材料力学总结

《材料力学总结》摘要：Theinternalforceisthereforenormaltotheplaneofthesectionandthecorrespondingstressisdescribedasthenormalstres,.剪应力）Theinternalforceistheshearontheplaneofthesectionandthecorrespondingstressisdescribedastheshearingstre，ss（.临界压力）Thevalueofthecompressiveforcewhichisrightontheboundarybetweenthestablebalanceandtheunstablebalanceiscalledthecriticalforce.材料力学名词解释及填空名词解释1、Stress（应力）theforceperunitarea,orintensityoftheforcedistributedoveragivensection,iscalledstress.=F/A、normalstress（正应力）Theinternalforceisthereforenormaltotheplaneofthesectionandthecorrespondingstressisdescribedasthenormalstress.、Shearingstress（剪应力）Theinternalforceistheshearontheplaneofthesectionandthecorrespondingstressisdescribedastheshearingstress.、LinearStrain（应变）Thenormalstrainεinamembercanbedefinedasthedeformationofthemeteroftheperunitlength.、Themainobjectiveofthestudythemechanicsofmaterials（材料力学的任务）istoprovidethefutureengineerwiththemeansofanalyzinganddesigningvariousmachinesandloading-bearingstructures.、Saint-venantsprinciple（圣维南原理）Fortwosetsofstaticallyequivalentforces,exceptintheimmediatevicinityofthepointsofapplicationoftheloads,thestressdistributionmaybeassumedindependentoftheactualmodeofapplicationoftheloads（thisstatementisnotonlytoaxialload,buttopracticallyanytypeofload）、Work-energyprinciple（功能原理）TheWork-energyPrinciple:Intheprocessofthedeformationofaelastomer,thestrainenergywhichisstoredinelastomerisequaltotheworkoftheexternalforceinnumber.ThisistheWork-energyPrincipleanditcanberepresentedasVε=W.8、effectivelength（有效长度）isdefinedasreallengthmultipliedbyfactoroflength、principleplane（主平面）istheplaneinwhichtheshearingstressequalszero,andnormalstressesachievemaximumorminimum.Principlestress（主应力）Thenormalstresswhichisexertedontheprincipleplaneiscalledtheprinciplestress.、Radiusofradiusofgyration【revolution】】（惯性半径）ofanareacanbecalculatedbythefollowingformulai=I/AWherei=themomentofinertiaofanareaA=theareaofancrosssection、isotropicmaterials（各向同性材料）arethematerialswhoseelasticconstantsareindependentofdirection.12、homogeneousmaterials（均匀性材料）arethematerialswhoseelasticpropertiesarethesameeverywhere.、Thestrainenergydensity（应变能密度）Thestrainenergyintheunitvolumecanbedefinedasthestrainenergydensity.、Hookeslaw（胡克定律）maybeexpressedmorefullybysayingthat1】whenthestressincreases,themeasuredstrainincreasesinthesameratio2】whenthestressdiminishes,themeasuredstraindiminishesinthesameratio3】whenthestressisremoved,nostraincanbemeasuredForasmalldeformation,thestressisdirectlyproportionaltothestrain.、Hookeslawforshearingstress（剪切胡克定律）Therelation=GisknownasHookeslawforshearingstress.StrainandconstantGiscalledthemodulusofrigidityorshearmodulusofmaterial.、GeneralizedHookeslaw（广义胡可定律）17、Poissonratio（泊松比海definedastheratiooflateralcontraction（strain）tolongitudinalextension（strain）ofabarunderterminaltension.、factorofsafety（安全因数）ultimateloadoverallowableload、stress-concentrationfactork（应力集中因数K）=maximumstressoveraveragestress、staticallyindeterminateproblem（静不定问题）istheprobleminwhichthereactionsandinternalforcescannotbedeterminedbystaticonly,analysisofdeformationisneeded.21、neutralsurface（中性层）isdefinedasthesurfacebetweenthetopandbottomofabeaminwhichlongitudinallinedonotchange.22、Neutralaxis（中性轴）①Theneutralsurfaceintersectsatransversesectionalongastraightlinecalledtheneutralaxisofthesection.②Theintersectionoftheneutralsurfacewithatransversesectioniscalledtheneutralaxisofthesection.、principleofsuperposition（叠加原理）foralllinearsystems（abeamcanbemodeledasalinearsystem）,、thequantitytheterm=l/i（柔度）isknownastheslendernessratioofthecolumn.Wherel=effectivelengthi=theradiusofgyration25、Thetheoryofstrength（强度理论）Theassumptionconcerningthedamageorthelosingeffectofthematerialiscalledthetheoryofstrength.、buckling（失稳）Astagewhenthecolumnsuddenlybecomessharplycurvedinsteadofremainingstraightastheloadisappliediscalledbuckling.、Thecriticalforce（临界压力）Thevalueofthecompressiveforcewhichisrightontheboundarybetweenthestablebalanceandtheunstablebalanceiscalledthecriticalforce.、Thecriticalstress（临界应力）Thecorrespondingstressofthecriticalforceisdescribedasthecriticalforce.、EulersFormula（欧拉公式）EulersFormulacanbeexpressedasFcr=EI／leinwhich:FcrdenotesthecriticalloadEdenotesthemodulusIdenotestheminimummomentofinertiaofarealedenotestheequivalentlength、Assumptionforabar（拉压的平面假设）Thehypothesisassumesthatthesectionkeepsbeingaplaneafterdeformation.、Assumptionfortorsion（扭转平面假设）Whenacircularshaftissubjectedtoatorsion,everycrosssectionremainsplaneandundamaged.、Assumptionforbending（弯曲平面假设）Underbending,thecrosssectionofthebeamremainsplaneandhasaconstantcurvature.Andthenewcrosssectionstillperpendiculartoaxis.、极惯性矩ThepolarmomentofinertiaofanareaisdefinedasthepolarmomentofinertiaofanareawithrespecttoapointastheintegralIp=dA、惯性矩ThemomentofinertiaofanareaisdefinedasthesecondmomentoftheareawithrespecttoanaxisastheintegralI=ydA.、静矩矩ThestaticmomentofanareaisdefinedasthefirstmomentofanareawithrespecttoanaxisastheintegralSz=ydA.填空题1三个材料假设Homogeneousityassumption、Continuityassumption、Isotropyassumption三个关系Geometricrelation、Physicalrelation、Equilibriumrelation限制梁挠度的三个条件Boundarycondition、Constraintcondition