1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationRubber, vulcanized Determination of creep in compression or shearBS ISO 8013:2012National forewordThis British Standard is the UK implementation of ISO 8013:2012. It supersedes B
2、S ISO 8013:2006 which is withdrawn.The UK participation in its preparation was entrusted to Technical CommitteePRI/22, Physical testing of rubber.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the nece
3、ssary provisions of acontract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 69689 3ICS 83.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was pub
4、lished under the authority of the StandardsPolicy and Strategy Committee on 31 December 2012.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS ISO 8013:2012 ISO 2012Rubber, vulcanized Determination of creep in compression or shearCaoutchouc vulcanis Dtermination du flu
5、age en compression ou en cisaillementINTERNATIONAL STANDARDISO8013Third edition2012-10-01Reference numberISO 8013:2012(E)BS ISO 8013:2012ISO 8013:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication ma
6、y be reproduced or utilized in any form 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 officeCase postale 56 CH-1211 Geneva 20Tel. +
7、41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 8013:2012ISO 8013:2012(E) ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope 12 Normative references . 13 Terms and definitions . 14 Apparatus 24.1 Thickness-measuring
8、device . 24.2 Compression device for measurement in compression . 24.3 Shear device for measurements in shear . 24.4 Temperature-controlled chamber 34.5 Timer . 35 Calibration . 76 Test piece . 76.1 Test piece for measurements in compression 76.2 Test piece for measurements in shear 76.3 Number . 77
9、 Time-lapse between vulcanization and testing . 88 Mechanical conditioning . 99 Test temperature 910 Procedure 910.1 Testing 910.2 Duration of test 1011 Calculation of results .1011.1 Creep increment 1011.2 Creep index . 1111.3 Compliance increment . 1112 Expression of results .1213 Test report .12A
10、nnex A (informative) Values of forces required for rubbers of different hardnesses 14Annex B (normative) Calibration schedule15Bibliography .18BS ISO 8013:2012ISO 8013:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
11、member bodies). The work of preparing International Standards is normally 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, govern
12、mental and non-governmental, in liaison with ISO, also take part in 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 Dir
13、ectives, Part 2.The main task of technical committees is to prepare 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 bod
14、ies casting a vote.Attention is drawn to the possibility that some 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 8013 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
15、 Subcommittee SC 2, Testing and analysis.This third edition cancels and replaces the second edition (ISO 8013:2006), which has been revised to include a calibration schedule for the apparatus used (see Annex B). In addition, the maximum thickness of test pieces for measurement in shear (see 6.2) has
16、 been increased from 12 mm to 13 mm.iv ISO 2012 All rights reservedBS ISO 8013:2012ISO 8013:2012(E)IntroductionWhen a constant stress is applied to rubber, the deformation is not constant but increases gradually with time; this behaviour is called “creep”. Conversely, when rubber is subjected to a c
17、onstant strain, a decrease in the stress in the material takes place; this behaviour is called “stress relaxation”.The creep test is of particular interest where vulcanized rubbers are used to support a constant load, such as in bearings or mountings.The processes responsible for creep can be physic
18、al or chemical in nature, and under all normal conditions both processes will occur simultaneously. However, at normal or low temperatures and/or short times, creep is dominated by physical processes, whilst at high temperatures and/or long times, chemical processes are dominant. In general, physica
19、l creep is found to be directly proportional to logarithmic time, and chemical creep to linear time; but great care has to be taken in extrapolating time/creep curves in order to predict creep after periods considerably longer than those covered by the test, and in using tests at higher temperatures
20、 as accelerated tests to give information on creep at lower temperatures.In addition to the need to specify the temperature intervals and time intervals in a creep test, it is also necessary to specify the initial strain and the previous mechanical history of the test piece, since these might also i
21、nfluence the measured creep, particularly in rubbers containing filler. ISO 2012 All rights reserved vBS ISO 8013:2012Rubber, vulcanized Determination of creep in compression or shearWARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard d
22、oes not 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.1 ScopeThis International Standard specifies a method for
23、 the determination of creep in vulcanized rubber continuously subjected to compressive or to shear forces. The standard cannot be used for intermittent deformation of rubber.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated ref
24、erences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 1827, Rubber, vulcanized or thermoplastic Determination of shear modulus and adhesion to rigid plates Q uadruple shear methodsISO 4664-1, Rubber, vulc
25、anized or thermoplastic Determination of dynamic properties P art 1: General guidanceISO 18899:2004, Rubber Guide to the calibration of test equipmentISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods3 Terms and definitionsFor the purposes of th
26、is document, the following terms and definitions apply.3.1creep incrementincrease in strain which occurs in a specified time interval under constant force and at constant temperatureNOTE It is expressed as the ratio of the increase in deformation over the time interval to the initial, unstrained thi
27、ckness.3.2creep indexrelative increase in strain which occurs in a specified time interval under constant force and at constant temperatureNOTE It is expressed as the ratio of the increase in the strain over the time interval to the strain at the beginning of the interval.3.3compliance incrementrati
28、o of the increase in strain which occurs in a specified time interval under constant force and at constant temperature to the constant stress appliedINTERNATIONAL STANDARD ISO 8013:2012(E) ISO 2012 All rights reserved 1BS ISO 8013:2012ISO 8013:2012(E)4 Apparatus4.1 Thickness-measuring deviceThicknes
29、s measurements shall be made using a device complying with either ISO 23529 or the test apparatus described in 4.2. lt shall be capable of measuring the test piece thickness to the nearest 0,1 mm. lt shall have plates of diameter at least 30 mm. The dial gauge shall be fitted with a flat contact per
30、pendicular to the plunger and parallel to the base plate and shall operate with a foot pressure of (22 5) kPa.4.2 Compression device for measurement in compressionThe apparatus shall consist of two parallel, flat steel plates, between which the prepared test piece is compressed. In the case of unbon
31、ded test pieces, the plates shall be highly polished with a surface finished to not worse than 0,2 m arithmetic mean deviation from the mean line of the profile. It is recommended that the operating surfaces of the plates be lubricated. The plates shall be sufficiently rigid to withstand the force w
32、ithout bending and of sufficient size to ensure that the whole of the compressed test piece is within the area of the plates.NOTE For most purposes, a silicone or fluorosilicone liquid having a kinematic viscosity of 0,01 m2/s at standard laboratory temperature is a suitable lubricant.One of the pla
33、tes shall be rigidly mounted so that it does not move in any direction under the action of the compressive force. The other plate shall be able to move in a friction-free manner in one direction only, i.e. in a direction coincident with the axis of the test piece (see Figures 1 and 2).The apparatus
34、shall be capable of applying the full force with negligible overshoot and maintaining it constant to within 0,1 %. The mechanism for applying the force shall be such that the line of action of the applied force remains coincident with the axis of the test piece as it creeps.Suitable equipment shall
35、be connected to the compression device so that the deformation of the test piece can be determined, to an accuracy of 0,1 % of the initial test piece thickness, at different times after the force has been fully applied.Many types of apparatus have been used, with mechanical, electronic or optical me
36、asurement of deformation. Figure 2 shows a typical example using a micrometer dial gauge for the determination of creep in compression. The measuring device shall not exert a pressure of more than 22 kPa on the test piece before the test load is applied.If the tests are carried out at an elevated te
37、mperature, the test piece and the flat plates of the compression device shall be inside a temperature-controlled chamber (see 4.4).4.3 Shear device for measurements in shearThe apparatus shall be capable of measuring the shear deflection in the test piece due to the application of a constant shear f
38、orce.The apparatus shall be capable of applying the full force with negligible overshoot and maintaining it constant to within 0,1 %.The force shall be applied either to the central metal plate, with the outer plates rigidly mounted, or to the outer metal plates with the central plate rigidly mounte
39、d. The line of action of the applied force shall be in the plane of the central plate, and pass through its centre in a direction perpendicular to the undeformed rubber test pieces. This line of action shall be maintained as the test piece creeps (see Figure 3).The movement of the central plate rela
40、tive to the outer plates shall be in a friction-free manner and only in the direction of the line of action of the applied force.Suitable equipment shall be connected to the test piece so that relative movement of the central plate with respect to the outside plates can be determined with an accurac
41、y of 0,01 mm at different times after the force has been fully applied.2 ISO 2012 All rights reservedBS ISO 8013:2012ISO 8013:2012(E)Key1 steel plates2 test piece3 line of action of compressive force0initial thicknessFigure 1 Test piece in compressionIf the tests are carried out at an elevated tempe
42、rature, the test piece and the flat plates to which it is bonded shall be inside a temperature-controlled chamber (see 4.4).Figure 4 shows a typical shear test fixture.4.4 Temperature-controlled chamberIf the tests are to be carried out at an elevated temperature, a test chamber shall be used, const
43、ructed in accordance with ISO 23529, and provided with temperature control to maintain the specified air temperature within the tolerances given in Clause 9. Satisfactory circulation of the air shall be achieved by means of a fan. Care shall be taken to minimize change in temperature of the test pie
44、ce by conduction through metal parts which are connected with the outside of the chamber or by direct radiation from heaters within the chamber.4.5 TimerUse a timer reading in seconds and minutes. ISO 2012 All rights reserved 3BS ISO 8013:2012ISO 8013:2012(E)Key1 dial gauge2 locking lever3 setting r
45、ing4 temperature-controlled chamber5 test piece6 ceramic barFigure 2 Example of test arrangement for creep in compression with temperature-controlled chamber4 ISO 2012 All rights reservedBS ISO 8013:2012ISO 8013:2012(E)Key1 steel plates2 bonded test pieces3 line of action of shear force0initial thic
46、knessFigure 3 Test piece in shear ISO 2012 All rights reserved 5BS ISO 8013:2012ISO 8013:2012(E)Key1 actuator2 load cellaShall be in test chamber.Figure 4 Typical test fixture for double-shear test piece6 ISO 2012 All rights reservedBS ISO 8013:2012ISO 8013:2012(E)5 CalibrationThe test apparatus sha
47、ll be calibrated in accordance with the schedule given in Annex B.6 Test piece6.1 Test piece for measurements in compression6.1.1 The test piece shall be a cylindrical disc; two sizes may be used having the following dimensions: Type A shall have a diameter of (29,0 0,5) mm and a thickness of (12,5
48、0,5) mm. Type B shall have a diameter of (13,0 0,5) mm and a thickness of (6,3 0,3) mm.NOTE These sizes correspond to type A and B test pieces in ISO 815-11.6.1.2 The test pieces shall be prepared in accordance with ISO 23529 by either moulding or cutting. They shall be free from any fabric or other
49、 reinforcing support.Cutting shall be carried out by means of a sharp rotating circular die or revolving knife, lubricated with soapy water, and brought carefully into contact with the rubber. Alternatively, the die or knife may be kept stationary and the rubber rotated against it.NOTE When cupping is a problem, the test piece shape can be improved by cutting the test piece in two stages: first cut an oversized test piece and then trim it to the exact dimensions with a second cutter.
