BS-903-A42-1992 ISO-3384-1991.pdf
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1、BRITISH STANDARD BS 903-A42: 1992 ISO 3384:1991 Physical testing of rubber Part A42: Method for determination of stress relaxation in compression at ambient and at elevated temperatures Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 04:56:24 GMT+00:00 2006, Unc
2、ontrolled Copy, (c) BSI BS 903-A42:1992 This British Standard, having been prepared under the direction of the Plastics and Rubber Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 May 1992 BSI 03-1999 First published January 1983 Second
3、 edition May 1992 The following BSI references relate to the work on this standard: Committee reference PRM/22 Draft for comment 88/40660 DC ISBN 0 580 20819 2 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Plastics and Rubber Standards
4、 Policy Committee (PRM/-) to Technical Committee PRM/22, upon which the following bodies were represented: BP Chemicals Limited British Railways Board British Rubber Manufacturers Association Ltd. GAMBICA (BEAMA Ltd.) Institution of Mechanical Engineers Institution of Water and Environmental Managem
5、ent Malaysian Rubber Producers Research Association Ministry of Defence RAPRA Technology Ltd. SATRA Footwear Technology Centre Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 04:56:24 GMT+00:00 2006, Uncon
6、trolled Copy, (c) BSI BS 903-A42:1992 BSI 03-1999i Contents Page Committees responsibleInside front cover National forewordii Introduction1 1Scope1 2Normative references1 3Definition1 4Principle1 5Apparatus2 6Test piece3 7Duration, temperature and test liquid3 8Procedure4 9Expression of results5 10T
7、est report6 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 04:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 903-A42:1992 ii BSI 03-1999 National foreword This Part of BS 903 has been prepared under the direction of the
8、Plastics and Rubber Standards Policy Committee. It is identical with ISO 3384:1986 Rubber, vulcanized or thermoplastic Determination of stress relaxation in compression at ambient and at elevated temperatures, published by the International Organization for Standardization (ISO). This edition supers
9、edes BS 903-A42:1983 and BS 903-A34 which are withdrawn. The measurement of the stress relaxation of rings is essentially similar to the method using other types of test piece. This Part of BS 903 has therefore been expanded to include the methods previously given in both Parts A42 and A34. Inter-la
10、boratory comparisons showed poor reproducibility of results from stress relaxation tests. To try to overcome this problem, this Part of BS 903 was modified to specify the method used and parts of the apparatus more closely. In particular, the maximum rate of initial compression of the test piece is
11、now specified. The Technical Committee has reviewed the provisions of ISO 37:1977, ISO 468:1982, ISO 1826:1981 and ISO 3601-1:1981, to which normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. Related British Standards for ISO
12、468:1982 and ISO 1826:1981 are BS 1134-1:1988 and BS 903-A19:1986 respectively. There is no British Standard corresponding to ISO 37:1977 but it is envisaged that ISO 37 will correspond to BS 903-A2:1989, after it has been revised. A British Standard does not purport to include all the necessary pro
13、visions 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. Cross-references International standardCorresponding British Standard ISO 471:1983BS 903 Physical testing of
14、rubber Part A35:1985 Temperatures, humidities and times for conditioning and testing of test pieces (Identical) ISO 1817:1985Part A16:1987 Determination of the effect of liquids (Identical) ISO 3383:1985Part A32:1988 General directions for achieving elevated or subnormal temperatures for test purpos
15、es (Identical) ISO 4648:1991Part A38:1991 Determination of dimensions of test pieces and products for test purposes (Identical) ISO 4661-1:1986Part A36:1988 Preparation of samples and test pieces (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and i
16、i, pages 1 to 6, an inside back cover 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. Licensed Copy: London South Bank University, London South Bank University, Fr
17、i Dec 08 04:56:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 3384:1991(E) BSI 03-19991 Introduction When a constant strain is applied to rubber, the force necessary to maintain that strain is not constant but decreases with time; this behaviour is called “stress relaxation”. Conversely, when rub
18、ber is subjected to a constant stress, an increase in the deformation takes place with time; this behaviour is called “creep”. The processes responsible for stress relaxation may be physical or chemical in nature, and under all normal conditions both types of process will occur simultaneously. Howev
19、er, at normal or low temperatures and/or short times, stress relaxation is dominated by physical processes whilst at high temperatures and/or long times chemical processes are dominant. Hence it is neither safe to extrapolate time/stress relaxation curves in order to predict stress relaxation after
20、periods considerably longer than those covered by the test, nor to use tests at higher temperatures as accelerated tests to give information on stress relaxation at lower temperatures. In addition to the need to specify the temperatures and time intervals in a stress relaxation test, it is also nece
21、ssary to specify the initial stress and the previous mechanical history of the test piece since these may also influence the measured stress relaxation, particularly in rubbers containing fillers. 1 Scope This International Standard specifies three methods for determining the decrease in counterforc
22、e exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and maintained thus at a predetermined test temperature. Two forms of test piece are permitted: cylindrical test pieces and rings. Different shapes and sizes of test piece give differe
23、nt results, and comparison of results should be limited to test pieces of similar size and shape. The use of ring test pieces is particularly suitable for the determination of stress relaxation in liquid environments. Testing at temperatures below standard temperature is not specified. The methods h
24、ave been used for low-temperature testing, but their reliability under these conditions is not proven. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editio
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