影响耐久性强度的因素-机械设计及制造专业毕业设计外文翻译-中英文对照.doc
上传人:天马****23 上传时间:2024-09-12 格式:DOC 页数:18 大小:408KB 金币:10 举报 版权申诉
预览加载中,请您耐心等待几秒...

影响耐久性强度的因素-机械设计及制造专业毕业设计外文翻译-中英文对照.doc

影响耐久性强度的因素-机械设计及制造专业毕业设计外文翻译-中英文对照.doc

预览

免费试读已结束,剩余 8 页请下载文档后查看

10 金币

下载此文档

如果您无法下载资料,请参考说明:

1、部分资料下载需要金币,请确保您的账户上有足够的金币

2、已购买过的文档,再次下载不重复扣费

3、资料包下载后请先用软件解压,在使用对应软件打开

本科生毕业论文(设计)第页共NUMPAGES18页外文翻译FACTORSAFFECTINGTHEENDURANCESTRENGTHPublisheddataforendurancestrengtharedeterminedbyspecialfatiguetestingdevices,whichtypicallyuseapolishedspecimensubjectedtoareversedbendingload,similarthatsketchedinfigure.Iftheactualoperatingconditionsofapartinamachinearedifferent.andtheyusuallyare,thefaiguestrengthmustbereducedfromthereportedvalue.Someofthefactorsthatdecreasetheendurancestrengtharediscussednext.Thisdiscussionrelatestotheendurancestrengthformaterialssubjectedonlytotensilenormalstresses,thatis,tensilestressesresultingfrombendingactionsoraxialtension.Casesinvolvingfluctuatingtorsionalshearstressesarediscussedseparately.Fatiguefailuresaremostlikelytooccurinregionsofhightensilestressratherthancompressivestress.SizeofthesectionThetestspecimenisusually0.30inch(7.6mm)indiameter.Largersectionsizesexhibitlowerstrengths,havealessfavorablestressdistribution,andhavelessuniformityofproperties,particularlywithheat-treatedparts.Reference1includesasuggestedmethodofdetermingthesizefactorforrotatingshaftsupto10.0inches(250mm)indiameter.Wewillusethatmethodherealsobecausewearebasingouranalysisonthereversedbendingphenomenon.Tableshowsthesuggestedrelationshipsfordetermingasizefactor,tobeappliedtotheendurancestrengthtoaccountforthesizeofthecrosssection.FigureshowsplotsoftheequationsfromTable,withsomeblendingofthecurves,Readingfromthecurvesshouldprovideacceptableaccuracy.Whenthecomponentbeingdesignedisnotcircularlikeashaft,judgmentisrequiredtodeterminethecharacteristicdimensiontouseintheformulas.Forflat,rolledshapes,thethicknessshouldbeused.Notedthattheuseoftheseequationsisapproximate.SurfaceFinishAnydeviationfromapolishedsurfacereducesendurancestrength.Figureshowsroughestimatesfortheendurancestrengths,comparedwiththeultimatetensilestrengthofsteelsforseveralpracticalsurfaceconditions,Itiscriticalthatpartssubjectedtofatigueloadingbeprotectedfromnicks,scratches,andcorrosionbecausetheydrasticallyreducefatiguestrength.StressConcentrationsSudd
立即下载