1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1875-3:1998 The Eur
2、opean Standard EN 1875-3:1997 has the status of a British Standard ICS 59.080.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Rubber- or plastics-coated fabrics Determination of tear strength Part 3: Trapezoidal methodThis British Standard, having been prepared under the di
3、rection of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 March 1998 BSI 1998 ISBN 0 580 29274 6 BS EN 1875-3:1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standa
4、rd is the English language version of EN 1875-3:1997. It is an additional method to methods 7A to 7C for the determination of tear strength given in BS 3424-5:1982. NOTE The European Standard refers to a tensile testing machine of constant rate of extension.I n the UK the type of machine described i
5、s normally referred to as being of constant rate of traverse. The UK participation in its preparation was entrusted to Technical Committee TCI/78, Coated fabrics, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee any enquiries on the
6、 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 Standar
7、ds 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. A British Standard does
8、 not purport to include all the necessary provisions of a contact. 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
9、 front cover, the EN title page, pages 2 to 6, an inside back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any for
10、m and by any means reserved worldwide for CEN national Members. Ref No. EN 1875-3:1997 E EUROPEAN STANDARD EN 1875-3 NORME EUROPE ENNE EUROPA ISCHE NORM November 1997 ICS 59.080.40 Descriptors: Textiles, coated fabrics, fabrics coated with rubber, fabrics coated with plastics, tests, tear tests, tea
11、r strength, test specimens English version Rubber- or plastics-coated fabrics Determination of tear strength Part 3 : Trapezoidal method Supports textiles reve tus de caoutchouc ou de plastique De termination de la re sistance au de chirement Partie 3 : Me thode sur e prouvettes trape zo dales Mit K
12、autschuk oder Kunststoff beschichtete Textilien Bestimmung der Weiterreifestigkeit Teil 3 : Verfahren mit trapezfo rmigen Probeko rpern This European Standard was approved by CEN on 16 October 1997. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditi
13、ons 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. This European Standard exists in three of
14、ficial 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
15、, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1875-3:1997 BSI 1998 Foreword This European Standard has been prepared by Technical Committee CEN/TC 248,
16、Textiles and textile products, the Secretariat of which is held by BSI. 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 May 1998, and conflicting national standards shall be withdrawn at the lates
17、t by May 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, Netherlan
18、ds, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. This European Standard forms part of a European Standard on tear resistance of coated fabrics as follows pr EN ISO 4674-1 Rubber- or plastics-coated fabrics Determination of tear resistance Part 1: Three tongue and trousers tes
19、t pieces pr EN ISO 4674-2 Rubber- or plastics-coated fabrics Determination of tear resistance Part 2: Ballistic method prEN 1875-3 Rubber- or plastics-coated fabrics Determination of tear resistance Part 3: Trapezoidal method The first Part describes two methods using a tensile testing machine at a
20、constant rate of elongation. The second Part describes a dynamic method using the kinetic energy of a falling pendulum. For these two Parts, tearing propagates in a direction parallel to the applied force. The third Part uses a trapezoidal test piece, where tearing propagates in a direction perpendi
21、cular to the applied force. NOTE Trapezoidal method should logically be classified with the constant speed methods but is generally considered apart owing to the direction of propagation. Attention is drawn to the fact that the results of the different methods cannot be compared, owing to the differ
22、ences of principle. Other methods are under consideration as possible further Parts, for example the wounded burst test. Contents Page Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Principle 3 5 Apparatus 3 6 Test specimens 3 7 Procedure 4 8 Expression of results 5 9
23、 Test report 5 Annex A (informative) Tear strength Trapezoidal method Note on the choice of test sample dimensions 5Page 3 EN 1875-3:1997 BSI 1998 Introduction Tearing is amongst the more usual ways of destruction for many thin materials. Knowledge of the resistance of these materials to this type o
24、f behaviour is therefore very important. In practice, tearing can result from very different circumstances: hence the large number of test methods that have been developed in order to predict the behaviour of the materials in various situations. NOTE Persons using this standard should be familiar wi
25、th normal laboratory practice. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations p
26、rior to use. 1 Scope This standard specifies test conditions and the procedure to be followed for determining the tear strength of a trapezoidal specimen of a rubber- or plastics-coated fabric, using a tensile testing machine. This test may be carried out: either on test specimens conditioned in ref
27、erence atmospheres; or on test specimens which have been subjected to any necessary treatment for the application considered, for example dipping. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative references
28、 are cited at the appropriate places in the text and the publications are listed hereunder. For dated references, further amendments or revisions apply to the present European Standard only if they have been incorporated by amendment or revision. For undated references the most recent edition of the
29、 cited publication apply. EN ISO 2231 Rubber- or plastics-coated fabrics Standard atmospheres for conditioning and testing EN 22286 Rubber- or plastics-coated fabrics Determination of roll characteristics ISO 7500-1 Metallic materials Verification of static uniaxal testing machines Part 1 Tensile te
30、sting machines 3 Definitions For the purposes of this standard the following definitions apply: 3.1 tearing tearing action 3.2 tear the result of tearing 3.3 tear strength of coated fabrics the property of a coated fabric to resist a force tending to separate the threads or fibres making up the coat
31、ed fabric before tearing, by breaking some of these threads or fibres 4 Principle The threads or fibres forming a coated fabric are subjected successively to a force designed to break them. The values of the breaking forces are recorded as the mobile jaw moves. 5 Apparatus 5.1 Constant rate of exten
32、sion (CRE) tensile testing machine, fitted with parallel jaws, having the following general characteristics. The tensile testing machine shall be provided with means for reading and recording both the force applied to the test specimen in stretching it to rupture and the corresponding extension of t
33、he test specimen. It will be provided with a strength indicator having several scales in order to ensure that the rupture of each test specimen shall be obtained with a strength of 15 % to 85 % of the maximum of the scale used. Under conditions of use, the accuracy of the apparatus should be of clas
34、s 1 in accordance with ISO 7500-1. The error of the indicated or recorded maximum force at any point in the range in which the machine is used shall not exceed 1 %, and the error of the indicated or recorded jaw separation shall not exceed 1 mm. After the first 2 s of the test, the rate of increase
35、in the distance between the clamps shall be uniform to within 5 %. 6 Test specimens 6.1 Atmosphere for conditioning and testing Samples shall be conditioned in one of the atmospheres as specified in EN ISO 2231. The test shall be carried out in the same atmosphere. These requirements need not be app
36、lied to samples that have been subjected to some treatments such as dipping. 6.2 Sampling Specimens shall be taken from the sample at a position with no visible or functional flaw and shall be located within the useful width of the part as defined in EN 22286. 6.3 Dimensions Each test specimen shall
37、 have the following dimensions: (75 1) mm3 (150 1) mm (see Figure 1) 6.4 Number For each measurement series, take five test specimens in the longitudinal direction and five test specimens in the transverse direction.Page 4 EN 1875-3:1997 BSI 1998 1 Mark for the attachments 2 Incision 15 to begin the
38、 tearing 3 Moving Figure 1 Mark for the positioning of attachments 6.5 Preparation For the measurements of the longitudinal tearing force (for a woven fabric, breakage of the warp threads), the length of the test specimen shall be parallel to the edge of the coated part. For the measurements of the
39、transverse tearing force (for a woven fabric, breakage of the weft threads), the length of the test specimen shall be perpendicular to the edge of the coated part. Mark the position of the attachments on the test specimen, then make the initiating incision, as shown in Figure 1. 7 Procedure Place a
40、test specimen in the attachments such that the lower edge of the upper attachment and the upper edge of the lower attachment coincide with the marks on the test specimen. The specimen is then stretched on the side of the incision and forms a fold on the other side. Start the tensile testing machine
41、at a rate of (100 10) mm/min. Tearing will propagate in a direction almost perpendicular to the length of the test specimen. Continue the test until rupture, recording the load-deformation curve. This curve will normally contain peaks. Tear the specimen completely. Repeat this operation for each tes
42、t specimen.Page 5 EN 1875-3:1997 BSI 1998 Figure A.1 8 Expression of results For each test specimen, the trace is divided in four equal parts. The average of the five highest peaks of the two central parts is taken as the tear strength. For each direction, longitudinal and transverse, the result is
43、the average of the five test results, rounded to three digits. When an anomaly occurs (direction of tearing, recording curve not containing any peaks, coated fabric support separation, etc.), this anomaly shall be noted on the test report and results interpreted with caution. 9 Test report The test
44、report shall mention: a) the test date; b) a reference to this standard; c) conditioning and test atmospheres used; d) the material reference and thickness; e) values of each specimen; f) average values in the longitudinal and transverse tearing forces; g) if applicable, any special specimen treatme
45、nt; h) any anomalies; and i) operational details not described in this European Standard and incidents which may have an influence on the results. Annex A (informative) Tear strength Trapezoidal method Note on the choice of test sample dimensions As mentioned in this European Standard, tear strength
46、 is the property of a coated fabric to resist a force tending to separate its constituent threads, before it breaks. In tearing, threads should theoretically or ideally be stressed one after the other, whereas the threads are all fully stressed at the time in the measurement of tensile strength. A g
47、ood method for measurement of the tear strength should respect this principle. With the trapezoidal method, at the start of the test, the material should only be stretched at the position of the notch (short side of the trapezium), the rest of the sample should remain slack in order to maintain the
48、above principle. This configuration should be maintained throughout the period of test. This is only possible if the test sample width (L)i sa s large as practically possible, and, for a given width, with the smallest possible angle (a) (see Figure A.1). The present method satisfies this criterion c
49、orrectly. In order to confirm this statement, a comparative study was made of two standardized methods A and B. Method A has an angle (a)o f7 58 , whereas method B has an angle (a)o f6 28 . The significantly higher values for method A prove that more threads are stressed at the same time, thus approaching a rupture strength measurement: the low values obtained by method B are more representative of tearing. The test specimen chosen for this European Standard is identical to that o
