Fatigue Life Design of Mechanical Structure智慧樹知到課后章節(jié)答案2023年下北京理工大學(xué)

FatigueLifeDesignofMechanicalStructure智慧樹知到課后章節(jié)答案2023年下北京理工大學(xué)北京理工大學(xué)

緒論單元測試

Excessdeformationis（）

A:StresscorrosioncrackingB:LittleplasticityC:HighenergyabsorptionD:Themostcommonfailuremode

答案:Themostcommonfailuremode

Thecorrectstatementoffatigueincludes（）

A:ConstantorvariableamplitudeB:Loading,uni/multi-axialloadingC:RepeatedloadingD:Cracknucleation/growth

答案:Constantorvariableamplitude;Loading,uni/multi-axialloading;Repeatedloading;Cracknucleation/growth

ThecontributionofAugustW?hlerisasfollows（）

A:FatiguelimitB:S-NCurveC:MultiplefatigueD:Corrosionfatigue

答案:Fatiguelimit;S-NCurve

Failureduetofatigue,i.e.repeatedloading,isthemostcommoncauseofmechanicalfailure.（）

A:錯B:對

答案:對

Properfatiguedesignincludessynthesis,analysisandtesting.（）

A:對B:錯

答案:對

第一章測試

Thecharacteristicsoffail-safedesignis（）

A:TheoldestcriterionB:ExpectedmaximumloadorstressoccuroccasionallyC:FracturemechanicsanalysisandtestsD:Ifonepartfails,thesystemdoesnotfail

答案:Ifonepartfails,thesystemdoesnotfail

Fourkindsofpossibledesignsituationsareasfollows（）

A:ModeldesignB:EquipmentdesignC:DesigntostandardD:Productdesign

答案:Modeldesign;Equipmentdesign;Designtostandard;Productdesign

Themainpointsofdamagetolerancedesignareasfollows（）

A:SlowcrackpropagationB:Anti-crackmeasuresC:MinimumdetectablecracksizeD:Highfracturetoughness

答案:Slowcrackpropagation;Anti-crackmeasures;Minimumdetectablecracksize;Highfracturetoughness

Analysisneedstobeconfirmedbytests.（）

A:錯B:對

答案:對

Allowableservicelifeshouldbelessthantestorcalculatedlife.（）

A:錯B:對

答案:對

第二章測試

Whichisnotthecharacteristicofslip（）

A:ThesamecharacteristicsundermonotonicloadingandcyclicloadingB:AsheardeformationofthemetalC:TherelationshipbetweendislocationsandplasticdeformationD:Occurringwithinindividualgrainsbydislocationmovement

答案:Thesamecharacteristicsundermonotonicloadingandcyclicloading

Thecharacteristicsofbeachmarkareasfollows（）

A:WavybandsB:PatternofcrackgrowthC:Crack’sstarting,stoppingandgrowingatdifferentratesD:Twoadjacentcracksurfaceswithopen,close,andrub

答案:Wavybands;Patternofcrackgrowth;Crack’sstarting,stoppingandgrowingatdifferentrates;Twoadjacentcracksurfaceswithopen,close,andrub

Modesoffatiguecrackgrowthwithfractureareasfollows（）

A:SlipdeformationB:Inter-crystallinefractureC:Trans-crystallinefractureD:Dislocationmovement

答案:Inter-crystallinefracture;Trans-crystallinefracture

Cracknucleateatsurfaceandgrowacrossseveralgrains(stageI,microcrack),andthentogrowinazigzagmanner(stageII,macrocrack).（）

A:對B:錯

答案:對

Themechanicalpropertyofeachgrainisthesame.（）

A:錯B:對

答案:錯

第三章測試

WhichisnotthecharacteristicofrealfatigueLimit（）

A:FullyreverseduniaxialfatiguetestB:Standard,highlypolished,unnotchedspecimenC:GroupmethodD:Testingfrequencyislargerthan100Hz

答案:Testingfrequencyislargerthan100Hz

ThecharacteristicsofGeneralS-Nbehaviorareasfollows（）

A:S-NcurvesareusuallydrawnthroughmedianlifeB:LessscatterinshorterliferegionC:ElasticbehaviorD:Adiscontinuityor“knee”

答案:S-Ncurvesareusuallydrawnthroughmedianlife;Lessscatterinshorterliferegion;Elasticbehavior;Adiscontinuityor“knee”

Thecorrectconclusionsareasfollows（）

A:ThetensionmeanstressisbeneficialB:ThecompressivemeanstressisdetrimentalC:ThecompressivemeanstressisbeneficialD:Thetensionmeanstressisdetrimental

答案:Thecompressivemeanstressisbeneficial;Thetensionmeanstressisdetrimental

Thiscycliccreepdecreasesthedetrimentaleffectsoftensilemeanstressonfatiguelife.（）

A:錯B:對

答案:錯

Fatiguelimithasrangedfrom1to70percentofultimatetensilestrength.（）

A:對B:錯

答案:對

第四章測試

Whichisnotthecharacteristicofunloading（）

A:ElasticB:ParalleltotheinitialelasticloadinglineC:TheslopeisthemodulusofelasticityD:Permanentdeformation

答案:Permanentdeformation

Thecharacteristicsofhysteresisloopareasfollows（）

A:AreawithinhysteresisloopisenergyperunitvolumedissipatedduringacycleB:Differentstrains,differenthysteresisloopsC:Progressivechangesinthestress-strainbehaviorD:"Lag"phenomenon

答案:Areawithinhysteresisloopisenergyperunitvolumedissipatedduringacycle;Differentstrains,differenthysteresisloops;Progressivechangesinthestress-strainbehavior;"Lag"phenomenon

Thecorrectconclusionsaboutdatafittingareasfollows（）

A:ThestressandplasticstrainamplitudesshouldbetreatedasindependentvariablesB:FatiguelifeasthedependentvariableC:InaccuraciesinmeasuringsmallplasticstrainsatlowloadscaninfluencethetestresultsD:Stressrelaxationisdifferentfromcyclicsoftening

答案:Thestressandplasticstrainamplitudesshouldbetreatedasindependentvariables;Fatiguelifeasthedependentvariable;Inaccuraciesinmeasuringsmallplasticstrainsatlowloadscaninfluencethetestresults;Stressrelaxationisdifferentfromcyclicsoftening

Therateoramountofrelaxationdependsonthemagnitudeofplasticstrainamplitude.（）

A:對B:錯

答案:對

Incremental-steptestmethod:Aseriesofspecimens,eachofwhichissubjectedtoaconstantstrainamplitude.（）

A:錯B:對

答案:錯

第五章測試

Whichisnotthecharacteristicoftypicalloadingmodeorcrackmode（）

A:TearingmodeB:OpeningmodeC:SlidingmodeD:Fatiguefracture

答案:Fatiguefracture

Twostressconditioncontain（）

A:PlanestrainB:AxialloadingC:PlanestressD:Rotatingbending

答案:Planestrain;Planestress

ThelimitingconditionsforLEFMareasfollows（）

A:ThenetnominalstressinthecrackplanemustbelessthantheyieldstrengthB:ShouldbeundercyclicloadingC:TheplasticzonesizeatthecracktipmustbesmallerrelativetothecracklengthD:Theplasticzonesizeatthecracktipmustbesmallerrelativetothegeometricaldimensionsofspecimenorpart

答案:Thenetnominalstressinthecrackplanemustbelessthantheyieldstrength;Theplasticzonesizeatthecracktipmustbesmallerrelativetothecracklength;Theplasticzonesizeatthecracktipmustbesmallerrelativetothegeometricaldimensionsofspecimenorpart

TheincreasingRratiohasatendencytoincreasethecrackgrowthrates.（）

A:對B:錯

答案:對

Thecrackcanbeclosedduringunloadingwhilethespecimenisstillunderapositivetensilestress.（）

A:錯B:對

答案:對

第六章測試

Theincorrectstatementis（）

A:Brittlematerial:thenotcheffectismorepronouncedatshortlivesB:GeometricdiscontinuitiescausestressconcentrationC:NotchedfatiguestrengthonlydependsonthestressconcentrationfactorD:Thecharacteristiclengthdependsonthematerial

答案:Notchedfatiguestrengthonlydependsonthestressconcentrationfactor

ThreeprincipleparametersinHaighdiagramcontain（）

A:NetregionalmeanstressB:NominalstressamplitudeC:NotchfactorD:Tensilestrength

答案:Netregionalmeanstress;Nominalstressamplitude;Notchfactor

ThedescriptionofNeuber’sruleisasfollows（）

A:ThemostwidelyusedmodelB:Relatedstrain-stresscurveisahyperbolaC:PlanestresssituationD:Planestrainsituation

答案:Themostwidelyusedmodel;Relatedstrain-stresscurveisahyperbola;Planestresssituation

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A:對B:錯

答案:對

Thenotchedfatiguestrengthmaybeagreaterfractionofthesmoothfatiguestrength.（）

A:錯B:對

答案:對

第七章測試

TheHigh-temperaturefatigueis（）

A:Below60percentoftheabsolutemeltingtemperatureB:Below50percentoftheabsolutemeltingtemperatureC:Morethan20percentoftheabsolutemeltingtemperatureD:Morethan40percentoftheabsolutemeltingtemperature

答案:Morethan40percentoftheabsolutemeltingtemperature

Temperatureinfluenceonfatiguestrengths（）

A:108cyclesmaybeareasonablevalueforobtainingalong-lifefatiguestrengthB:TemperatureinfluenceissmallC:Thefatiguestrengthcontinuouslydecreases