．弯矩方程：equationofbendingmoment3＊．剪力图：diagramofshearingforce4＊．弯矩图：diagramofbendingmoment§4-5载荷集度、剪力和弯矩间的关系§4-5RelationsamongtheIntensityofDistributedLoad,ShearingForceandBendingMoment1＊.微分关系：differentialrelations2＊.规律法：methodofregulation3＊.控制截面法：methodofcontrolsections水平直线：horizontalstraightline斜直线：inclinedstraightline突变：suddenchange增函数：increasingfunction减函数：decreasingfunction盆状抛物线：basin-likecurve坟状抛物线：tomb-likecurve折向与P相反：flexibleoppositetoP第五章弯曲应力ChapterFiveStressesinBending§5-1纯弯曲§5-1PureBending1.横力弯曲：transversebending2＊.纯弯曲：purebending平面假设：横截面变形后仍为平面，只是绕中性轴发生转动，距中性轴等高处，变形相等。Hypothesisofplanesection:Thecrosssectionsremainstillplanes,andonlyrotatethroughsomeanglesaroundtheirneutralaxesafterdeformation.4＊.中性层：neutrallayer5＊.中性轴：neutralaxis纵向对称轴：longitudinalaxisofsymmetry§5-2纯弯曲时的正应力§5-2NormalStressinPureBending几何关系：geometricrelation物理关系：physicsrelation静力关系：staticrelation4＊.抗弯刚度EIz：flexuralrigidity§5-3横力弯曲时的正应力§5-3NormalStressinTransverseBending1＊.抗弯截面系数W：sectionfactorofbending2＊.弯曲的强度条件：strengthconditioninbending§5-4弯曲切应力§5-4ShearingStressinBending矩形截面梁：thebeamwithrectangularsection工字形截面梁：wide-flangebeam翼缘：flange腹板：web静矩：staticmoment6＊.惯性矩：momentofinertia焊接：melt铆接：rivet§5-6提高弯曲强度的措施§5-6MeasuresofIncreasingStrengthinBending合理安排梁的受力情况：arrangetheloadsofbeamreasonably跨度：span梁的合理截面：reasonablesectionofbeams4＊.等强度梁：equalstrengthbeams第六章弯曲变形ChapterSixDeformationsinBending§6-1工程中的弯曲变形问题§6-1TheProblemsofDeformationDuetoBendinginEngineering车床主轴：principalaxisoflathe振动：vibrate噪声：noise§6-2挠曲线的微分方程§6-2Thedifferentialequationofdeflectioncurve1.挠曲线：deflectioncurve2＊.挠度：deflection3＊.转角：angleofrotationorslope4.切线：tangent5.逆时针：counter-clockwise6.顺时针：clockwise7.曲率：curvature8.曲率半径：radiusofcurvature§6-3积分法求弯曲变形§6-3DeterminetheDeformationsinBendingbyIntegration1＊.微分方程：differentialequation边界条件：boundarycondition连续性条件：continuitycondition积分常数：integralconstants5＊.转角方程：equationofangleofrotation6＊.挠曲线方程：equationofdeflectioncurve刚度条件：rigiditycondition镗床：boringmachine镗刀：boringtool§6-4叠加法求弯曲变形§6-4DeterminetheDeformationsinBendingbytheMethodofSuperposition1＊.叠加法：themethodofsuperposition桥式起重机：overheadtravelingcrane§6-5简单超静定梁§6-5IndeterminateSimpleBeams静定梁：staticallydeterminatebeam超静定梁：staticallyindeterminatebeam变形协调方程：equationofcompatibilityofdeformations§6-6提高弯曲刚度的一些措施§6-6MeasuresofIncreasingRigidityinBending增大抗弯刚度：increaseflexuralrigidity减少跨度或增加支承：decreasespanorincreasesupports减小弯矩：decreasebendingmoment选择合理的截面形状：selectthereasonablesectionsExercises1.AcantileverbeamAB.Thedistributedloadof3kN/mextendsover0.8mofthebeamandthe1kNloadisappliedatpointE.Plotthediagramsofsharingforceandbendingmoment.2.Theallowablestressofthewoodenbeamshowninthefigureis[σ]=10MPa.Trytodeterminethemaximumdiameterdofthecircularholeincasethatthestrengthofthebeamissatisfied(neglectingstressconcentrations).3．DeterminetheangleofrotationofpointAandthedeflectionofpointCbythemethodofsuperposition.