IEC 61649-2008 Weibull analysis《Weibull分析》.pdf

1、 IEC 61649Edition 2.0 2008-08INTERNATIONAL STANDARD NORME INTERNATIONALEWeibull analysis Analyse de Weibull IEC61649:2008THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2008 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or u

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16、 de Weibull INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE XBICS 03.120.01; 03.120.30 PRICE CODECODE PRIXISBN 2-8318-9954-0 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale 2 6164

17、9 IEC:2008 CONTENTS FOREWORD.5INTRODUCTION.71 Scope.82 Normative references .83 Terms, definitions, abbreviations and symbols83.1 Terms and definitions 83.2 Abbreviations 103.3 Symbols 104 Application of the techniques115 The Weibull distribution 115.1 The two-parameter Weibull distribution115.2 The

18、 three-parameter Weibull distribution .136 Data considerations136.1 Data types.136.2 Time to first failure 136.3 Material characteristics and the Weibull distribution 136.4 Sample size 136.5 Censored and suspended data 147 Graphical methods and goodness-of-fit 147.1 Overview .147.2 How to make the p

19、robability plot147.2.1 Ranking.157.2.2 The Weibull probability plot .157.2.3 Dealing with suspensions or censored data .157.2.4 Probability plotting.177.2.5 Checking the fit .177.3 Hazard plotting188 Interpreting the Weibull probability plot.198.1 The bathtub curve .198.1.1 General .198.1.2 1 Implie

20、s wear-out.208.2 Unknown Weibull modes may be “masked“208.3 Small samples.218.4 Outliers .228.5 Interpretation of non-linear plots228.5.1 Distributions other than the Weibull .258.5.2 Data inconsistencies and multimode failures .259 Computational methods and goodness-of-fit .259.1 Introduction .259.

21、2 Assumptions and conditions 269.3 Limitations and accuracy.269.4 Input and output data 2661649 IEC:2008 3 9.5 Goodness-of-fit test.279.6 MLE point estimates of the distribution parameters and .279.7 Point estimate of the mean time to failure289.8 Point estimate of the fractile (10 %) of the time to

22、 failure.289.9 Point estimate of the reliability at time t (t T).289.10 Software programs 2810 Confidence intervals.2810.1 Interval estimation of 2810.2 Interval estimation of .2910.3 MRR Beta-binomial bounds .3010.4 Fishers Matrix bounds 3010.5 Lower confidence limit for B10.3110.6 Lower confidence

23、 limit for R 3111 Comparison of median rank regression (MRR) and maximum likelihood (MLE) estimation methods 3111.1 Graphical display.3111.2 B life estimates sometimes known as B or L percentiles 3111.3 Small samples.3211.4 Shape parameter 3211.5 Confidence intervals3211.6 Single failure .3211.7 Mat

24、hematical rigor.3211.8 Presentation of results 3212 WeiBayes approach3312.1 Description3312.2 Method3312.3 WeiBayes without failures .3312.4 WeiBayes with failures 3312.5 WeiBayes case study 3413 Sudden death method 3514 Other distributions 37Annex A (informative) Examples and case studies .38Annex

25、B (informative) Example of computations 40Annex C (informative) Median rank tables42Annex D (normative) Statistical Tables 47Annex E (informative) Spreadsheet example48Annex F (informative) Example of Weibull probability paper.55Annex G (informative) Mixtures of several failure modes56Annex H (infor

26、mative) Three-parameter Weibull example.59Annex I (informative) Constructing Weibull paper.61Annex J (informative) Technical background and references64Bibliography67Figure 1 The PDF shapes of the Weibull family for = 1,0 .12Figure 2 Total test time (in minutes).16Figure 3 Typical bathtub curve for

27、an item .19 4 61649 IEC:2008 Figure 4 Weibull failure modes may be “masked” .21Figure 5 Sample size: 10 .21Figure 6 Sample size: 100 .22Figure 7 An example showing lack of fit with a two-parameter Weibull distribution .23Figure 8 The same data plotted with a three-parameter Weibull distribution show

28、s a good fit with 3 months offset (location 2,99 months).24Figure 9 Example of estimating t0by eye .25Figure 10 New compressor design WeiBayes versus old design 35Figure A.1 Main oil pump low times38Figure A.2 Augmenter pump bearing failure .39Figure A.3 Steep values hide problems .39Figure B.1 Plot

29、 of computations .41Figure E.1 Weibull plot for graphical analysis.49Figure E.2 Weibull plot of censored data51Figure E.3 Cumulative hazard plot for data of Table E.4 52Figure E.4 Cumulative hazard plots for Table E.6 54Figure H.1 Steel-fracture toughness Curved data59Figure H.2 t0improves the fit o

30、f Figure H.1 data 60Table 1 Guidance for using this International Standard 11Table 2 Ranked flare failure rivet data .15Table 3 Adjusted ranks for suspended or censored data 16Table 4 Subgroup size to estimate time to X % failures using the sudden death method .36Table 5 Chain data: cycles to failur

31、e 36Table B.1 Times to failure 40Table B.2 Summary of results 41Table D.1 Values of the gamma function47Table D.2 Fractiles of the normal distribution .47Table E.1 Practical analysis example.48Table E.2 Spreadsheet set-up for analysis of censored data 50Table E.3 Example of Weibull analysis for susp

32、ended data50Table E.4 Example of Spreadsheet application for censored data 51Table E.5 Example spreadsheet.52Table E.6 A relay data provided by ISO/TC94 and Hazard analysis for failure mode 1 .53Table I.1 Construction of ordinate (Y).62Table I.2 Construction of abscissa (t).62Table I.3 Content of da

33、ta entered into a spreadsheet.6261649 IEC:2008 5 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ WEIBULL ANALYSIS FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees).

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43、C Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61649 has been prepared by IEC technical committee 56: Dependability. This second edition cancels and replaces the first edition, published i

44、n 1997, and constitutes a technical revision. The main changes with respect to the previous edition are as follows: the title has been shortened and simplified to read “Weibull analysis”; provision of methods for both analytical and graphical solutions have been added. The text of this standard is b

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46、1649 IEC:2008 The committee has decided that the contents of this publication will remain unchanged until the maintenance result date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the specific publication. At this date, the publication will be reconfirmed, withdr

47、awn, replaced by a revised edition, or amended. 61649 IEC:2008 7 INTRODUCTION The Weibull distribution is used to model data regardless of whether the failure rate is increasing, decreasing or constant. The Weibull distribution is flexible and adaptable to a wide range of data. The time to failure,

48、cycles to failure, mileage to failure, mechanical stress or similar continuous parameters need to be recorded for all items. A life distribution can be modelled even if not all the items have failed. Guidance is given on how to perform an analysis using a spreadsheet program. Guidance is also given

49、on how to analyse different failure modes separately and identify a possible weak population. Using the three-parameter Weibull distribution can give information on time to first failure or minimum endurance in the sample. 8 61649 IEC:2008 WEIBULL ANALYSIS 1 Scope This International Standard provides methods for analysing data from a W