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1、外文文献翻译(含:英文原文及中文译文)英文原文FailureAnalysis,DimensionalDeterminationAndAnalysis,ApplicationsOfCamsINTRODUCTIONItisabsolutelyessentialthatadesignengineerknowhowandwhypartsfailsothatreliablemachinesthatrequireminimummaintenancecanbedesigned.Sometimesafailurecanbeserious,suchaswhenatireblowsoutonanautomobi
2、letravelingathighspeed.Ontheotherhand,afailuremaybenomorethananuisance.Anexampleisthelooseningoftheradiatorhoseinanautomobilecoolingsystem.Theconsequenceofthislatterfailureisusuallythelossofsomeradiatorcoolant,aconditionthatisreadilydetectedandcorrected.Thetypeofloadapartabsorbsisjustassignificanta
3、sthemagnitude.Generallyspeaking,dynamicloadswithdirectionreversalscausegreaterdifficultythanstaticloads,andtherefore,fatiguestrengthmustbeconsidered.Anotherconcerniswhetherthematerialisductileorbrittle.Forexample,brittlematerialsareconsideredtobeunacceptablewherefatigueisinvolved.Manypeoplemistakin
4、glyinterpretthewordfailuretomeantheactualbreakageofapart.However,adesignengineermustconsiderabroaderunderstandingofwhatappreciabledeformationoccurs.Aductilematerial,howeverwilldeformalargeamountpriortorupture.Excessivedeformation,withoutfracture,maycauseamachinetofailbecausethedeformedpartinterfere
5、swithamovingsecondpart.Therefore,apartfails(evenifithasnotphysicallybroken)wheneveritnolongerfulfillsitsrequiredfunction.Sometimesfailuremaybeduetoabnormalfrictionorvibrationbetweentwomatingparts.Failurealsomaybeduetoaphenomenoncalledcreep,whichistheplasticflowofamaterialunderloadatelevatedtemperat
6、ures.Inaddition,theactualshapeofapartmayberesponsibleforfailure.Forexample,stressconcentrationsduetosuddenchangesincontourmustbetakenintoaccount.Evaluationofstressconsiderationsisespeciallyimportantwhentherearedynamicloadswithdirectionreversalsandthematerialisnotveryductile.Ingeneral,thedesignengin
7、eermustconsiderallpossiblemodesoffailure,whichincludethefollowing.——Stress——Deformation——Wear——Corrosion——Vibration——Environmentaldamage——LooseningoffasteningdevicesThepartsizesandshapesselectedalsomusttake