Fatigue Life Design of Mechanical Structure知到智慧樹章節(jié)測(cè)試課后答案2024年秋北京理工大學(xué)

FatigueLifeDesignofMechanicalStructure知到智慧樹章節(jié)測(cè)試課后答案2024年秋北京理工大學(xué)緒論單元測(cè)試

Excessdeformationis（）

A:LittleplasticityB:StresscorrosioncrackingC:ThemostcommonfailuremodeD:Highenergyabsorption

答案:ThemostcommonfailuremodeThecorrectstatementoffatigueincludes（）

A:Cracknucleation/growthB:Loading,uni/multi-axialloadingC:ConstantorvariableamplitudeD:Repeatedloading

答案:Cracknucleation/growth；Loading,uni/multi-axialloading；Constantorvariableamplitude；RepeatedloadingThecontributionofAugustW?hlerisasfollows（）

A:FatiguelimitB:CorrosionfatigueC:S-NCurveD:Multiplefatigue

答案:Fatiguelimit；S-NCurveFailureduetofatigue,i.e.repeatedloading,isthemostcommoncauseofmechanicalfailure.（）

A:對(duì)B:錯(cuò)

答案:對(duì)Properfatiguedesignincludessynthesis,analysisandtesting.（）

A:錯(cuò)B:對(duì)

答案:對(duì)

第一章單元測(cè)試

Thecharacteristicsoffail-safedesignis（）

A:TheoldestcriterionB:ExpectedmaximumloadorstressoccuroccasionallyC:FracturemechanicsanalysisandtestsD:Ifonepartfails,thesystemdoesnotfail

答案:Ifonepartfails,thesystemdoesnotfailFourkindsofpossibledesignsituationsareasfollows（）

A:ModeldesignB:EquipmentdesignC:ProductdesignD:Designtostandard

答案:Modeldesign；Equipmentdesign；Productdesign；DesigntostandardThemainpointsofdamagetolerancedesignareasfollows（）

A:Anti-crackmeasuresB:HighfracturetoughnessC:MinimumdetectablecracksizeD:Slowcrackpropagation

答案:Anti-crackmeasures；Highfracturetoughness；Minimumdetectablecracksize；SlowcrackpropagationAnalysisneedstobeconfirmedbytests.（）

A:錯(cuò)B:對(duì)

答案:對(duì)Allowableservicelifeshouldbelessthantestorcalculatedlife.（）

A:對(duì)B:錯(cuò)

答案:對(duì)

第二章單元測(cè)試

Whichisnotthecharacteristicofslip（）

A:TherelationshipbetweendislocationsandplasticdeformationB:OccurringwithinindividualgrainsbydislocationmovementC:AsheardeformationofthemetalD:Thesamecharacteristicsundermonotonicloadingandcyclicloading

答案:ThesamecharacteristicsundermonotonicloadingandcyclicloadingThecharacteristicsofbeachmarkareasfollows（）

A:Twoadjacentcracksurfaceswithopen,close,andrubB:WavybandsC:PatternofcrackgrowthD:Crack’sstarting,stoppingandgrowingatdifferentrates

答案:Twoadjacentcracksurfaceswithopen,close,andrub；Wavybands；Patternofcrackgrowth；Crack’sstarting,stoppingandgrowingatdifferentratesModesoffatiguecrackgrowthwithfractureareasfollows（）

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

答案:Inter-crystallinefracture；Trans-crystallinefractureCracknucleateatsurfaceandgrowacrossseveralgrains(stageI,microcrack),andthentogrowinazigzagmanner(stageII,macrocrack).（）

A:對(duì)B:錯(cuò)

答案:對(duì)Themechanicalpropertyofeachgrainisthesame.（）

A:錯(cuò)B:對(duì)

答案:錯(cuò)

第三章單元測(cè)試

WhichisnotthecharacteristicofrealfatigueLimit（）

A:Standard,highlypolished,unnotchedspecimenB:GroupmethodC:FullyreverseduniaxialfatiguetestD:Testingfrequencyislargerthan100Hz

答案:Testingfrequencyislargerthan100HzThecharacteristicsofGeneralS-Nbehaviorareasfollows（）

A:Adiscontinuityor“knee”B:ElasticbehaviorC:S-NcurvesareusuallydrawnthroughmedianlifeD:Lessscatterinshorterliferegion

答案:Adiscontinuityor“knee”；Elasticbehavior；S-Ncurvesareusuallydrawnthroughmedianlife；LessscatterinshorterliferegionThecorrectconclusionsareasfollows（）

A:ThetensionmeanstressisbeneficialB:ThecompressivemeanstressisdetrimentalC:ThetensionmeanstressisdetrimentalD:Thecompressivemeanstressisbeneficial

答案:Thetensionmeanstressisdetrimental；ThecompressivemeanstressisbeneficialThiscycliccreepdecreasesthedetrimentaleffectsoftensilemeanstressonfatiguelife.（）

A:對(duì)B:錯(cuò)

答案:錯(cuò)Fatiguelimithasrangedfrom1to70percentofultimatetensilestrength.（）

A:錯(cuò)B:對(duì)

答案:對(duì)

第四章單元測(cè)試

Whichisnotthecharacteristicofunloading（）

A:ParalleltotheinitialelasticloadinglineB:TheslopeisthemodulusofelasticityC:PermanentdeformationD:Elastic

答案:PermanentdeformationThecharacteristicsofhysteresisloopareasfollows（）

A:"Lag"phenomenonB:Progressivechangesinthestress-strainbehaviorC:AreawithinhysteresisloopisenergyperunitvolumedissipatedduringacycleD:Differentstrains,differenthysteresisloops

答案:"Lag"phenomenon；Progressivechangesinthestress-strainbehavior；Areawithinhysteresisloopisenergyperunitvolumedissipatedduringacycle；Differentstrains,differenthysteresisloopsThecorrectconclusionsaboutdatafittingareasfollows（）

A:InaccuraciesinmeasuringsmallplasticstrainsatlowloadscaninfluencethetestresultsB:FatiguelifeasthedependentvariableC:ThestressandplasticstrainamplitudesshouldbetreatedasindependentvariablesD:Stressrelaxationisdifferentfromcyclicsoftening

答案:Inaccuraciesinmeasuringsmallplasticstrainsatlowloadscaninfluencethetestresults；Fatiguelifeasthedependentvariable；Thestressandplasticstrainamplitudesshouldbetreatedasindependentvariables；StressrelaxationisdifferentfromcyclicsofteningTherateoramountofrelaxationdependsonthemagnitudeofplasticstrainamplitude.（）

A:錯(cuò)B:對(duì)

答案:對(duì)Incremental-steptestmethod:Aseriesofspecimens,eachofwhichissubjectedtoaconstantstrainamplitude.（）

A:錯(cuò)B:對(duì)

答案:錯(cuò)

第五章單元測(cè)試

Whichisnotthecharacteristicoftypicalloadingmodeorcrackmode（）

A:SlidingmodeB:TearingmodeC:FatiguefractureD:Openingmode

答案:FatiguefractureTwostressconditioncontain（）

A:AxialloadingB:PlanestrainC:PlanestressD:Rotatingbending

答案:Planestrain；PlanestressThelimitingconditionsforLEFMareasfollows（）

A:TheplasticzonesizeatthecracktipmustbesmallerrelativetothegeometricaldimensionsofspecimenorpartB:ShouldbeundercyclicloadingC:ThenetnominalstressinthecrackplanemustbelessthantheyieldstrengthD:Theplasticzonesizeatthecracktipmustbesmallerrelativetothecracklength

答案:Theplasticzonesizeatthecracktipmustbesmallerrelativetothegeometricaldimensionsofspecimenorpart；Thenetnominalstressinthecrackplanemustbelessthantheyieldstrength；TheplasticzonesizeatthecracktipmustbesmallerrelativetothecracklengthTheincreasingRratiohasatendencytoincreasethecrackgrowthrates.（）

A:對(duì)B:錯(cuò)

答案:對(duì)Thecrackcanbeclosedduringunloadingwhilethespecimenisstillunderapositivetensilestress.（）

A:錯(cuò)B:對(duì)

答案:對(duì)

第六章單元測(cè)試

Theincorrectstatementis（）

A:NotchedfatiguestrengthonlydependsonthestressconcentrationfactorB:ThecharacteristiclengthdependsonthematerialC:Brittlematerial:thenotcheffectismorepronouncedatshortlivesD:Geometricdiscontinuitiescausestressconcentration

答案:NotchedfatiguestrengthonlydependsonthestressconcentrationfactorThreeprincipleparametersinHaighdiagramcontain（）

A:NetregionalmeanstressB:TensilestrengthC:NominalstressamplitudeD:Notchfactor

答案:Netregionalmeanstress；Nominalstressamplitude；NotchfactorThedescriptionofNeuber’sruleisasfollows（）

A:ThemostwidelyusedmodelB:Relatedstrain-stresscurveisahyperbolaC:PlanestrainsituationD:Planestresssituation

答案:Themostwidelyusedmodel；Relatedstrain-stresscurveisahyperbola；Planestresssituationnull

A:錯(cuò)B:對(duì)

答案:對(duì)Thenotchedfatiguestrengthmaybeagreaterfractionofthesmoothfatiguestrength.（）

A:錯(cuò)B:對(duì)

答案:對(duì)

第七章單元測(cè)試

TheHigh-temperaturefatigueis（）

A:Below60percentoftheabsolutemeltingtemperatureB:Below50percentoftheabsolutemeltingtemperatureC:Morethan40percentoftheabsolutemeltingtemperatureD:Morethan20percentoftheabsolutemeltingtemperature

答案:Morethan40percentoftheabsolutemeltingtemperatureTemperatureinfluenceonfatiguestrengths（）

A:ThefatiguestrengthcontinuouslydecreaseswithcyclestofailureB:TemperatureinfluenceissmallC:Metalsathightemperaturesdonotusuallyshowafatigue