Fatigue Life Design of Mechanical Structure智慧樹知到答案章節(jié)測試2023年北京理工大學(xué)

緒論單元測試Excessdeformationis（）

A:Stresscorrosioncracking

B:Littleplasticity

C:Highenergyabsorption

D:Themostcommonfailuremode

答案:DThecorrectstatementoffatigueincludes（）

A:Loading,uni/multi-axialloading

B:Cracknucleation/growth

C:Repeatedloading

D:Constantorvariableamplitude

答案:ABCDThecontributionofAugustW?hlerisasfollows（）

A:Multiplefatigue

B:S-NCurve

C:Fatiguelimit

D:Corrosionfatigue

答案:BCFailureduetofatigue,i.e.

repeatedloading,isthemostcommoncauseofmechanicalfailure.（）

A:錯

B:對

答案:BProperfatiguedesignincludessynthesis,analysisandtesting.（）

A:對

B:錯

答案:A第一章測試Thecharacteristicsoffail-safedesignis（）

A:Ifonepartfails,thesystemdoesnotfail

B:Fracturemechanicsanalysisandtests

C:Theoldestcriterion

D:Expectedmaximumloadorstressoccuroccasionally

答案:AFourkindsofpossibledesignsituationsareasfollows（）

A:Equipmentdesign

B:Productdesign

C:Designtostandard

D:Modeldesign

答案:ABCDThemainpointsofdamagetolerancedesignareasfollows（）

A:Highfracturetoughness

B:Slowcrackpropagation

C:Anti-crackmeasures

D:Minimumdetectablecracksize

答案:ABCDAnalysisneedstobeconfirmedbytests.（）

A:錯

B:對

答案:BAllowableservicelifeshouldbelessthantestorcalculatedlife.（）

A:對

B:錯

答案:A第二章測試Whichisnotthecharacteristicofslip（）

A:Thesamecharacteristicsundermonotonicloadingandcyclicloading

B:Occurringwithinindividualgrainsbydislocationmovement

C:Therelationshipbetweendislocationsandplasticdeformation

D:Asheardeformationofthemetal

答案:AThecharacteristicsofbeachmarkareasfollows（）

A:Twoadjacentcracksurfaceswithopen,close,andrub

B:Patternofcrackgrowth

C:Crack’sstarting,stoppingandgrowingatdifferentrates

D:Wavybands

答案:ABCDModesoffatiguecrackgrowthwithfractureareasfollows（）

A:Trans-crystallinefracture

B:Dislocationmovement

C:Inter-crystallinefracture

D:Slipdeformation

答案:ACCracknucleateatsurfaceandgrowacrossseveralgrains(stageI,microcrack),andthentogrowinazigzagmanner(stageII,macrocrack).（）

A:錯

B:對

答案:BThemechanicalpropertyofeachgrainisthesame.（）

A:錯

B:對

答案:A第三章測試WhichisnotthecharacteristicofrealfatigueLimit（）

A:Fullyreverseduniaxialfatiguetest

B:Standard,highlypolished,unnotchedspecimen

C:Testingfrequencyislargerthan100Hz

D:Groupmethod

答案:CThecharacteristicsofGeneralS-Nbehaviorareasfollows（）

A:Elasticbehavior

B:S-Ncurvesareusuallydrawnthroughmedianlife

C:Lessscatterinshorterliferegion

D:Adiscontinuityor“knee”

答案:ABCDThecorrectconclusionsareasfollows（）

A:Thecompressivemeanstressisbeneficial

B:Thetensionmeanstressisdetrimental

C:Thecompressivemeanstressisdetrimental

D:Thetensionmeanstressisbeneficial

答案:ABThiscycliccreepdecreasesthedetrimentaleffectsoftensilemeanstressonfatiguelife.（）

A:錯

B:對

答案:AFatiguelimithasrangedfrom1to70percentofultimatetensilestrength.（）

A:對

B:錯

答案:A第四章測試Whichisnotthecharacteristicofunloading（）

A:Theslopeisthemodulusofelasticity

B:Paralleltotheinitialelasticloadingline

C:Elastic

D:Permanentdeformation

答案:DThecharacteristicsofhysteresisloopareasfollows（）

A:Progressivechangesinthestress-strainbehavior

B:Differentstrains,differenthysteresisloops

C:Areawithinhysteresisloopisenergyperunitvolumedissipatedduringacycle

D:“Lag”phenomenon

答案:ABCDThecorrectconclusionsaboutdatafittingareasfollows（）

A:Stressrelaxationisdifferentfromcyclicsoftening

B:Fatiguelifeasthedependentvariable

C:Thestressandplasticstrainamplitudesshouldbetreatedasindependentvariables

D:Inaccuraciesinmeasuringsmallplasticstrainsatlowloadscaninfluencethetestresults

答案:ABCDTherateoramountofrelaxationdependsonthemagnitudeofplasticstrainamplitude.（）

A:錯

B:對

答案:BIncremental-steptestmethod:Aseriesofspecimens,eachofwhichissubjectedtoaconstantstrainamplitude.（）

A:對

B:錯

答案:B第五章測試Whichisnotthecharacteristicoftypicalloadingmodeorcrackmode（）

A:Openingmode

B:Tearingmode

C:Slidingmode

D:Fatiguefracture

答案:DTwostressconditioncontain（）

A:Planestress

B:Rotatingbending

C:Axialloading

D:Planestrain

答案:ADThelimitingconditionsforLEFMareasfollows（）

A:Thenetnominalstressinthecrackplanemustbelessthantheyieldstrength

B:Theplasticzonesizeatthecracktipmustbesmallerrelativetothecracklength

C:Shouldbeundercyclicloading

D:Theplasticzonesizeatthecracktipmustbesmallerrelativetothegeometricaldimensionsofspecimenorpart

答案:ABDTheincreasingRratiohasatendencytoincreasethecrackgrowthrates.（）

A:錯

B:對

答案:BThecrackcanbeclosedduringunloadingwhilethespecimenisstillunderapositivetensilestress.（）

A:錯

B:對

答案:B第六章測試Theincorrectstatementis（）

A:Thecharacteristiclengthdependsonthematerial

B:Brittlematerial:thenotcheffectismorepronouncedatshortlives

C:Geometricdiscontinuitiescausestressconcentration

D:Notchedfatiguestrengthonlydependsonthestressconcentrationfactor

答案:DThreeprincipleparametersinHaighdiagramcontain（）

A:Nominalstressamplitude

B:Tensilestrength

C:Netregionalmeanstress

D:Notchfactor

答案:ACDThedescriptionofNeuber’sruleisasfollows（）

A:Themostwidelyusedmodel

B:Planestresssituation

C:Planestrainsituation

D:Relatedstrain-stresscurveisahyperbola

答案:ABDnull

A:對

B:錯

答案:AThenotchedfatiguestrengthmaybeagreaterfractionofthesmoothfatiguestrength.（）

A:錯

B:對

答案:B第七章測試TheHigh-temperaturefatigueis（）

A:Below60percentoftheabsolutemeltingtemperature

B:Below50percentoftheabsolutemeltingtemperature

C:Morethan20percentoftheabsolutemeltingtemperature

D:Morethan40percentoftheabsolutemeltingtemperature

答案:DTemperatureinfluenceonfatiguestrengths（）

A:108cyclesmaybeareasonablevalueforobtainingalong-lifefatiguestr