1、 STD-BSI BS EN 2155-12-ENGL 1777 1b24bb7 b57437 72T BRITISH STANDARD AEROSPACE SERIES Test methods for transparent materials for aircraft glazing Part 12. Determination of linear thermal expansion The European Standard EN 215512 : 1997 has the status of a British Standard ICs 49.025.W; 49.045 NO COP
2、YING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BS EN 2155-12 : 1997 BS EN 2155-12 : 1997 Amd. No. National foreword Date Text affected This British Standard is the English hguage version of EN 215512 : 1997. The UK participation in its preparation was entrusted to Technical Committ
3、ee ACW62, Aerospace structural transparencies and non-reinforced plastics, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible European committee any enquiries on the interpretation, or proposais for change, and keep the LJK interests informed - moni
4、tor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this docu
5、ment may be found in the BSI Standards Catalogue under the section entitled International Standards Correspondence Index, or by using the Find facility of the BSI Standards Electronic Catalogue. NOTE. Under the AECMA part numbering system, normative references to the Parts of AECMA- originated Europ
6、ean Standards may appear in clause 2 in the form of a threedigit number e.g. -001 where the BSI and CEN systems would use the form -1. It can be assumed that, wherever referenced, the threedigit and single digit fonns can be used interchangeably. For the purposes of part-marking of components produc
7、ed in accordance with this standard, the threedigit form should be used. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 6, an inside back cover
8、and a back cover. This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 16 November 1997 O BSI 1997 ISBN O 580 28134 6 _ STD-BSI BS EN 2155-12-ENGL 1777 9 lb24bb7 Ob57441 388
9、D EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2155-12 July 1997 ICs 49.025.4C Descriptors: aircraft industry, glazing, materials, transparency, plastics. tests, determination, thermal properties, thermal expansion English version Aerospace series - Test methods for transparent materials for
10、 aircraft glazing - Part 12: Determination of linear thermal expansion Srie arospatiale - Mthodes dessais pour matriaux transparents pour vitrages aronautiques - Partie 12: Dtermination de la dilatation thermique linaire Luft- und Raunfahrt - Prfverfahren fr transparente Uerkstoffe zur Verglasung vo
11、n Luftfahrzeugen - Teil 12: Bestimnung der linearen Wrmeausdehnung This European Standard uas approved by CEN on 1997-03-27. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard uit
12、hout any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained or; application to the Central Secretariat or to any CEN member. The European Standards exist in three official versions (English, French, German). A version in any other Language
13、made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgiun, Czech Republic, Demrk, Finland, France, Germany, Greece, Iceland
14、, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Cumnittee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: e de StassartJ6 8-1050 BniEscls 0 1997 CEN - All rights of exploit
15、ation in any form and by any means reserved uorlduide for CE# national Members. Ref. No. EN 2155-12:1997 E - STD-ES1 ES EN 2L55-E2-ENGL Page 2 EN 2155-12:1997 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA) , After inquiries and votes
16、carried out in accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Services of the member countries of AECMA, prior to its presentation to CEN. This European Standard shall be given the status of a national standard, ei
17、ther by publication of an identical text or by endorsement, at the latest by January 1998, and conflicting national standards shall be withdrawn at the latest by January 1998. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound
18、to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. STD-BSI BS-EN 2155-12iENGL 1777 m 3b24bb7 b59443 150 W Page 3 EN 21
19、 55-1 2 1997 1 Scope This standard specifies the method to determine the reversible linear thermal expansion of plastics with exclusion of changes in length due to accidental factors such as changes in moisture content, degree of polymerization and stress release. Since it will not be possible to ex
20、clude all these accidental factors, the method can be expected to give only approximate values. 2 Definition For the purposes of this standard, the following definition applies : Linear thermal expansion is defined as the change in length of a material in relation to unit length for a variation in t
21、emperature of 1 OC. figure 1. An1 3 Apparatus 3.1 Dilatometer A simple fused-quartz tube dilatometer is shown i generally accepted method of measuring thermal expansion may be used which will be accurate to within k 10 YO. The accuracy of the device which measures the expansion shall be such that it
22、 measures the change in length over the temperature interval under consideration within k 2 %. This device shall not exert a stress of more than 50 kPa on this specimen which shall not be distorted or indented. 3.2 Scale or caliper The scale or caliper shall be capable of measuring the test length o
23、f the specimen with an accuracy of I 0,5 Yo. 3.3 Temperature bath The temperature of the specimen shall preferably be controlled by :e use of a liquid bath. The bath shall be arranged in such a way that uniform temperature throughout the specimen is secured. Means shall be provided for stirring the
24、bath and for controlling its temperature within k 0,2 OC of the temperatures used. 4 Specimens 4.1 Preparation Specimens shall be cut or shaped, from sheet. The ends of the specimen shall be cut perpendicular to the axis of the specimen. They shall be protected by means of thin steel plates cemented
25、 to them. 4.2 Dimensions For the apparatus shown in figure 1, specimens can be round or square and shall fit easily into the outer tube without excessive play. The length of the specimen may be 50 mm to 100 mm but its length is governed to some extent by the sensitivity of the dial gauge, the expect
26、ed expansion and the desired accuracy. STD-BSI BS EN 2155-12-ENGL 1997 D Lb24bb7 Ob57Li44 097 D Page 4 EN 2155-12 : 1997 5 Conditioning The specimen shall be conditioned at (23 k 2) OC, (50 f 5) % relative humidity for at least 48 h prior to measurement of the test length of the specimen under these
27、 conditions. 6 Procedure The temperature range over which the coefficient of thermal expansion is to be measured shall be chosen so that no transitional regions are included. The limits of the range shall be agreed between purchaser and manufacturer. 6.1 Low temperature Mount the specimen in the app
28、aratus and maintain the temperature of the bath at the lowest temperature at which measurements are required until the temperature of the specimen reaches the temperature of the bath. The time necessary shall be determined by preliminary measurements of temperature inside a similar specimen. Record
29、the reading of the dial gauge or other device indicating change in length. 6.2 High temperature Repeat the foregoing operations at the highest temperature at which measurements are required. 6.3 Check determination Repeat the operations described in 6.1 and 6.2. If the changes in length caused by he
30、ating and cooling do not agree within 10 % of their average, the cause of this discrepancy shall be investigated and if possible, eliminated (see 6.5). Otherwise the observations shall be reported, see 8.3. 6.4 Constant temperature bath Where the construction of the apparatus permits, it may be more
31、 convenient to alternately use two baths at the required temperatures. Care shall be taken not to disturb the apparatus during exchange. The use of two baths is preferred because it will reduce the time required to bring the specimen to the desired temperature. The test in general shall be conducted
32、 in as short a time as possible to avoid changes in physical properties during long exposure to high and low temperatures. 6.5 Transition temperature The coefficient of thermal expansion of some materials is known to change rather abruptly at a certain temperature. To find this temperature, it is ne
33、cessary to measure the coefficient of thermal expansion in narrow temperature limits, or to observe the rate of expansion during a steady rise in temperature of the specimen. Once such a transition point has been found, a separate coefficient of expansion for a temperature range below and above the
34、transition point shall be determined. STD-BSI BS EN 2155-12-ENGL 1977 D Lb24bb7 Ob57Li45 T23 D Page 5 EN 21 55-1 2 : 1997 7 Expression of results The average coefficient of thermal expansion shall be calculated from the formula : AL Coefficient of linear thermal expansion = - LT where : AL is the av
35、erage of changes in length due to heating or cooling ; L is the test length of specimens immediately after the conditioning stage (AL and L being in the same units) ; T is the temperature difference in OC over which the change in length has been measured. 8 Test report It shall include : 8.1 Tempera
36、tures between which the coefficient of thermal expansion has been computed. 8.2 Average coefficient of linear thermal expansion per OC 8.3 than 10 % in measured values of expansion and contraction Cornpiete description of any unusual behaviour such as, for instance, a difference of more STD-BSI BS E
37、N 2L55-12-ENGL 1797-1 lb24bb Ob5744b 7bT 1 Page 6 EN 2155-12 : 1997 Weld Dial I- Gauge - Adjusting sleeve Thin steel plate cemented or quartz plate fused to inner tube 5 teel bracket cemented to outer tube “-rd II ;i/ I I .-c II II II II h I II I 4 Outer quartz tube - I! 12.5 mm i. O. Inner quartz t
38、ube sliding in outer tube Detail of dial gauge mounting 5 Thin steel plate - Test specimen - cemented to specimen Thin steel plate - cemented to specimen I I l I i B Figure 1 : Quartz-tube dilatometer BS EN 2155-12 : 1997 BSI 389 Chiswick High Road London w4 4AL BSI - British Standards Institution B
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