已阅读5页,还剩8页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
3附录附录1英文原文Reflectionsregardinguncertaintyofmeasurement,ontheresultsofaNordicfatiguetestinterlaboratorycomparisonMagnusHolmgren,ThomasSvensson,ErlandJohnson,KlasJohanssonAbstractThispaperpresentstheexperiencesofcalculationandreportinguncertaintyofmeasurementinfatiguetesting.SixNordiclaboratoriesperformedfatiguetestsonsteelspecimens.Thelaboratoriesalsoreportedtheirresultsconcerninguncertaintyofmeasurementandhowtheycalculatedit.Theresultsshowlargedifferencesinthewaytheuncertaintiesofmeasurementwerecalculatedandreported.Nolaboratoryincludedthemostsignificantuncertaintysource,bendingstress(duetomisalignmentofthetestingmachine,“incorrect”specimensand/orincorrectlymountedspecimens),whencalculatingtheuncertaintyofmeasurement.SeverallaboratoriesdidnotcalculatetheuncertaintyofmeasurementinaccordancewiththeGuidetotheExpressionofUncertaintyinMeasurement(GUM)1.Keyword:Uncertaintyofmeasurement,Calculation,Report,Fatiguetest,LaboratoryintercomparisonDefinitions:RStressratioFmin/FmaxFForce(nektons)AandBFatiguestrengthparameterssandSStress(megapascals)NNumberofcycles.IntroductionThecorrectorbestmethodofcalculatingandreportinguncertaintyofmeasurementintestinghasbeenthesubjectofdiscussionformanyyears.TheissuebecameevenmorerelevantinconnectionwiththeintroductionofISOstandards,e.g.ISO170252.Thediscussion,aswellasimplementationoftheuncertaintyofmeasurementconcept,hasoftenbeenconcentratedonwhichequationtouseoronadministrativehandlingoftheissue.Therehasbeenlessinterestinthetechnicalproblemandhowtohandleuncertaintyofmeasurementintheactualexperimentalsituation,andhowtolearnfromtheuncertaintyofmeasurementcalculationwhenimprovingtheexperimentaltechnique.Onereasonforthismaybethattheaccreditationbodieshaveconcentratedontheveryexistenceofuncertaintyofmeasurementcalculationsforanaccreditedtestmethod,insteadofonwhetherthecalculationsareperformedinasoundtechnicalway.Thepresentinvestigationemphasizestheneedforamoretechnicalfocus.Onetestingareawhereitisdifficulttodouncertaintyofmeasurementcalculationsisfatiguetesting.However,thereisguidanceonhowtoperformsuchcalculations,e.g.inRefs.3,4.Toinvestigatehowuncertaintyofmeasurementcalculationsareperformedforfatiguetestsinreallife,UTMIS(theSwedishfatiguenetwork)startedaninterlaboratorycomparisonwhereone4ofthemostessentialpartswastocalculateandreporttheuncertaintyofmeasurementofatypicalfatiguetestthatcouldhavebeenorderedbyacustomeroftheparticipatinglaboratories.Forcostreasons,customersoftenaskforalimitednumberoftestspecimensbut,atthesametime,theyrequestalotofinformationaboutalargeportionofthepossiblestress-lifeareafromfewcycles(highstresses)tomillionsofcycles(lowstresses)andevenrun-outs.Thewaythecalculationwasmadeshouldalsobereported.Theoutcomeconcerningtheuncertaintyofmeasurementfromtheprojectisreportedinthisarticle.ParticipantsSixNordiclaboratoriesparticipatedintheinterlaboratorycomparison:oneindustriallaboratory,tworesearchinstitutes,twouniversitylaboratoriesandonelaboratoryinaconsultancycompany.Twoofthelaboratoriesareaccreditedforfatiguetesting,andathirdlaboratoryisaccreditedforothertests.Eachparticipantwasrandomlyassignedanumberbetween1and6,andthisnotificationwillbeusedintherestofthispaper.ExperimentalprocedureTheparticipantsreceivedinformationaboutthetestspecimens(withoutmaterialdata),togetherwithinstructionsonthewaytoperformthetestandhowtoreporttheresults.Theinstructionswerethattestsshouldbeperformedasconstantloadamplitudetests,withR=0.1atthreedifferentstresslevels,460,430and400Map,withfourspecimensateachstresslevel,atatestfrequencybetween10and30Hz,witharun-outlimitat6510cyclesandinanormallaboratoryclimate(0203Cand5015%relativehumidity).Thiswasconsideredasatypicalcustomerorderedtest.Thetestresultsweretobeusedtocalculateestimatesofthetwofatiguestrengthparameters,AandB,accordingtolinearregressionofthelogsandlongvariables,i.e.loglogABN.ThereportedresultshouldincludeboththeestimatedparametersAandBandtheuncertaintiesinthemduetomeasurementerrors.Thereportshouldalsoincludetheconsiderationsandcalculationsbehindtheresults,especiallythoseconcerninguncertaintyofmeasurement.Severalpropertiesweretobereportedforeachspecimen.Themostimportantonewasthenumberofcyclesuntilfractureorifthespecimenwasarun-out(i.e.survivedfor6510cycles).ThetestsweretobeperformedinaccordancewithASTME-466965andISO5725-26.ASTME-466-96doesnottakeuncertaintyofmeasurementintoaccount;However,ASTME-466-96mentionsthatthebendingstressintroducedowingtomisalignmentmustnotexceed5%ofthegreateroftherange,maximumorminimumstresses.Therearealsorequirementsfortheaccuracyofthedimensionalmeasurementofthetestspecimen.Allparticipantsusedhydraulictestingmachines.Thetestspecimensweremadeofsteel(yieldstress375390Map,andtensilestrength670690Map,tabulatedvalues).Thetestspecimensweredistributedtotheparticipantsbytheorganizer.Results5TheprimarylaboratoryresultsthatshouldbecomparedaretheestimatedWhalercurves.Inordertopresentallresultsinthesameway,theorganizertransformedsomeoftheresults.TheWhalercurvesreportedbytheparticipantsareshowninFig.1.Itcanbeseenthatthereareconsiderabledifferencesbetweenlaboratories.Anapproximatestatisticaltestshowsasignificantlaboratoryeffect.MaterialscatteralonecannotexplainthedifferencesintheWhalercurves.Inordertoinvestigateifthelaboratoryeffectwassolelycausedbythemodelinguncertainty,weestimatednewparametersfromtherawdatawithacommonalgorithm.Wethenchosetouseonlythefailedspecimensandtomaketheminimizationinthelogarithmiclifedirection.TheresultsareshowninFig.2.Aformalstatisticalsignificancetestwasthenmade,andtheresultofsuchatestshowsthatthedifferencesbetweenthelaboratoriesshowninFig.1couldbeattributedonlytomodeling.UncertaintyofmeasurementcalculationsOneofthemostimportantobjectiveswiththisinvestigationwastocomparetheobserveddifferencesbetweenlaboratorytestresultswiththeirestimateduncertaintiesofmeasurement.Theintentionwastoanalyzetheuncertaintyanalysesassuch,andtocomparethemtothestandardprocedurerecommendedintheISOguide:GuidetotheExpressionofUncertaintyinMeasurement(GUM)1.Thelaboratoriesidentifieddifferentsourcesofuncertaintyandtreatedthemindifferentways.Thesesourcesaretheloadmeasurement,theloadcontrol,thesuperimposedbendingstressesbecauseofmisalignmentandthedimensionalmeasurements.Implicitly,laboratorytemperatureandhumidity,specimentemperatureandcorrosioneffectsarealsoconsidered.Inaddition,theresultsshowamodelingeffect.ThedifferentlaboratorytreatmentsofthesesourcesaresummarizedinTable1.SpecificcommentsonthedifferentlaboratoriesAlllaboratoriesgavetheirlaboratorytemperatureandhumidity,butdidnotconsiderthesevaluesassourcesofuncertainty,i.e.theinfluenceoftemperatureandhumiditywasneglected.Thisconclusionisreasonableforsteelinthetemperaturerangeandhumidityrangeinquestion7.Laboratory1.Theuncertaintyduetotheappliedstresswasdeterminedtakingloadcellanddimensionaluncertaintiesintoaccount.ThemathematicalevaluationwasmadeinaccordancewiththeGUM.Specimentemperaturewasmeasured,butwasimplicitlyneglected.Themodelingproblemwasmentioned,butnotconsideredasanuncertaintysource.Laboratory2.Thereportcontainsnouncertaintyevaluation.Theuncertaintiesintheloadcellandthemicrometerareconsidered,butneglectedwithreferencetothelargematerialscatter.Specimentemperaturewasmeasured.Modelingproblemsarementionedbyacommentregardingthechoiceofloadlevels.Laboratory3.Thereportcontainsnouncertaintyevaluation.However,theaccuracyofthe6machineisgivenandtheloadwascontrolledduringtheteststobewithinspecifiedlimits.Thebendingstressesweremeasuredononespecimen,buttheirinfluenceonthefatigueresultwasnottakenintoconsideration.Laboratory4.Theuncertaintiesintheloadcellandthedimensionalmeasurementsareconsideredinanevaluationofstressuncertainty.ThemethodfortheevaluationisnotinaccordancewiththeGUMmethod,butwasperformedbyaddingabsoluteerrors.Thebendingstressinfluenceandthecontrolsystemdeviationsareconsidered,butnotincludedintheuncertaintyevaluation.Thefailurecriterionismentionedandregardedasnegligible,andcorrosionismentionedasapossiblesourceofuncertainty.Laborat
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 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,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 短语专题市公开课一等奖省赛课微课金奖课件
- 我的一家人品德与生活市公开课一等奖省赛课微课金奖课件
- 高中生物一轮总复习第5讲细胞中的糖类脂质和无机物必修省公开课一等奖新名师获奖课件
- unit5travellingabroad1市公开课一等奖省赛课微课金奖课件
- 湖北荆门达标名校2024届中考物理押题试卷含解析
- 黑龙江省肇源县重点中学2024届中考化学全真模拟试题含解析
- 复习8量子物理省公开课金奖全国赛课一等奖微课获奖课件
- 高考政治复习第一部分第三单元收入与分配第七课个人收入的分配市赛课公开课一等奖省名师获奖课
- unit5DO-you-want-to-watch-a-game-show市公开课一等奖省赛课微课金
- 高考英语复习-Unit-18-Beauty-选修科目市赛课公开课一等奖省名师获奖课件
- 交通标志安装现场质量施工记录表
- 2021年湖北省中小学教师水平能力测试题 2021教师水平能力测试题.doc
- 研究生联合培养协议书
- 柔性版印刷机操作说明
- 年产200吨蜂王浆冻干粉、蜂花粉工厂设计
- 慌慌张张的莎莎幻灯片
- 雨水泵站设计说明书
- 国内外水嘴标准的主要技术要求
- 企业分立的会计和税务处理
- 中考物理专题计算题复习课件.ppt
- 二年级数学下册1000以内数的认识练习
评论
0/150
提交评论