会员注册 | 登录 | 微信快捷登录 支付宝快捷登录 QQ登录 微博登录 | 帮助中心 人人文库renrendoc.com美如初恋!
站内搜索 百度文库

热门搜索: 直缝焊接机 矿井提升机 循环球式转向器图纸 机器人手爪发展史 管道机器人dwg 动平衡试验台设计

   首页 人人文库网 > 资源分类 > DOC文档下载

外文翻译--破损钢板在热矫直过程中的原理.doc

  • 资源星级:
  • 资源大小:474.00KB   全文页数:18页
  • 资源格式: DOC        下载权限:注册会员/VIP会员
您还没有登陆,请先登录。登陆后即可下载此文档。
  合作网站登录: 微信快捷登录 支付宝快捷登录   QQ登录   微博登录
友情提示
2:本站资源不支持迅雷下载,请使用浏览器直接下载(不支持QQ浏览器)
3:本站资源下载后的文档和图纸-无水印,预览文档经过压缩,下载后原文更清晰   

外文翻译--破损钢板在热矫直过程中的原理.doc

HEATSTRAIGHTENINGDAMAGEDSTEELPLATEELEMENTSByR.RichardAvent,1DavidJ.Mukai,2PaulF.Robinson,3andRandyJ.Boudreaux4ABSTRACTThefundamentalelementofanystructuralsteelshapeistheflatplate.Damagetobridgestructuresconsistsoftheseplateelements,incombination,bentabouttheirstrongand/orweakaxes.Thepurposeofthispaperistodescribeexperimentalandanalyticalresearchonheatstraighteningasappliedtoplatesandtopresentrelatedengineeringcriteriaforitsuse.Anexperimentalprogramwasconductedtoevaluatetheresponseofplatestoheatstraighteningandtoidentifyimportantparametersinfluencingbehavior.Over300heatswereappliedtoavarietyofplates.Theprimaryfactorsinfluencingstraighteningweretheangleoftheveeheat,steeltemperatureduringheating,andexternalrestrainingforces.Theplasticrotationafterheatingwasdirectlyproportionaltotheseparameters.Toaidengineersinpredictingplatemovementsduringheatstraightening,asimplemathematicalformulawasdeveloped.Thisequationrelatestheaverageplasticrotationperveeheattoveeangle,steeltemperature,magnitudeofrestrainingforce,coefficientofthermalexpansion,andyieldstress.Theformulacompareswelltotheexperimentaldataandisthefirstsimpleformulaavailablethatincludestheparametersofheatingtemperatureandmagnitudeofrestrainingforce.Theformofthisanalyticalapproachalsowilllenditselftowardextensions,includingthebehaviorofrolledshapes,axiallyloadedmembers,andcompositeandnoncompositegirders.INTRODUCTIONThefundamentalelementofanystructuralsteelshapeistheflatplate.Damagetobridgestructuresconsistsoftheseplateelements,incombination,bentabouttheirstrongand/orweakaxes.Thepurposeofthispaperistodescribeexperimentalandanalyticalresearchonheatstraighteningasappliedtoplatesandtopresentrelatedengineeringdesigncriteriaforitsuse.Thisworkformsthebasisforextensionstoheatstraighteningofrolledshapes.Severaldetailedstudieshavebeenconductedforveeheatsappliedtoplates.Theveeheatistheusualheatingpatternforstraighteningplatesbentabouttheirstrongaxisandisexplainedindetailinalatersection.Thesestudieshaveattemptedtoidentifyparametersthatinfluenceveeheatsandtodeveloppredictivemodelsbasedonthisdata.NichollsandWeerth1972describedthebendsproducedby211veeheatswhoseapexanglevariedfrom247to607in67incrementsappliedto10mm3/8in.thickA36steelplate.Theveedepthwasalsovariedoverfulldepth,threefourthdepth,andonehalfdepth.Noattemptwasmadetoevaluatetheeffectoftheseparametersotherthanthegeneralresultthatthegreatertheveeangleanddepth,thegreaterthebendproduced.Roeder1986alsoconductedastudyonundamagedveeheatedplates.Heemployedsophisticatedmonitoringequipmentsuchasthermocouples,contactpyrometers,andstraingauges,aswellasmoreconventionaltoolssuchasverniercaliperandasteelruler.Hisworkisparticularlysignificantasthefirstattempttobothexperimentallyandanalyticallyquantifyheatstraighteningbehaviorforplatesoverawiderangeofparameters.Theparametersincludedveegeometry,specimengeometry,heatingtemperatureandrate,steelgrade,restrainingforce,initialresidualstresses,andquenching.Roedersconclusionswerebasedonapproximately60heatsoverawiderangeofparameters.Asaresulttherewererelativelyfewrepetitiveheatsusingidenticalparameters.Althoughtrendscouldbedrawnfromthisdata,itssparsenesslimitedthequantitativevalueoftheresults.However,hisresearchprovidedtheinitialbasisformuchoftheexperimentalworkreportedhere.RoedersmostsignificantconclusionswereApracticalandsafeupperheatingtreatmentlimitis6507C1,2007F.Changesinmaterialpropertiesaresmallwhentheheatingtemperatureremainsbelowthephasetransitiontemperatureofapproximately7207C1,3307F.Therotationproducedbyaveeheatisdirectlyproportionaltoveeangleandheatingtemperature.Therotationproducedbyaveeheatisdirectlyproportionaltorestrainingforcesthatproducecompressionintheopenendoftheveeduringheating.Quenchingiseffectiveandmayincreaseveeheatrotations,butheatingtemperaturesshouldbekeptbelowthephasetransitiontemperaturealthoughsomepractitionersrecommendquenchingonlyifthesteeltemperatureisbelow7007For3707C.Plasticstrainoccursprimarilywithintheveeheatregion.Plasticstrainissomewhatsensitivetogeometryoftheplate.However,muchofthissensitivitycanbeattributedtodifferencesinrateofheatingandheatflow.TheresearchdescribedinthispaperextendsRoedersworkandincludesenoughrepetitivedatapointstoquantifytheseandotherconclusions.LiteratureonheatstraighteninghasbeenavailableformanyyearsasreviewedinastateoftheartpaperbyAvent1989.However,engineeringquantificationoftheprocesshasbeenlacking.Thehandfulofpractitionerscurrentlyusingthemethodrelyextensivelyontheirmanyyearsofexperiencetoguidethemthrougharepair.Anengineerlackingthiswealthofexperienceneedsasetofanalyticalprocedurestodeterminehowbesttoapplytheheatstraighteningprocesstoaparticularrepair.Theseanalyticaltools,forreasonsofeconomy,shouldberelativelyfast,easytoapply,andallowforsuchconsiderationsasdifferentveegeometries,temperatureranges,externalloadings,andsupportrestraints.Atpresent,twoextremesexist1OverlysimplisticmodelsHolt1965,1971Moberg1979thatcannottakeintoaccounttheeffectofeithertemperaturevariationsorinternalandexternalrestraintand2comprehensivecomputermodelsForChin1962Burbank1968Weerth1971Horton1973Roeder1985,1986,1987basedonelasticplasticfiniteelementorfinitestripstressanalysiscombinedwithasimilarthermalanalysis.Whereastheformeristoosimplistictoaccuratelypredictbehavior,thelatterrequiressuchlengthycomputationaleffortastonotbepracticalfordesignofficeuse.Asaresult,thereisaneedforananalyticalmodelthatoffersbothpracticalityandcomprehensiveinclusionofallimportantvariablestoaccuratelypredictbehavior.Animportantconsiderationnotincludedinthemoresimpleformulationsistheinfluenceofexternalandinternalrestrainingforces.Externalforcestypicallyareappliedtoproducebendingmomentstendingtostraightenthemember.Theexternalforces,producingcompressionontheopenendoftheveeduringheating,willincreasetheavailableconfinementand,therefore,increasetherotationproducedperheat.ThefieldapplicationscitedbybothHoltandMoberginvolvedtheuseofrestrainingforces.Becauseinmostcasesthematerialrestraintalonewillbelessthanperfectconfinement,itseemslikelythatanycorrelationbetweenthepredictedandactualmovementinthestructuresbeingrepaired,asnotedbybothHoltandMoberg,isprimarilyduetotheinfluenceoftheexternalforces.Animprovedanalyticalmodelshouldincludetheeffectsofbothinternalandexternalrestraints.Thepurposeofthispaperistoquantifytheparametersinfluencingtheheatstraighteningofplateelementsandtodevelopsimpleyetefficientproceduresforpredictingtheresponseofdeformedsteelplatesduringtheheatstraighteningprocess.Theapproachchosenwastofirstidentifyallparametersthathaveanimportantinfluenceontheheatstraighteningprocess.Thisphasewasaccomplishedbystudyingtheexperimentaldataavailablefrompreviousresearchaswellasbyconductinganextensiveexperimentalprogramtoprovideadditionaldata.Aftersynthesizingthisexperimentaldata,ananalyticalprocedureforpredictingmemberresponsewasdeveloped.EVALUATIONOFRESULTSOFEXPERIMENTALPROGRAMVeeAngleResearchersagreethatoneofthemostfundamentalparametersinfluencingtheplasticrotationofaplateistheveeangleHolt1971Roeder1986Avent1989.Thedatashowsafairlylinearrelationshipbetweenplasticrotationandveeangle.Forthisreason,mostdatawillbeplottedwiththeveeangleastheordinateandplasticrotationwpastheabscissa.Afirstorderleastsquarescurvefitwillsometimesbeshown.Plotsinsucceedingsectionsshowaconsistentproportionalrelationshipbetweenthesevariables.DepthofVeePastresearchersHolt1971Roeder1985haveconcludedthattheplasticrotationisproportionaltothedepthratioRd,whichistheratioofveedepthdvtoplatewidthW.AreviewofRoederstestdataintherangeof6507C68071,2007F61507isinconclusiveastoveedeptheffect.Recognizingthatthedatawassparse,neitherthedepthratioof0.75nor0.67producedplasticrotationsthatwereconsistentlyhiearchial.Tofurtherevaluatethisbehavior,aseriesoftestswasconductedfordepthratiosof0.5,0.75,and1.0andveeanglesrangingfrom207to607.Atleastthreeheatswereconductedoninitiallystraightplatesforeachcaseandtheresultsaveraged.TheresultsareshowninFig.2foracombinationofthreedepthratios,threeveeangles,andtwojackingratios.Thejackingratiosreflectthatajackingforcewasusedtocreateamomentattheveeheatzoneequaltoeither25or50oftheultimatebendingcapacityoftheplate.AscanbeseenfromFig.2,thedepthratiosof75and100trackeachotherwell.Infactthe75depthratioresultedinslightlylargerplasticrotationsinallbutoneofthesixcases.The50depthratioresultedinanerraticbehaviorwhencomparedtotheothertwo.Inthreeofthesixcasesthe50depthratioproducedmuchsmallerplasticrotations.Intheotherthreecases,theplasticrotationsweresimilar.Tofurtherverifythisbehavior,aseriesofplateswasdamagedandstraightened.Thedegreeofdamagewaslargeenoughthatatleast20heatswererequiredformostoftheseplates.Therefore,morestatisticallysignificantaverageplasticrotationswereobtainedfromthesetests.ResultsarecomparedinFig.3forajackingratioof0.5andtwoveedepthratios,0.75and1.0.Againthepatternofplasticrotationsdoesnothaveadirectcorrelationtotheveedepthratios.Therefore,althoughitwouldseemintuitivethatincreasingtheveedepthwouldincreasetheplasticrotation,thereisnoexperimentaljustificationforsuchageneralstatement.Itcanbeconcludedthatthevariationofveedepthratiosbetween0.75and1.0haslittleinfluenceonplasticrotation.However,aveedepthratioof50mayreducetheplasticrotations.PlateThicknessandWidthResearchershavegenerallyconsideredplatethicknesstohaveanegligibleeffectonplasticrotation.Theonlyreservationhasbeenexpressedthattheplateshouldbethinenoughtoallowarelativelyuniformpenetrationoftheheatthroughthethickness.

注意事项

本文(外文翻译--破损钢板在热矫直过程中的原理.doc)为本站会员(英文资料库)主动上传,人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对上载内容本身不做任何修改或编辑。 若此文所含内容侵犯了您的版权或隐私,请立即通知人人文库网([email protected]),我们立即给予删除!

温馨提示:如果因为网速或其他原因下载失败请重新下载,重复下载不扣分。

copyright@ 2015-2017 人人文库网网站版权所有
苏ICP备12009002号-5