1、April 2008DEUTSCHE NORM English price group 10No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 83.100!$NL“1434195www.di
2、n.deDDIN EN ISO 1798Flexible cellular polymeric materials Determination of tensile strength and elongation at break(ISO 1798:2008)English version of DIN EN ISO 1798:2008-04Weich-elastische polymere Schaumstoffe Bestimmung der Zugfestigkeit und der Bruchdehnung (ISO 1798:2008)Englische Fassung DIN EN
3、 ISO 1798:2008-04SupersedesDIN EN ISO 1798:2000-01www.beuth.deDocument comprises 16 pagesDIN EN ISO 1798:2008-04 2 National foreword This standard has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products” in collaboration with Technical Committee CEN/TC 249 “Plastics” (Secretar
4、iat: NBN, Belgium). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NA 062-04-37 AA Prfung weich-elastischer Schaumstoffe. The DIN Standard corresponding to the International Standard referred
5、 to in clause 2 of the EN is as follows: ISO 23529 DIN ISO 23529 Amendments This standard differs from DIN EN ISO 1798:2000-01 as follows: a) The standard has been editorially revised. b) Annex A (informative) “Comparative testing of type 1 and type 1A test pieces” has been added. Previous editions
6、DIN 53571: 1958-08, 1971-06, 1978-02, 1986-01 DIN EN ISO 1798: 2000-01 National Annex NA (informative) Bibliography DIN ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 1798February 2008ICS
7、 83.100 Supersedes EN ISO 1798:1999 English VersionFlexible cellular polymeric materials - Determination of tensilestrength and elongation at break (ISO 1798:2008)Matriaux polymres alvolaires souples - Dterminationde la rsistance la traction et de lallongement larupture (ISO 1798:2008)Weich-elastisc
8、he polymere Schaumstoffe - Bestimmungder Zugfestigkeit und der Bruchdehnung (ISO 1798:2008)This European Standard was approved by CEN on 12 January 2008.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the statu
9、s of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A ve
10、rsion in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Den
11、mark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIO
12、NEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 1798:2008: E2 EN ISO 1798:2008 (E) :DIN EN ISO 1798:2008-04 Contents Page Foreword .3 1 Sc
13、ope .4 2 Normative references .4 3 Terms and definitions 4 4 Apparatus 5 5 Test pieces 5 6 Procedure 7 7 Calculation .7 8 Test report .8 Annex A (informative) Comparative testing of type 1 and type 1A test pieces .9 Bibliography .14 Foreword 3 DIN EN ISO 1798:2008-04 EN ISO 1798:2008 (E) This docume
14、nt (EN ISO 1798:2008) has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products“ in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN. This European Standard shall be given the status of a national standard, either by publicatio
15、n of an identical text or by endorsement, at the latest by August 2008, and conflicting national standards shall be withdrawn at the latest by August 2008. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall n
16、ot be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 1798:1999. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgari
17、a, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of
18、 ISO 1798:2008 has been approved by CEN as a EN ISO 1798:2008 without any modification. WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is t
19、he responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope This International Standard specifies a method for determining the strength and deformation properties of flexible cellular materials when a te
20、st piece is extended at a constant rate until it breaks. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (incl
21、uding any amendments) applies. ISO 1923, Cellular plastics and rubbers Determination of linear dimensions ISO 7500-1:2004, Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system ISO 9
22、513, Metallic materials Calibration of extensometers used in uniaxial testing ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 tensile st
23、rength TS maximum tensile stress applied when stretching a test piece to rupture 3.2 elongation at break Ebpercentage elongation of a test piece at rupture 4 EN ISO 1798:2008 (E) DIN EN ISO 1798:2008-04 4 Apparatus 4.1 Tensile-testing machine, complying with the following requirements: the rate of t
24、ravel of the power-actuated grip shall be 500 mm/min 50 mm/min and shall be uniform at all times; the accuracy of the machine shall conform to class 0,5 or class 1 of ISO 7500-1:2004 for force-measurement over the range of loading employed. For the determination of elongation at break, the machine m
25、ay be equipped with either a mechanical or an optical extensometer. If used, however, the extensometer shall comply with the following requirements which shall be verified in accordance with ISO 9513: initial gauge length accurate to 1 %; gauge length at break accurate to 1,25 mm. When a mechanical
26、contact extensometer is used, care shall be taken that the contact elements do not damage the test piece. In addition, their mass and inertia shall not influence the determination of the maximum tensile strength by more than 1 %. 5 Test pieces 5.1 Direction of sampling If the product shows a predomi
27、nant direction of the cellular structure (orientation of the cells), the test pieces for the tensile test shall be taken in such a way that their longitudinal axes lie at right angles to this predominant direction. If it is not possible, the location of the longitudinal axis with respect to the pred
28、ominant direction shall be stated in the test report. 5.2 Shape and dimensions The test pieces shall be rectangular in cross-section, with or without skin, and without visible defects. The test pieces shall be cut out with one of the two types of test piece cutter shown in Figure 1 and shall be 10 m
29、m to 15 mm thick. 5.3 Number of test pieces Unless agreed otherwise between the interested parties, sufficient test pieces shall be tested to provide five breaks within the gauge length. 5 EN ISO 1798:2008 (E) DIN EN ISO 1798:2008-04 Dimensions in millimetres a) Type 1 b) Type 1A Figure 1 Test-piece
30、 cutters 5.4 Conditioning 5.4.1 The test pieces or the material from which the test pieces are to be cut shall be prepared and conditioned in accordance with ISO 23529, unless otherwise specified. 5.4.2 Materials shall not be tested less than 72 h after manufacture, unless at either 16 h or 48 h aft
31、er manufacture it can be demonstrated that the mean results do not differ by more than 10 % from those obtained after 72 h. Testing is permitted at either 16 h or 48 h if, at the specified time, the above criterion has been satisfied. Prior to the test, the test pieces or the material from which the
32、 test pieces are to be cut shall be conditioned for at least 16 h in one of the following atmospheres: 23 C 2 C, (50 5) % relative humidity; 27 C 2 C, (65 5) % relative humidity. This period can form the latter part of the period following manufacture. 5.4.3 In the case of quality-control tests, tes
33、t pieces can be taken a shorter time (down to a minimum of 12 h) after manufacture and testing carried out after conditioning for a shorter period (down to a minimum of 6 h) in one of the atmospheres specified above. 6 EN ISO 1798:2008 (E) DIN EN ISO 1798:2008-04 6 Procedure 6.1 After conditioning a
34、s specified in 5.4, measure the thickness of the material at five evenly distributed points in the area from which the test pieces are to be cut. These measurements shall be made in accordance with ISO 1923 and shall not vary from each other by more than 2 %. If desired, thickness measurements can b
35、e performed on cut test pieces, but test pieces whose thickness falls outside these limits shall be rejected. 6.2 Mark the gauge length on each test piece with two reference lines, using a marker with two parallel marking edges. Measure the distance between the inside edges of the lines to an accura
36、cy of 1 % (these lines shall be at least 25 mm and not more than 50 mm apart for type 1 test pieces and not more than 40 mm apart for type 1A test pieces). 6.3 Set the load-indicating device to zero and place a test piece in the grips of the tensile-testing machine (4.1), taking care to mount the te
37、st piece symmetrically so that the tension will be distributed uniformly over its cross-section. A preload stress of up to 0,1 kPa or a preload extension of up to 0,5 % may be applied. When using an extensometer, zero it on completion of the preload. Start the machine at a jaw-separation rate of 500
38、 mm/min 50 mm/min and record the maximum force (measured to 1 %) and the distance between the inside edges of the two reference lines (measured to 1,25 mm) immediately prior to break of the test piece. Reject test pieces which break outside the gauge length, and continue testing until five satisfact
39、ory results are obtained. Sufficient material will have to be available to ensure that retesting can be carried out. 6.4 Carry out the test at the same temperature and humidity as that used for conditioning the test material. NOTE In the case of the type 1 cutter, the probability of test pieces bein
40、g rejected can be minimized by selecting a gauge length close to the maximum permitted value of 50 mm. 7 Calculation 7.1 Tensile strength Calculate the average thickness of each test piece. Calculate the average initial cross-sectional area of each test piece on the basis of the average thickness an
41、d the width of the central section of the test piece cutter (13 mm for type 1 and 10 mm for type 1A). The tensile strength (TS) of each test piece, expressed in kilopascals, is given by the equation 3TS 10FA=where F is the maximum force, in newtons; A is the average initial cross-sectional area, in
42、square millimetres. 7.2 Elongation at break The elongation at break, Eb, expressed as a percentage of the original gauge length, is given by the equation 0b0100LLEL=where L is the gauge length at break, in millimetres; L0is the initial gauge length, in millimetres. 7 EN ISO 1798:2008 (E) DIN EN ISO
43、1798:2008-04 8 Test report The test report shall include the following information: a) a reference to this International Standard; b) the nature of the cellular material; c) the type of test piece used; d) details of test piece conditioning; e) the location in the product from which the test pieces
44、were taken, and the predominant direction of the cellular structure, if any; f) the location and number of surfaces with skin, if any; g) the test piece thickness; h) the median value of the tensile strength, in kilopascals; i) the median value of the elongation at break, in percent; j) any deviatio
45、ns from this International Standard. 8 EN ISO 1798:2008 (E) DIN EN ISO 1798:2008-04 Annex A (informative) Comparative testing of type 1 and type 1A test pieces A.1 General This annex gives a comparison of test results obtained with the new type 1A test piece and the old type 1 test piece. A.2 Compar
46、ative testing Two types of test piece (type 1 and type 1A) were used. Two types of flexible polyurethane foam were used: sample A: 22 kg/m3general-purpose type; sample B: 32 kg/m3high-hardness type. Both samples were of the polyether type. In order to ensure the accuracy of the test, the test pieces
47、 were cut from the same test material with the same test piece cutter. Fifteen test pieces were prepared for each test. Testing was carried out at seven laboratories in Japan on two days in different weeks. The test method and test piece conditioning were as specified in ISO 1798:1997. A.3 The test
48、method and the rate of breaking outside the gauge length The type 1 test pieces were marked with gauge lengths of 25 mm, 40 mm, 50 mm and 55 mm. Although ISO 1798 specifies a gauge length of 25 mm to 50 mm, a gauge length of 55 mm was included since there was room for it within the narrow portion of
49、 the test piece. The type 1A test piece was marked only at 40 mm since the gauge length of the test piece is specified as 40 mm. The frequency of breaking outside the gauge length was calculated as a percentage from the following equation: 100OkT=where k is the frequency of breaking outside the gauge length, in percent; O is the number of test pieces that broke outside the gauge length during the two days; T is the total number of test pieces tested during the two days. 9 EN ISO 1798:2008 (E) D
