Fundamentals-of-Reliability-Engineering-Revised

©2010EatonCorporation.Allrightsreserved.FundamentalofRMEngineering可靠性和可维修性工程概论REV.01IvanFeng2012.4.2022©2009EatonCorporation.Allrightsreserved.Content
Introductiontoreliabilityengineering
ReliabilityMetricsExplained
Reliabilityindesign
ReliabilityPrediction,Modeling,andAnalysis
ReliabilityTestingandDataAnalysis
IntroductiontoMaintainability
MaintainabilityPrediction33©2009EatonCorporation.Allrightsreserved.ReliabilityperCustomerPerspectiveCustomerViewpointAvailabilityStaticQualityCharacteristicsFunctionPerformanceReliabilityMaintainabilityRepairabilityServiceabilityDelayTimeLogisticsTimeAdministrativeTime44©2009EatonCorporation.Allrightsreserved.Un-ReliabilityCostsTypicallyVisibleCostsDirectReplacementCostsWarranty-FieldReplacementsTypicallyHiddenCostsIndirectProductServiceSparePartInventoryEngineeringSupportConcessionsRecallsLostSalesLostCustomersLiability&LegalImpacttoCompanyReputation55©2009EatonCorporation.Allrightsreserved.IntroductiontoreliabilityengineeringWhatisreliability/可靠性的定义“Reliabilityistheprobabilityofaproductperformingitsintendedfunctionoveritsspecifiedperiodofusage,andunderspecifiedoperatingconditions,inamannerthatmeetsorexceedscustomerexpectations.”
Qualityisdefinedas“Conformancetospecifications”
Reliabilityinitssimplestformisdefinedas“Qualityovertime”.
Reliabilityisgenerallyconcernedwithfailuresduringlifeofaproduct.通常品质可定义为符合规格,可靠性可简单理解为”一直符合规格”可靠性通常关注的是产品生命周期中可能出现的失效.66©2009EatonCorporation.Allrightsreserved.QualityVS.ReliabilityQualityReliabilityConformancetorequirementsatthestartofuseHowmanyoftheseunitsstillmeetspecificationsafteraweek/month/yearofoperation?QualityisasnapshotatthestartoflifeReliabilityisamotionpictureoftheday-by-dayoperationTimezerodefectsaremanufacturingmistakesthatescapedfinaltestTheadditionaldefectsthatappearovertimeare“reliabilitydefects”FractiondefectiveFractiondefectivevs.timeReliabilityisQualityovertime77©2009EatonCorporation.Allrightsreserved.IntroductiontoreliabilityengineeringThepatternoffailure/失效的定义
Totallossofintendedfunction/功能完全丧失
Partial/Degradedintendedfunction/功能部分丧失或退化
Intermittentintendedfunction/间歇性功能丧失
Unintendedfunction/出现不期望的功能
Hiddenunintendedfunction/潜在的不期望的功能88©2009EatonCorporation.Allrightsreserved.IntroductiontoreliabilityengineeringTheBathtubCurve/浴缸曲线WearOutTimeFailureRatePoorQuality•Badparts•Assemblyproblems•Mfg.processproblems•Designweakness•Example:tireblowoutduetoMfg.defectStressstrength•Unexpectedexternalevents-customerabuse-accident-voltagesurge•Consequentialdamage•Environment•Example:tireblowoutduetopotholeNormalWear•Fatigue•Abrasion/wear•Creep•Relaxation•Lifetestingrequired•Historicaldata•Example:tiretreadwearoutInfantMortalityb1NormalOperationb=1b1DecreasingFailureRatebadregionConstantFailureRatedesiredregionIncreasingFailureRatebadregion99©2009EatonCorporation.Allrightsreserved.IntroductiontoreliabilityengineeringTheBathtubCurveVS.stress-strength环境负荷环境负荷环境负荷环境负荷产品强度产品强度产品强度产品强度失效率失效率失效率失效率浴缸曲线浴缸曲线浴缸曲线浴缸曲线老化老化老化老化瑕疪品瑕疪品瑕疪品瑕疪品时间T0时间T1时间T2负荷负荷负荷负荷----强度强度强度强度1010©2009EatonCorporation.Allrightsreserved.Content
Introductiontoreliabilityengineering
ReliabilityMetricsExplained
Reliabilityindesign
ReliabilityPrediction,Modeling,andAnalysis
ReliabilityTestingandDataAnalysis
IntroductiontoMaintainability
MaintainabilityPrediction1111©2009EatonCorporation.Allrightsreserved.ReliabilityMathematicsReliabilityMeasures/可靠度衡量指标
Reliability(R(t)):thereliabilityofaproductoveraspecifiedperiodoftimet./可靠度
MeanTimeBetweenFailure(MTBForMTTF):meantimebetweenfailuresforrepairablesystem./平均无故障时间
PercentilesofLife(BxLife):lifeofaproductatwhichx%failed
CumulativeFailureRate(F(t)):probabilitythataproductwillfailbeforereachingoperatingtimet./累积失效率/不可靠度
InstantaneousFailureRate(h(t)):rateoffailureatanygivensmalltimeperiod./瞬时失效率
FailureRate(λ):numberoffailuresdividedbycumulativeoperatingtime./平均失效率1212©2009EatonCorporation.Allrightsreserved.ReliabilityR(t)
产品在规定条件下使用时间t后,还能完成规定功能的概率,被定义为产品的”可靠度”.R(t)=P(Tt),式中t为使用时间,T为故障出现时间,P表示不出现故障的概率.
可靠度的估计方法:当同型号的N个产品作为样品总数,当N足够大的情况下,产品的可靠度的估计值为:R(t)=[N-n(t)]/N,N为样品总数,n(t)为t时刻点的失效总数用来评估一批产品随时间变化的可靠性评估一批产品工作一段时间后还能继续工作的能力表示一大批产品的统计特性,而不能表示个别产品或少数产品的可靠性e.g.一台安装在户外使用的太阳能逆变器使用1年不出故障的概率为99%,那么我们可以说其可靠度R(1year)=0.991313©2009EatonCorporation.Allrightsreserved.ExampleofR(t)有80台SolarInverter安装到一个太阳能发电厂使用,收集整理其故障数据如下:TimeNo.10~40032400~800183800~12002641200~16001551600~2000962000~2400672400~2800282800~32001R(0)=1R(400)=77/80=0.963R(800)=0.738R(1200)=0.413R(1600)=0.225R(2000)=0.113R(2400)=0.075R(2800)=0.013R(3300)=000.10.20.30.40.50.60.70.80.91040080012001600200024002800320036001414©2009EatonCorporation.Allrightsreserved.MeanTimeBetweenFailureMTBF(ForRepairablesystems):Thecumulativeoperatingtimedividedbythenumberoftimesanitemfails,isrepaired,andisreturnedtoservice.Example:Afarmmachineryengineisrepaired8timesandisreturnedtoserviceoveritslife.Itprovidesatotalof50,000hrsofservice.hrs6,2508hrs50,000FailuresofNumberTimeOperatingTotalMTBF===MTTF(ForNon-Repairablesystems):Thecumulativeoperatingtimedividedbythenumberoffailuresforagro