材料力学总结.docx
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材料力学总结.docx
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材料力学总结
材料力学总结
材料力学总结
材料力学名词解释及填空
名词解释
1、Stress(应力)
theforceperunitarea,orintensityoftheforcedistributedoveragivensection,iscalledstress.
σ=F/A
2、normalstress(正应力)
Theinternalforceisthereforenormaltotheplaneofthesectionandthecorrespondingstressisdescribedasthenormalstress.
3、Shearingstress(剪应力)
Theinternalforceistheshearontheplaneofthesectionandthecorrespondingstressisdescribedastheshearingstress.
4、LinearStrain(应变)
Thenormalstrainεinamembercanbedefinedasthedeformationofthemeteroftheperunitlength.
5、Themainobjectiveofthestudythemechanicsofmaterials(材料力学的任务)istoprovidethefutureengineerwiththemeansofanalyzinganddesigningvariousmachinesandloading-bearingstructures.
6、Saint-venant’sprinciple(圣维南原理)
Fortwosetsofstaticallyequivalentforces,exceptintheimmediatevicinityofthepointsofapplicationoftheloads,thestressdistributionmaybeassumedindependentoftheactualmodeofapplicationoftheloads(thisstatementisnotonlytoaxialload,buttopracticallyanytypeofload)
7、Work-energyprinciple(功能原理)
TheWork-energyPrinciple:
Intheprocessofthedeformationofaelastomer,thestrainenergywhichisstoredinelastomerisequaltotheworkoftheexternalforceinnumber.ThisistheWork-energyPrincipleanditcanberepresentedasVε=W.
8、effectivelength(有效长度)isdefinedasreallengthmultipliedbyfactoroflength
9、principleplane(主平面)
istheplaneinwhichtheshearingstressequalszero,andnormalstressesachievemaximumorminimum.
Principlestress(主应力)
Thenormalstresswhichisexertedontheprincipleplaneiscalledtheprinciplestress.
10、Radiusofradiusofgyration【revolution】(惯性半径)ofanareacanbecalculatedbythefollowingformulai=I/A
Wherei=themomentofinertiaofanarea
A=theareaofancrosssection
11、isotropicmaterials(各向同性材料)arethematerialswhoseelasticconstantsareindependentofdirection.
12、homogeneousmaterials(均匀性材料)arethematerialswhoseelasticpropertiesarethesameeverywhere.
13、Thestrainenergydensity(应变能密度)
Thestrainenergyintheunitvolumecanbedefinedasthestrainenergydensity.
14、Hooke’slaw(胡克定律)maybeexpressedmorefullybysayingthat
1】whenthestressincreases,themeasuredstrainincreasesinthesameratio
2】whenthestressdiminishes,themeasuredstraindiminishesinthesameratio
3】whenthestressisremoved,nostraincanbemeasured
Forasmalldeformation,thestressisdirectlyproportionaltothestrain.
15、Hooke’slawforshearingstress(剪切胡克定律)
Therelationτ=GγisknownasHooke’slawforshearingstress.StrainandconstantGiscalledthemodulusofrigidityorshearmodulusofmaterial.
16、GeneralizedHooke’slaw(广义胡可定律)
17、Poissonratio(泊松比)isdefinedastheratiooflateralcontraction(strain)tolongitudinalextension(strain)ofabarunderterminaltension.
18、factorofsafety(安全因数)ultimateloadoverallowableload
19、stress-concentrationfactork(应力集中因数K)=maximumstressoveraveragestress
20、staticallyindeterminateproblem(静不定问题)istheprobleminwhichthereactionsandinternalforcescannotbedeterminedbystaticonly,analysisofdeformationisneeded.
21、neutralsurface(中性层)isdefinedasthesurfacebetweenthetopandbottomofabeaminwhichlongitudinallinedonotchange.
22、Neutralaxis(中性轴)
①Theneutralsurfaceintersectsatransversesectionalongastraightlinecalledtheneutralaxisofthesection.
②Theintersectionoftheneutralsurfacewithatransversesectioniscalledtheneutralaxisofthesection.
23、principleofsuperposition(叠加原理)
foralllinearsystems (a beam canbemodeledasalinearsystem),
24、thequantitythetermλ=μl/i(柔度)isknownastheslendernessratioofthecolumn.
Whereμl=effectivelength
i=theradiusofgyration
25、Thetheoryofstrength(强度理论)
Theassumptionconcerningthedamageorthelosingeffectofthematerialiscalledthetheoryofstrength.
26、buckling(失稳)
Astagewhenthecolumnsuddenlybecomessharplycurvedinsteadofremainingstraightastheloadisappliediscalledbuckling.
27、Thecriticalforce(临界压力)
Thevalueofthecompressiveforcewhichisrightontheboundarybetweenthestablebalanceandtheunstablebalanceiscalledthecriticalforce.
28、Thecriticalstress(临界应力)
Thecorrespondingstressofthecriticalforceisdescribedasthecriticalforce.
29、Euler’sFormula(欧拉公式)
Euler’sFormulacanbeexpressedas
Fcr=π²EI/le²
inwhich:
Fcrdenotesthecriticalload
Edenotesthemodulus
Idenotestheminimummomentofinertiaofarea
ledenotestheequivalentlength
30、Assumptionforabar(拉压的平面假设)
Thehypothesisassumesthatthesectionkeepsbeingaplaneafterdeformation.
31、Assumptionfortorsion(扭转平面假设)
Whenacircularshaftissubjectedtoatorsion,everycrosssectionremainsplaneandundamaged.
32、Assumptionforbending(弯曲平面假设)
Underbending,thecrosssectionofthebeamremainsplaneandhasaconstantcurvature.Andthenewcrosssectionstillperpendiculartoaxis.
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