ASD-STAN PREN 3745-410-2014 Aerospace series Fibres and cables optical aircraft use Test methods Part 410 Thermal life (Edition P 2).pdf

1、ASD-STAN STANDARD NORME ASD-STAN ASD-STAN NORM prEN 3745-410 Edition P 2 March 2014 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Rue Montoyer 10 - 1000 Brussels - Tel. 32 2 775 8126 - Fax. 32 2 775 8131 - www.asd-stan.org ICS: Supersedes edition P 1 of Se

2、ptember 2006 and will supersede EN 3745-410:2007 Descriptors: ENGLISH VERSION Aerospace series Fibres and cables, optical, aircraft use Test methods Part 410: Thermal life Srie arospatiale Fibres et cbles optiques usage aronautique Mthodes dessais Partie 410 : Dure de vie en temprature Luft- und Rau

3、mfahrt Faseroptische Leitungen fr Luftfahrzeuge Prfverfahren Teil 410: Lebensdauer unter Temperatureinwirkung This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for

4、 the needs of the European Aerospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically

5、 or functionally, without re-identification of the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (

6、EN). The CEN national members have then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 1st March 2014 Comments should be sent within six months after the date

7、 of publication to ASD-STAN Electrical Domain Copyright 2014 by ASD-STAN prEN 3745-410:2014 (E) 2 Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Test specimens 3 3.1 Fibre ends . 3 4 Method A (without mechanical stress applied) 3 4.1 Preparation of test specimens . 3 4.2 Test conditio

8、ns 4 4.3 Apparatus . 4 4.4 Procedure . 4 5 Method B (with mechanical stress applied) 5 5.1 Preparation of test specimens . 5 5.2 Test conditions 5 5.3 Information to be included in the product standard 5 5.4 Apparatus . 6 5.5 Procedure . 7 6 Requirements . 9 Foreword This standard was reviewed by th

9、e Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Publication. prEN 3745-410:2014 (E) 3 1 Scope This standard specifies a m

10、ethod of measuring the thermal endurance of a finished optical cable. There are two test methods incorporated which estimate the cables thermal life with or without the cable. Method A without mechanical stress (temperature only), Method B combined temperature and mechanical stress. 2 Normative refe

11、rences The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

12、EN 2591-100, Aerospace series Elements of electrical and optical connection Test methods Part 100: General EN 3745-100, Aerospace series Fibres and cables, optical, aircraft use Test methods Part 100: General EN 3745-301, Aerospace series Fibres and cables, optical, aircraft use Test methods Part 30

13、1: Attenuation ASTM-D3032, Standard test methods for hookup wire insulation 1) 3 Test specimens 3.1 Fibre ends The fibre ends shall be prepared in accordance with EN 2591-100. If not yet at standard test conditions, the specimens shall be subjected to standard test conditions and stabilized at these

14、 conditions for 24 h as defined in EN 3745-100. 4 Method A (without mechanical stress applied) 4.1 Preparation of test specimens Specimens have to be fixed on an apparatus representative of aircraft installation. Ten specimens are fixed on apparatus and constitute a set for life testing at each temp

15、erature. A minimum of four sets of specimens is necessary. 1) Published by: ASTM National (US) American Society for Testing and Materials http:/www.astm.org/ prEN 3745-410:2014 (E) 4 4.2 Test conditions The following details shall be specified if not already included in the product standard: Type of

16、 fibre/cable from which the specimens were taken, Type/number/pitch of clamps Minimum authorized long term bend radius Length of specimens if not 10 m Maximum permissible variation in attenuation if not 3 dB Temperature values (1 2 3 4) 4.3 Apparatus The apparatus shall comprise: A Light Launch Syst

17、em (LLS) as defined in EN 2591-100, A split coupler 1 10, A Light Detection System (LDS) as defined in EN 2591-100, with 10 channel recorder, A fixture to secure the specimens, A climatic chamber capable of temperature control of 2 C. 4.4 Procedure 4.4.1 Initial measurements If the value of the high

18、est temperature value is not specified in the product standard make a quick estimation of the highest test temperature with one specimen during 24 h at 80 C above the nominal rating temperature. The variation in attenuation shall not exceed the specified value. 4.4.2 Test The attenuation shall be mo

19、nitored throughout the test in accordance with EN 3745-301, method C. Connect the specimen ends to the coupler, the coupler to LLS and the other specimen ends to LDS. Place the fixture in the test chamber. The coupler and connectors shall not be into climatic chamber. Begin the test sequence with th

20、e highest test temperature (1) since exposure times will be relatively short. Record the exposure time to failure for each specimen. A failure is defined when the variation in attenuation is higher than the specified value. Stop the test sequence when all specimens in group have failed. Calculate th

21、e log average life as defined in ASTM-D3032. If the log average life at this temperature (highest) is found to be less than 100 h, too high a test temperature has been selected and these data should be discarded. Tests should be repeated at lower temperature. prEN 3745-410:2014 (E) 5 Repeat this pro

22、cedure with the group N 2 of specimens for 2 temperature value. Calculate the log average life as defined in ASTM-D3032. Repeat this procedure with the group N 3 of specimens for 3 temperature value. Calculate the log average life as defined in ASTM-D3032. Repeat this procedure with the last group o

23、f specimens for 4 temperature value (lowest). Calculate the log average life as defined in ASTM-D3032. If the average life found at this test temperature is less than 5 000 h, this test will be made at lower temperature. 4.4.3 Final measurements and requirement The calculation of average life and ex

24、trapolation have defined in the ASTM-D3032 - Standard test methods for hookup wire insulation. 4.4.4 Special precautions Extrapolation to a temperature index expected at the selected end of life (10 000 h, 20 000 h or 40 000 h) should not exceed 25 C below the lowest aging test temperature. The log

25、average life at the highest test temperature (1) shall not be less than 100 h. The log average life at the lowest test temperature (4) shall not be less than 5 000 h. 5 Method B (with mechanical stress applied) 5.1 Preparation of test specimens One set for life testing shall consist of ten specimens

26、 fixed on the apparatus (Figure 1) at each temperature. A minimum of four sets of specimens is necessary. In order to reduce the variation of stress to the fibre the cable shall be attached to the test fixture by trapping it between two padded plates rather than using standard aircraft cable clamps.

27、 5.2 Test conditions Length of specimens 5 m. Length of specimens within the test chamber 3 m. Maximum permissible variation in attenuation if not 3 dB at 20 C 3 C and at 850 nm. Launch conditions to be 85/85. 5.3 Information to be included in the product standard Type of fibre/cable from which the

28、specimens were taken, Minimum long term bend radius (R), wave length if not 850 nm, Maximum permissible variation in attenuation if not 3 dB, Launch conditions if not 85/85. prEN 3745-410:2014 (E) 6 5.4 Apparatus The apparatus shall comprise: A Light Launch System (LLS) as defined in EN 2591-100, A

29、Light Detection System (LDS) as defined in EN 2591-100, A device allowing to connect the LLS to all specimen shall be used to focus the test on the ageing of cable, A device allowing measuring one of the specimens or all cable without disconnection shall be used in order to keep the baseline of init

30、ial measurement. A test fixture to secure the specimens, this fixture shall be so designed that the cable is mounted so that it can be bent at 90 either side of its centre line and is free to freely follow a curve between the two clamp points that corresponds to it minimum bend radius (D 2R). The te

31、st sample is to be so arranged that only the portion of the sample in the flexing area is stressed during the test. The fixtures corner is to be rounded and padded see Figures 1 and 2. A climatic chamber capable of temperature control of 2 C. Key 1 To the LLS 2 To the LDS 3 Fixed plate 4 Moving plat

32、e D is twice the cable minimum bend radius R not less than the minimum bend radius least Figure 1 Test Fixture prEN 3745-410:2014 (E) 7 Key 1 Plate 2 Cable 3 Silicon rubber foam Figure 2 Fixture radius and padded edges 5.5 Procedure 5.5.1 Initial measurements If the highest test temperature value is

33、 not specified in the product standard make an evaluation of the highest test temperature with one specimen during 24 h at 80 C above the nominal rating temperature. This evaluation needs to be done at temperatures below the degradation temperature of raw materials used in the cable under test. The

34、jacket shall not fail or the variation in attenuation shall not exceed the specified value in which case repeat the test at a lower temperature. 5.5.2 Test The attenuation shall be measured at the end of each exposure cycle in accordance with EN 3745-301, method C. Connect the specimen ends to the L

35、LS and the other specimen ends to LDS during all the cycles. Place the fixture in the test chamber. The connectors shall not be in the climatic chamber. Measure the attenuation of each test specimen. Begin the test sequence with the highest test temperature (1) since exposure times will be relativel

36、y short. Expose the specimens for the first test cycle. NOTE This measurement is for reference only and does not form part of the qualification testing. To monitor the behaviour of the cable/s under test at high temperature, an attenuation measurement of each cable shall be made at the maximum point

37、 of the high temperature cycle immediately prior to reducing the temperature to ambient. On completion of the exposure period allow the specimen to return to ambient. Bend the specimen to 90o once in each direction then return the specimen to the neutral position before measuring the attenuation val

38、ue. Inspect the cable jacket in the bend area for major cracks or splits without disturbing the cable. prEN 3745-410:2014 (E) 8 Start the next exposure cycle. Record the number of exposure cycles to failure for each specimen. A failure is defined when the variation in attenuation is higher than the

39、specified value or the jacket splits or cracks. The life of each specimen is defined as the number of cycles to failure times the length of each cycle. Stop the test sequence when all specimens in the set have failed. Calculate the log average life as defined in ASTM-D3032. If the log average life a

40、t this temperature (highest) is found to be less than 100 h, too high a test temperature has been selected and these data should be discarded. Tests should be repeated at lower temperature. Repeat this procedure with the group N 2 of specimens for 2 temperature value. Calculate the log average life

41、as defined in ASTM-D3032. Repeat this procedure with the group N 3 of specimens for 3 temperature value. Calculate the log average life as defined in ASTM-D3032. If the calculated regression line does not indicate a life of less than 40 000 h at a temperature less than 30 C below the test temperatur

42、e repeat this procedure with another group of specimens at temperature not greater than 30 C above the calculated 40 000 h temperature. 5.5.3 Calculation of the regression line It has been established that many materials deteriorate in a manner so that the following equation applies: L Ae b/K where

43、L is the insulation life; K is the absolute temperature (in kelvins); A, b are constants for each insulation; e is the base of natural logarithms. Equation may be expressed as a linear function by taking logarithms: log L log A b/K Let Y log L a log A X 1/K Then Y a bX prEN 3745-410:2014 (E) 9 Thus,

44、 data from testing at higher temperatures may be plotted on log L versus 1/K graph paper and a line extrapolated to lower temperatures. However, since the nature of logarithmic plots does not allow accurate extrapolation by the method of drawing the best apparent straight line through the data point

45、s, a more rigorous method has to be used for greater accuracy and uniformity. By the use of the method of least squares, the constants and b may be derived in terms of the experimental data obtained. These equations are as follows: a ( (YX) c(Y)/( cn) X) b (Y an) / X c X2/X where X 1/K is the recipr

46、ocal of the test temperature, K (C 273); n is the number of end points used in the calculation; Y log L is the logarithm of the average life at each test point; is the summation of n values. Knowing the constants a and b, the slope of the regression line is readily found by use of equation: Y a bX K

47、 1/X b/(Y a) For example Temperature at 20 000 h (in C) b/(4.301 0 a) 273 Temperature at 2 000 h (in C) b/(3.301 0 a) 273 5.5.4 Special precautions Extrapolation to a temperature index expected at the selected end of life (10 000 h, 20 000 h or 40 000 h) should not exceed 30 C below the lowest aging

48、 test temperature. For longer life times this may be exceeded provided that the plot demonstrates a minimum of 40 000 h at 30 C below the lowest ageing test temperature. The log average life at the highest test temperature (1) shall not be less than 100 h. The log average life at the lowest test temperature (4) shall not be less than 5 000 h. The exposure cycle length is defined as too short if the group average if the mean number of cycles to failure exceeds 15 cycles. 6 Requirements The required lifetime and temperature shall be given in the product standard.