BRITISH STANDARD AEROSPACE SERIES BS EN 2155 12 1997 Test methods for transparent materials for aircraft glazing — Part 12 Determination of linear thermal expansion The European Standard EN 2155 12 19[.]
BRITISH STANDARD AEROSPACE SERIES Test methods for transparent materials for aircraft glazing — Part 12: Determination of linear thermal expansion The European Standard EN 2155-12:1997 has the status of a British Standard ICS 49.025.99; 49.045 BS EN 2155-12:1997 BS EN 2155-12:1997 National foreword This British Standard is the English language version of EN 2155-12:1997 The UK participation in its preparation was entrusted to Technical Committee ACE/62, 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 proposals for change, and keep the UK interests informed; — monitor 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 document 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 European Standards may appear in clause in the form of a three-digit number e.g -001 where the BSI and CEN systems would use the form -1 It can be assumed that, wherever referenced, the three-digit and single digit forms can be used interchangeably For the purposes of part-marking of components produced in accordance with this standard, the three-digit form should be used A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application 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, pages i and ii, the EN title page, pages to and a back cover This standard has been updated (see copyright date) and may have had amendments incorporated This will be indicated in the amendment table on the inside front 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 15 November 1997 © BSI 04-2000 ISBN 580 28134 Amendments issued since publication Amd No Date Comments BS EN 2155-12:1997 Contents National foreword Foreword Text of EN 2155-12 © BSI 04-2000 Page Inside front cover i ii blank EN 2155-12 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM July 1997 ICS 49.025.40 Descriptors: Aircraft industry, glazing, materials, transparency, plastics, tests, determination, thermal properties, thermal expansion English version Aerospace series — Test methods for transparent materials for aircraft glazing — Part 12: Determination of linear thermal expansion Série aérospatiale — Méthodes d’essais pour matériaux transparents pour vitrages aéronautiques — Partie 12: Détermination de la dilatation thermique linéaire Luft- und Raumfahrt — Prüfverfahren für transparente Werkstoffe zur Verglasung von Luftfahrzeugen — Teil 12: Bestimmung der linearen Wärmeausdehnung This European Standard was approved by CEN on 1997-03-27 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on 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 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, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1997 CEN — All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 2155-12:1997 E EN 2155-12:1997 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA) After inquiries and votes 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, either 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 CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound 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 Contents Foreword Scope Definition Apparatus Specimens Conditioning Procedure Expression of results Test report Figure — Quartz-tube dilatometer Page 3 3 3 4 © BSI 04-2000 EN 2155-12:1997 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 exclude all these accidental factors, the method can be expected to give only approximate values 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 temperature of °C Apparatus 3.1 Dilatometer A simple fused-quartz tube dilatometer is shown in Figure Any generally accepted method of measuring thermal expansion may be used which will be accurate to within ± 10 % The accuracy of the device which measures the expansion shall be such that it measures the change in length over the temperature interval under consideration within ± % 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 of the specimen with an accuracy of ± 0,5 % 3.3 Temperature bath The temperature of the specimen shall preferably be controlled by the 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 bath and for controlling its temperature within ± 0,2 °C of the temperatures used 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 to them © BSI 04-2000 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 expected expansion and the desired accuracy Conditioning The specimen shall be conditioned at (23 ± 2) °C, (50 ± 5) % relative humidity for at least 48 h prior to measurement of the test length of the specimen under these conditions 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 apparatus 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 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 heating and cooling 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 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 in as short a time as possible to avoid changes in physical properties during long exposure to high and low temperatures EN 2155-12:1997 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 necessary 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 transition point shall be determined Test report It shall include: 8.1 Temperatures between which the coefficient of thermal expansion has been computed 8.2 Average coefficient of linear thermal expansion per °C 8.3 Complete description of any unusual behaviour such as, for instance, a difference of more than 10 % in measured values of expansion and contraction Expression of results The average coefficient of thermal expansion shall be calculated from the formula: Coefficient of linear thermal expansion = % L LT where: %L is the average of changes in length due to heating or cooling; L is the test length of specimens immediately after the conditioning stage (%L and L being in the same units); T is the temperature difference in °C over which the change in length has been measured © BSI 04-2000 EN 2155-12:1997 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