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1、BS ISO 7743:2008 ICS 83.060 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Rubber, vulcanized or thermoplastic Determination of compression stress- strain properties This British Standard was published under the authority of the Standards Policy and Strategy
2、Committee on 31 July 2008 BSI 2008 ISBN 978 0 580 58455 8 Amendments/corrigenda issued since publication DateComments BS ISO 7743:2008 National foreword This British Standard is the UK implementation of ISO 7743:2008. It supersedes BS ISO 7743:2004 which is withdrawn. The UK participation in its pre
3、paration was entrusted to Technical Committee PRI/22, Physical testing of rubber. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its
4、correct application. Compliance with a British Standard cannot confer immunity from legal obligations. BS ISO 7743:2008 Reference number ISO 7743:2008(E) ISO 2008 INTERNATIONAL STANDARD ISO 7743 Third edition 2008-05-01 Rubber, vulcanized or thermoplastic Determination of compression stress-strain p
5、roperties Caoutchouc vulcanis ou thermoplastique Dtermination des proprits de contrainte/dformation en compression BS ISO 7743:2008 ISO 7743:2008(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall n
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8、member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2008 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
9、or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47
10、 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2008 All rights reserved BS ISO 7743:2008 ISO 7743:2008(E) ISO 2008 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 2 3 Terms and definitions. 2 4 Principle. 2 5 Apparatus an
11、d materials 2 6 Test pieces 3 7 Number of test pieces 4 8 Time-lapse between vulcanization and testing . 4 9 Conditioning 4 10 Temperature of test 4 11 Procedure 4 12 Expression of results . 5 13 Test report . 7 Annex A (informative) Extrapolation of results to non-standard test pieces. 9 Annex B (n
12、ormative) Calibration 12 Bibliography. 14 BS ISO 7743:2008 ISO 7743:2008(E) iv ISO 2008 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is n
13、ormally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part i
14、n the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prep
15、are International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that s
16、ome of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 7743 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This third edition c
17、ancels and replaces the second edition (ISO 7743:2004), Clause 13 and Annex A of which have been technically revised and the references to ISO 471, ISO 3383, ISO 4648 and ISO 4661-1 replaced by ISO 23529. In addition, the tensile-testing machine used is now a class 1 machine rather than the class 0,
18、5 machine previously specified. BS ISO 7743:2008 ISO 7743:2008(E) ISO 2008 All rights reserved v Introduction Knowledge of compression stress-strain properties is important in the design of, for instance, bridge bearings, anti-vibration mountings and O-rings. Measurement of compression stress-strain
19、 behaviour is also used for the quality control of small O-rings and other small products (i.e. under 2 mm thickness) where hardness cannot easily be measured. Compression tests are also used to detect the presence of porosity in products such as pipe sealing rings. BS ISO 7743:2008 BS ISO 7743:2008
20、 INTERNATIONAL STANDARD ISO 7743:2008(E) ISO 2008 All rights reserved 1 Rubber, vulcanized or thermoplastic Determination of compression stress-strain properties WARNING Persons using this International Standard should be familiar with normal laboratory practice. This International Standard does not
21、 purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. CAUTION Certain procedures specified in this International Stan
22、dard may involve the use or generation of substances, or the generation of waste, that could constitute a local environmental hazard. Reference should be made to appropriate documentation on safe handling and disposal after use. 1 Scope This International Standard specifies methods for the determina
23、tion of the compression stress-strain properties of vulcanized or thermoplastic rubber using a standard test piece, a product or a part of a product. Three methods are given: using a standard test piece with the metal plates lubricated (method A); using a standard test piece with the metal plates bo
24、nded to the test piece (method B); using a product or a part of a product with the metal plates lubricated (method C). The three methods do not give the same results. With lubricated test pieces, the results are dependent only on the modulus of the rubber and are independent of the test piece shape,
25、 provided that complete slip conditions are achieved. Effective lubrication is sometimes difficult to achieve, however, and it is prudent to inspect the variance in the test results from replicate test pieces for indications of erratic slip conditions. With bonded test pieces, the results are depend
26、ent on both the modulus of the rubber and the test piece shape. The dependence on test piece shape is strong and consequently the results will be markedly different from those obtained with lubricated test pieces. For products, the result is dependent on the shape, but as tests on products are mainl
27、y comparative this is acceptable. NOTE For well-specified product shapes, such as O-rings, the result may be correlated to the hardness value. Provision is made for the use of test pieces of different size and/or shape from the specified test piece, but extrapolation of the results obtained to other
28、 sizes and shapes may not be possible. Guidance on the effect of size and shape of test piece and of bonding or lubricating is given in Annex A. The methods are not suitable for materials that exhibit high set. The necessary calibration schedule for this type of measurement is included in Annex B. B
29、S ISO 7743:2008 ISO 7743:2008(E) 2 ISO 2008 All rights reserved 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 documen
30、t (including any amendments) applies. ISO 4287, Geometrical Product Specifications (GPS) Surface texture: Profile method Terms, definitions and surface texture parameters ISO 5893, Rubber and plastics test equipment Tensile, flexural and compression types (constant rate of traverse) Specification IS
31、O 18899:2004, Rubber Guide to the calibration of test equipment 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 compression stress stres
32、s applied so as to cause a deformation of the test piece in the direction of the applied stress, expressed as the force divided by the original area of cross-section perpendicular to the direction of application of the force 3.2 compression strain deformation of the test piece in the direction of th
33、e applied stress divided by the original dimension in that direction NOTE The compression strain is commonly expressed as a percentage of the original dimension of the test piece. 3.3 compression modulus secant modulus applied stress calculated on the original area of cross-section divided by the re
34、sultant strain in the direction of application of the stress 3.4 stiffness at 25 % compression force which needs to be applied to a product or a part of a product to compress it by 25 %, expressed in newtons per metre length or in newtons, depending on the shape of the test piece 4 Principle A test
35、piece (lubricated or bonded) is compressed at a constant speed between the compression plates until a pre-determined strain is reached. 5 Apparatus and materials 5.1 Flat metal plates, of uniform thickness and having lateral dimensions greater than or equal to those of test pieces for bonding or at
36、least 20 mm greater than those of test pieces for lubrication. For methods A and C, one surface of each plate shall be highly polished to a surface finish with an arithmetical mean BS ISO 7743:2008 ISO 7743:2008(E) ISO 2008 All rights reserved 3 deviation Ra, determined in accordance with ISO 4287,
37、not greater than 0,4 m. For method B, one surface of each plate shall be suitably prepared for the bonding system to be used. 5.2 Dies and cutters (if required), for preparing test pieces, complying with the relevant requirements of ISO 23529. 5.3 Thickness gauge, complying with the relevant require
38、ments of ISO 23529. 5.4 Compression-testing machine, complying with the requirements of ISO 5893, equipped with means of autographic recording of the force-deformation relationship to an accuracy corresponding to class 1 in respect of force. When testing standard test pieces in methods A and B and l
39、arger test pieces in method C, it shall be possible to determine the displacement with an accuracy of 0,02 mm, including corrections for load cell and device stiffness. When testing products with a height less than that of the standard test piece, it shall be possible to determine the displacement w
40、ith an accuracy of 0,2 % of the height of the test piece, including corrections for load cell and device stiffness. The machine shall be fitted with parallel compression platens at least as large as the metal plates (5.1), and shall be capable of operating at a speed of (10 2) mm/min. For methods A
41、and C, the compression platens can be used directly without the metal plates, provided they have the required surface finish. NOTE Machines with y-time recorders may give erroneous results because of inertia effects; deformation because of compliance in the load cell or machine frame. Machines with
42、x-y recorders are therefore preferred. CAUTION When testing lubricated test pieces, a suitable guard should be provided to avoid damage or injury should the rubber be ejected when strained. 5.5 Lubricant, having no significant effect on the rubber under test, for methods A and C. NOTE For most purpo
43、ses, a silicone or fluorosilicone fluid having a kinematic viscosity of 0,01 m2/s is suitable. 6 Test pieces The standard test piece for both method A and method B is a cylinder of diameter 29 mm 0,5 mm and height 12,5 mm 0,5 mm. Test pieces may be cut or moulded. Cut test pieces shall be prepared i
44、n accordance with ISO 23529. Other test pieces may be used, but extrapolation of the results may not be possible (see Annex A). For method B, test pieces may be directly moulded to the metal plates using a suitable mould and bonding system or adhered to the plates using suitable non-solvent adhesive
45、 systems. It is essential to have test pieces with flat and parallel surfaces. For method C, the test piece is a product, or a part of a product, or multiples thereof. For profiles, a length of 50 mm to 100 mm shall be used as the test piece (or two such lengths together if it is necessary to increa
46、se the force reading). For ring-shaped products with an inner diameter of 50 mm to 100 mm, the whole product shall be used. For small products, two or more products can be tested side by side, parallel to each other, to increase the force reading. BS ISO 7743:2008 ISO 7743:2008(E) 4 ISO 2008 All rig
47、hts reserved 7 Number of test pieces At least three test pieces, or sets of test pieces, shall be tested. 8 Time-lapse between vulcanization and testing Unless otherwise specified for technical reasons, the following requirements shall be observed (see ISO 23529): For all test purposes, the minimum
48、time between vulcanization and testing shall be 16 h. For non-product tests, the maximum time between vulcanization and testing shall be four weeks and for evaluations intended to be comparable the tests, as far as possible, shall be carried out after the same time-interval. For product tests, whene
49、ver possible, the time between vulcanization and testing shall not exceed three months. In other cases, tests shall be made within two months of the date of receipt of the product by the customer. 9 Conditioning Samples and test pieces shall be protected from light as completely as possible during the interval between vulcanization and testing. Samples, after any necessary preparation, shall be conditioned at standard laboratory temperature (see ISO 23529) for at least 3 h before the test pie