1、BRITISH STANDARD AEROSPACE SERIES BS EN 2747:1998 Glass fibre reinforced plastics Tensile test The European Standard EN2747:1998 has the status of a British Standard ICS 49.025.40BSEN 2747:1998 This British Standard, having been prepared under the directionof the Engineering SectorCommittee, was pub
2、lishedunder the authority ofthe Standards Committee andcomes into effect on 15November1998 BSI 05-1999 ISBN 0 580 30716 6 National foreword This British Standard is the English language version of EN2747:1998. The UK participation in its preparation was entrusted to Technical Committee ACE/64, Aeros
3、pace structural reinforced plastics, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and
4、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 S
5、tandards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsib
6、le 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, theEN title page, pages2 to11 and a back cover. This standard has been update
7、d (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSEN2747:1998 BSI 05-1999 i Contents Page National foreword Inside front cover Foreword 2 Text of EN2747
8、 3ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 2747 August 1998 ICS 49.025.40 Descriptors: Aircraft industry, reinforced plastics, glass reinforced plastics, tests, tension tests English version Aerospace series Glass fibre reinforced plastics Tensiletest Srie arospatiale Plastiques
9、renforcs au verre textile Essai de traction Luft- und Raumfahrt Glasfaserverstrkte Kunststoffe Zugversuch This European Standard was approved by CEN on15 May1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standar
10、d 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. This European Standard exists in three official versions (English, French, Ge
11、rman). 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, CzechRepublic, Denmark, F
12、inland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050
13、 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN2747:1998 EEN2747:1998 BSI 05-1999 2 Foreword This European Standard has been prepared by the European Association of Aerospace Manufacturers (AECMA). After inquiries an
14、d 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 sta
15、ndard, either by publication of an identical text or by endorsement, at the latest by February1999, and conflicting national standards shall be withdrawn at the latest by February1999. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries
16、are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3
17、 3 Definitions 3 4 Principle 4 5 Apparatus 4 6 Specimens 4 7 Procedure 7 8 Expression of results 8 9 Designation 10 10 Test report 10 Figure 1 Specimen type1 4 Figure 2 Specimen type2 5 Figure 3 Specimen type3 6 Figure 4 Specimen type4 6 Figure 5 Tensile stress/strain diagramm 9 Figure 6 Method for
18、preparing specimens with bonded tabs 11 Table 1 Types of specimens 5EN2747:1998 BSI 05-1999 3 1 Scope This standard specifies a method for the determination of tensile properties of glass fibre reinforced plastics for aerospace applications. 2 Normative references This European Standard incorporates
19、 by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Sta
20、ndard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 2374, Aerospace series Glass fibre reinforced mouldings and sandwich composites Production of test panels. EN 2489, Aerospace series Fibre reinforced plas
21、tics Determination of the action of liquid chemicals. EN 2743, Aerospace series Reinforced plastics Standard atmospheres for conditioning and testing 1) . EN 2823, Aerospace series Fibre reinforced plastics Test method for the determination of the effect of exposure to humid atmosphere on physical a
22、nd mechanical characteristics 1) . 3 Definitions For the purpose of this standard the following definitions apply: 3.1 tensile stress tensile load experienced by the specimen at any moment during the test, per initial unit cross sectional area within the free length 3.2 ultimate tensile strength ten
23、sile stress at the moment failure occurs 3.3 strains change in the distance between reference points in the specimen free length, produced by a tensile load and expressed with respect to the initial distance between these points 3.4 percentage strain to failure increase in the distance between refer
24、ence points in the specimen free length, produced by a tensile load and expressed as a percentage of the initial distance between these points and measured at the moment of failure 3.5 Modulus of elasticity Quotient of the tensile stress and corresponding strain within the linear area. NOTEIt is the
25、 slope of the stress/strain diagram obtained during the tensile test. If the limit of proportionality is exceeded or if them is no linear area, it is necessary to define: 3.5.1 tangent modulus slope of the tangent at the origin of the stress/strain diagram 3.5.2 secant modulus at x% slope of the str
26、aight line going through the origin of the stress/strain diagram and the point in this diagram which corresponds to a strain of x% 1) Published as AECMA Prestandard at the date of publication of this standardEN 2747:1998 4 BSI 05-1999 4 Principle The method consists of the measurement of the longitu
27、dinal strain in the material, in relation to the load applied, during a tensile test carried out at a constant speed until failure occurs. This method enables the following tensile properties to be determined: ultimate tensile strength; modulus of elasticity; percentage strain to failure. 5 Apparatu
28、s 5.1 Test machine Constant speed tensile machine with: a) A fixed part with a suitable grip and a mobile part with a second grip. The grips shall be designed such that the axis of the specimen is aligned at all times with the direction of the applied load. This can be achieved, for example, by usin
29、g centring pins within the grips. b) A load measuring system of negligible inertia accurate to1% in the load range used. The fixed and mobile parts shall be constructed such that during the test the total longitudinal deformation of these parts does not exceed1% of the specimen free length. This req
30、uirement applies for the whole of the load range used. 5.2 Extensometer It shall enable determination of the distance between two reference marks situated on the free length of the specimen at any time during the test. The extensometer used shall not damage the specimen nor cause failures at the att
31、achment points. The extensometer of negligible inertia with regard to the test speed, shall give the strain to 1% of the measured value. The gauge lengths recommended are given in Table 1. However, shorter distances may be used, as long as the above requirements are met. 5.3 Micrometer with6mm diame
32、ter flat faces and accurate to 0,01mm. 6 Specimens 6.1 Dimensions The types of specimens are defined in Table 1 and Figure 1 to Figure 4. Figure 1 Specimen type1EN2747:1998 BSI 05-1999 5 Table 1 Types of specimens Dimensions in millimetres Thermoplastics Thermosets Unidirectional thermosets Recommen
33、ded specimen types Type1 Type2 Type3 Type4 F Minimum total length 150 250 250 164 W Width of ends 20 0,5 h thickness of specimen Semi-finished products 2 to10 2 to10 2 to10 Test panels according to EN2374 2 to3,5 2 to3,5 2 to3,5 1 0,2 to 3 0,2 B Free length 60 0,5 b Width of free length 10 0,5 25 0,
34、5 25 0,5 10 0,5 L o Gauge length 50 50 or 100 50 or 100 25 E Distance between grips 115 5 170 5 170 5 50 2 D Distance between tabs 150 5 64 1,5 T Minimum length of tabs 50 50 P Diameter of centring holes (drilling of holes optional) e Thickness of tabs 2 0,2 0,5 0,1 R Radius $ 60 Figure 2 Specimen t
35、ype2 3 +0,25 0,05 3 +0,25 0,05 3 +0,25 0,05EN 2747:1998 6 BSI 05-1999 Figure 3 Specimen type3 Figure 4 Specimen type4EN2747:1998 BSI 05-1999 7 6.2 Specimens preparation For thermosets, the specimens shall be cut from panels made according to EN2374. For thermoplastics use preferably compression moul
36、ded panels to obtain the specimens. The results from injection moulded specimens are mainly influenced by the orientation of the fibre. This manufacturing method may be used, when other methods for manufacturing specimens are not possible. If the specimens are to be taken from finished components, t
37、hey shall be taken preferably from flat areas or those with minimum curvature. Avoid reducing thicknesses through a machining operation. If the surfaces of the specimens have been machined, the results obtained will not be comparable to those obtained on non-machined specimens. The lay up of the lam
38、inate and subsequent machining shall be carried out in such a way that the orientation of the fibre in the test direction is achieved to within 1. 6.3 Preparation and application of tabs (recommendation) Cut out, from the material to be tested, a sheet with the length of the specimens and width to s
39、uit the required number. To form the tabs, cut out, preferably from a material with a modulus of elasticity that is lower than that of the material being tested, rectangular strip to conform to the requirements of Table 1 and Figure 6. Fix the strips as follows (see Figure 6): a) Abrade all the surf
40、aces to be bonded with fine abrasive paper. b) Carefully clean these with an appropriate solvent. c) Use an adhesive (for example an epoxy adhesive) of flexible type, with an elongation at failure greater than that of the material tested. d) Position the strips so that they are perfectly aligned at
41、each end, parallel to one another and perpendicular to the longitudinal direction of the specimens. e) Maintain under pressure for a sufficient period of time. This assembly (panel and tabs) constitutes a blank ready for cutting into specimens. 6.4 Machining Avoid process conditions that cause the s
42、pecimen to overheat. It is recommended that a cooling fluid be used. In this case make sure the specimen is wiped dry immediately after machining. Check that the edges of the specimen are free of defects. 6.4.1 Type1 specimens It is desirable to machine specimens with an abrading wheel or mill, usin
43、g a template. 6.4.2 Type2,3 and4 specimens Preferably use diamond or silicon carbide saws. 6.5 Number Minimum of five for each test direction. 7 Procedure 7.1 Conditioning EN2743 for tests in the initial state; EN2489 for tests after immersion; EN2823 for tests after exposure to humid atmosphere. 7.
44、2 Test atmosphere Unless otherwise specified, carry out the tests at(23 2)C and(50 5)% relative humidity. 7.3 Measurement of the dimensions of the test specimens Make three of width to 0,1mm and of thickness to 0,02mm, on the specimen centreline: one at the centre, the others at distance(0,5L o 5)mm
45、 from the centre.EN 2747:1998 8 BSI 05-1999 7.4 Recording and calculation of the widths and thicknesses Record the minimum and maximum values of width and thickness and make sure that they are within the tolerances given in Table 1. Calculate the arithmetical mean of the widths b and thicknesses h.
46、7.5 Test Place the specimen in the grips, taking care to align its axis with that of the test machine. When the centring pins are used, good alignment is obtained by light tension on the specimen before clamping the grips together. Clamp uniformly and strongly to avoid any slipping of the specimen.
47、Check and, if required, calibrate the extensometer. Fix it at the centre of the specimen. NOTEIf a tensile load has been applied during clamping in the grips, reduce this to zero before measuring strain. Apply a test speed of(2 0,2)mm/min and record the load as a function of elongation (Z = L L o ).
48、 8 Expression of results 8.1 Ultimate tensile strength where: Record the result to three significant figures. 8.2 Percentage strain to failure where: Record the result to two significant figures. 8.3 Tangent modulus where: B is the ultimate tensile strength, in megapascals, F is the maximum load, in
49、 newtons, b is the initial average width of the specimen, in millimetres, h is the initial average thickness of the specimen, in millimetres. a is the strain to failure, in per cent; Z r is the increase in the distance between reference points measured at failure and expressed in millimetres; L o is the gauge length, in millimetres. E t is the tangent modulus, in megapascals; %F 1 is the change in load, in newtons (see F
