1、BSI Standards Publication Optical fibres Reliability Power law theory PD IEC/TR 62048:2014National foreword This Published Document is the UK implementation of IEC/TR 62048:2014. It supersedes PD IEC/TR 62048:2011 which is withdrawn. The UK participation in its preparation was entrusted by Technical
2、 Committee GEL/86, Fibre optics, to Subcommittee GEL/86/1, Optical fibres and cables. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
3、its correct application. The British Standards Institution 2014. Published by BSI Standards Limited 2014 ISBN 978 0 580 82512 5 ICS 33.180.10 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published under the authority of the Standards P
4、olicy and Strategy Committee on 28 February 2014. Amendments/corrigenda issued since publication Date Text affected PUBLISHED DOCUMENT PD IEC/TR 62048:2014 IEC TR 62048 Edition 3.0 2014-01 TECHNICAL REPORT Optical fibres Reliability Power law theory INTERNATIONAL ELECTROTECHNICAL COMMISSION XB ICS 3
5、3.180.10 PRICE CODE ISBN 978-2-8322-1369-8 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publication from an authorized distributor. colour inside PD IEC/TR 62048:2014 2 TR 62048 IEC:2014(E) CONTENTS FOREWORD . 5 INTRODUCTION . 7 1 Sc
6、ope 8 2 Normative references 8 3 Symbols 8 4 General approach 10 5 Formula types 10 6 Measuring parameters for fibre reliability . 11 6.1 Overview 11 6.2 Length and equivalent length . 11 6.3 Reliability parameters 12 6.3.1 Overview 12 6.3.2 Proof-testing . 12 6.3.3 Static fatigue 12 6.3.4 Dynamic f
7、atigue 13 6.4 Parameters for the low-strength region 13 6.4.1 Overview 13 6.4.2 Variable proof test stress 13 6.4.3 Dynamic fatigue 14 6.5 Measured numerical values 17 7 Examples of numerical calculations . 17 7.1 Overview 17 7.2 Failure rate calculations . 18 7.2.1 FIT rate formulae 18 7.2.2 Long l
8、engths in tension . 18 7.2.3 Short lengths in uniform bending 20 7.3 Lifetime calculations 22 7.3.1 Lifetime formulae 22 7.3.2 Long lengths in tension . 22 7.3.3 Short lengths in uniform bending 23 7.3.4 Short lengths with uniform bending and tension 25 8 Fibre weakening and failure . 26 8.1 Crack g
9、rowth and weakening . 26 8.2 Crack fracture 28 8.3 Features of the general results 29 8.4 Stress and strain 30 9 Fatigue testing . 30 9.1 Overview 30 9.2 Static fatigue 30 9.3 Dynamic fatigue . 32 9.3.1 Overview 32 9.3.2 Fatigue to breakage 32 9.3.3 Fatigue to a maximum stress 34 9.4 Comparisons of
10、static and dynamic fatigue 34 9.4.1 Intercepts and parameters obtained 34 9.4.2 Time duration . 34 PD IEC/TR 62048:2014TR 62048 IEC:2014(E) 3 9.4.3 Dynamic and inert strengths . 35 9.4.4 Plot non-linearities 36 9.4.5 Environments 36 10 Proof-testing 37 10.1 Overview 37 10.2 The proof test cycle . 37
11、 10.3 Crack weakening during proof-testing 38 10.4 Minimum strength after proof-testing 39 10.4.1 Overview 39 10.4.2 Fast unloading 39 10.4.3 Slow unloading . 40 10.4.4 Boundary condition . 41 10.5 Varying the proof test stress 41 11 Statistical description of strength by Weibull probability models
12、. 41 11.1 Overview 41 11.2 Strength statistics in uniform tension 41 11.2.1 Unimodal probability distribution . 41 11.2.2 Bimodal probability distribution . 43 11.3 Strength statistics in other geometries . 43 11.3.1 Stress non-uniformity 43 11.3.2 Uniform bending . 44 11.3.3 Two-point bending 45 11
13、.4 Weibull analysis for static fatigue before proof-testing 45 11.5 Weibull analysis for dynamic fatigue before proof-testing . 47 11.6 Weibull distribution after proof-testing 49 11.7 Weibull analysis for static fatigue after proof-testing 51 11.8 Weibull analysis for dynamic fatigue after proof-te
14、sting 53 12 Reliability prediction 54 12.1 Reliability under general stress and constant stress . 54 12.2 Lifetime and failure rate from fatigue testing 55 12.3 Certain survivability after proof-testing . 56 12.4 Failures in time 57 13 B-value: elimination from formulae, and measurements . 58 13.1 O
15、verview 58 13.2 Approximate Weibull distribution after proof-testing . 58 13.2.1 Overview 58 13.2.2 “Risky region“ during proof-testing 58 13.2.3 Other approximations . 59 13.3 Approximate lifetime and failure rate 61 13.4 Estimation of the B-value . 62 13.4.1 Overview 62 13.4.2 Fatigue intercepts .
16、 62 13.4.3 Dynamic fatigue failure stress . 62 13.4.4 Obtaining the strength 62 13.4.5 Stress pulse measurement . 63 13.4.6 Flaw growth measurement 63 PD IEC/TR 62048:2014 4 TR 62048 IEC:2014(E) Annex A (informative) Statistical strength degradation map 64 Bibliography 65 Figure 1 Weibull dynamic fa
17、tigue plot near the proof test stress level . 16 Figure 2 Instantaneous FIT rates of 1 km fibre versus time for applied stress/proof test stress percentages (bottom to top): 10 %, 15 %, 20 %, 25 %, 30 % 19 Figure 3 Averaged FIT rates of 1 km fibre versus time for applied stress/proof test stress per
18、centages (bottom to top): 10 %, 15 %, 20 %, 25 %, 30 % 19 Figure 4 Instantaneous FIT rates of bent fibre with 1 m effective length versus time 21 Figure 5 Averaged FIT rates of bent fibre with 1 m effective length versus time for bend diameters (top to bottom): 10 mm, 20 mm, 30 mm, 40 mm, 50 mm . 21
19、 Figure 6 1 km lifetime versus failure probability for applied stress/proof test stress percentages (top to bottom): 10 %, 15 %, 20 %, 25 %, 30 % . 23 Figure 7 Lifetimes of bent fibre with 1 m effective length versus failure probability for bend diameters (bottom-right to top-left): 10 mm, 20 mm, 30
20、 mm, 40 mm, 50 mm . 24 Figure 8 Static fatigue Applied stress versus time for a particular applied stress . 31 Figure 9 Static fatigue Schematic data of failure time versus applied stress 32 Figure 10 Dynamic fatigue Applied stress versus time for a particular applied stress rate 32 Figure 11 Dynami
21、c fatigue Schematic data of failure time versus applied stress rate 34 Figure 12 Proof-testing Applied stress versus time 38 Figure 13 Static fatigue schematic Weibull plot 47 Figure 14 Dynamic fatigue schematic Weibull plot 48 Figure A.1 Schematic diagram of the statistical strength degradation map
22、 . 64 Table 1 Symbols 8 Table 2 FIT rates of 1 km fibre in Figures 2 and 3 at various times 20 Table 3 FIT rates of 1 metre effective length bent fibre in Figures 4 and 5 at various times 22 Table 4 FIT rates of Table 3 neglecting stress versus strain non-linearity. 22 Table 5 1 km lifetimes in year
23、s of Figure 6 for various failure probabilities . 23 Table 6 Lifetimes of bent fibre with 1 metre effective length in years of Figure 7 for various failure probabilities 24 Table 7 Lifetimes in years of Table 6 neglecting stress versus strain non-linearity . 245 Table 8 Calculated results in case of
24、 bend plus 30 % of proof test tension for 30 years 26 PD IEC/TR 62048:2014TR 62048 IEC:2014(E) 5 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ OPTICAL FIBRES Reliability Power law theory FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization com
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36、shed as an International Standard, for example “state of the art“. IEC/TR 62048, which is a technical report, has been prepared by subcommittee 86A: Fibres and cables, of IEC technical committee 86: Fibre optics. This third edition cancels and replaces the second edition published in 2011, and const
37、itutes a technical revision. The main changes with respect to the previous edition are listed below: correction to the unit of failure rates in Table 1; PD IEC/TR 62048:2014 6 TR 62048 IEC:2014(E) correction to the FIT equation for instantaneous failure rate 19 1in addition to all call-outs and deri
38、vations; insertion of a new note about fibre length dependency of failure rates; addition of informative Annex A and relevant reference; editorial corrections of inconsistencies. The text of this technical report is based on the following documents: Enquiry draft Report on voting 86A/1537/DTR 86A/15
39、54/RVC Full information on the voting for the approval of this technical report can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. The committee has decided that the contents of this publication will
40、 remain unchanged until the stability 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, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may
41、 be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer. _ 1Numbers in squa
42、re brackets refer to the Bibliography. PD IEC/TR 62048:2014TR 62048 IEC:2014(E) 7 INTRODUCTION Reliability is expressed as an expected lifetime or as an expected failure rate. The results cannot be used for specifications or for the comparison of the quality of different fibres. This technical repor
43、t develops the theory behind the experimental principles used in measuring the fibre parameters needed in the reliability formulae. Much of the theory is taken from the referenced literature and is presented here in a unified manner. The primary results are formulae for lifetime or for failure rate,
44、 given in terms of the measurable parameters. Conversely, an allowed maximum service stress or extreme value of another parameter may be calculated for an acceptable lifetime or failure rate. For readers interested only in the final results of this technical report a summary of the formulae used and
45、 numerical examples in the calculation of fibre reliability Clauses 6 and 7 are sufficient and self-contained. Readers wanting a detailed background with algebraic derivations will find this in Clauses 8 to 12. An attempt is made to unify the approach and the notation to make it easier for the reade
46、r to follow the theory. Also, it should ensure that the notation is consistent in all test procedures. The Bibliography has a limited set of mostly theoretical references, but it is not necessary to read them to follow the analytical development in this technical report. Annex A introduces a statist
47、ical strength degradation (SSD) map which gives intuitive understanding of the physical meaning of the formulae appearing in Clauses 10 and 11. NOTE Clauses 8 to 12 reference the B-value, and this is done for theoretical completeness only. There are as yet no agreed methods for measuring B, so the B
48、ibliography gives only a brief analytical outline of some proposed methods and furthermore develops theoretical results for the special case in which B can be neglected. PD IEC/TR 62048:2014 8 TR 62048 IEC:2014(E) OPTICAL FIBRES Reliability Power law theory 1 Scope This technical report is a guideli
49、ne that gives formulae to estimate the reliability of fibre under a constant service stress based on a power law for crack growth. NOTE Power law is derived empirically, but there are other laws which have a more physical basis (for example, the exponential law). All these laws generally fit short-term experimental data well but lead to different long-term predictions. The power law has been selected as a most reasonable
