BS-ISO-18872-2007.pdf
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1、BRITISH STANDARD BS ISO 18872:2007 Plastics Determination of tensile properties at high strain rates ICS 83.080.10 ? Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 18872:2007 This British Standard was p
2、ublished under the authority of the Standards Policy and Strategy Committee on 31 May 2007 BSI 2007 ISBN 978 0 580 50814 1 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 18872:2007. The UK participation in its preparation was entrusted to Technical C
3、ommittee PRI/21, Testing of plastics. 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 correct application. Compliance with a Briti
4、sh Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 18872:2007(E) INTERNATIO
5、NAL STANDARD ISO 18872 First edition 2007-02-15 Plastics Determination of tensile properties at high strain rates Plastiques Dtermination des proprits en traction hautes vitesses de dformation BS ISO 18872:2007 BS ISO 18872:2007 Licensed Copy: London South Bank University, London South Bank Universi
6、ty, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Principle. 1 4 Terms a
7、nd definitions. 1 5 Apparatus 2 5.1 Test assembly. 2 5.2 Extensometers 2 5.3 Data-recording equipment. 2 6 Test specimens. 2 6.1 Low-strain measurements . 2 6.2 High-strain measurements 2 7 Conditioning 3 8 Test procedure 3 8.1 General. 3 8.2 Test speeds . 3 8.3 Recording of data . 3 9 Calculation a
8、nd expression of results 3 9.1 Low-strain measurements . 3 9.2 High-strain measurements 4 10 Modelling stress versus plastic strain curves. 6 10.1 Low-strain measurements . 6 10.2 High-strain measurements 6 11 Determination of properties over a wide range of strain rates 6 11.1 Tensile modulus 6 11.
9、2 Stress/plastic strain curves. 6 12 Precision 7 Annex A (informative) Modelling true stress against true plastic strain curves: Low-strain measurements. 8 Annex B (informative) Modelling true stress against true plastic strain curves: High-strain measurements 11 BS ISO 18872:2007 Licensed Copy: Lon
10、don South Bank University, London South Bank University, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International
11、 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, governmental and non-governmental, in liaison with ISO, a
12、lso 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 Directives, Part 2. The main task of technical commit
13、tees 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 bodies casting a vote. Attention is drawn to the pos
14、sibility 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 18872 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical properties. BS ISO 18872:2007 Lic
15、ensed Copy: London South Bank University, London South Bank University, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Plastics Determination of tensile properties at high strain rates 1 Scope This International Standard specifies procedures for determining the tensile properties o
16、f moulding and extrusion plastics over a wide range of strain rates, including high rates appropriate to impact-loading situations. Properties are determined through a combination of measurements at low and moderate strain rates, the use of mathematical functions to model these results, the rate-dep
17、endence of parameters and the determination of parameters at high strain rates by extrapolation. Tensile properties at high strain rates are then derived by calculation. In this way, the experimental problems and associated errors with the measurement of properties at high rates are avoided. The mea
18、surement of properties at low and moderate strain rates is based on ISO 527-2, which identifies the types of plastics materials to which this International Standard is applicable. 2 Normative references The following referenced documents are indispensable for the application of this document. For da
19、ted references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 527-1:1993, Plastics Determination of tensile properties Part 1: General principles ISO 527-2, Plastics Determination of tensile properties Pa
20、rt 2: Test conditions for moulding and extrusion plastics ISO 2818, Plastics Preparation of test specimens by machining 3 Principle Tensile stress versus strain curves are measured in accordance with ISO 527-2 at selected speeds in the range 0,1 mm/s to 100 mm/s. In order to maximize the accuracy of
21、 these results at the higher speeds, it is necessary to pay attention to certain features of the design of the test assembly as described in Clause 5. Measurements are also made of the variation of Poissons ratio with strain. From these results, values of true stress and true plastic strain are calc
22、ulated at each strain rate. A mathematical function is used to accurately model the shape of each stress/plastic strain curve. The variation of parameters in this function with strain rate is also modelled to enable the values of parameters at higher strain rates to be determined by extrapolation. S
23、tress/strain curves at these higher strain rates can then be derived by calculation. 4 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 527-1 and the following apply. BS ISO 18872:2007 Licensed Copy: London South Bank University, London South Bank Unive
24、rsity, Fri Jun 01 01:46:04 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 4.1 true stress T force divided by the cross-sectional area of the specimen within the gauge length at the same time as the force is measured 4.2 true strain T incremental increase in the gauge length divided by the gauge length
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