1、BSI Standards PublicationBS ISO 17138:2014Fine ceramics (advancedceramics, advanced technicalceramics) Mechanicalproperties of ceramiccomposites at roomtemperature Determinationof flexural strengthBS ISO 17138:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of IS
2、O 17138:2014.The UK participation in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a
3、contract. Users are responsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 77170 5ICS 81.060.30Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the a
4、uthority of theStandards Policy and Strategy Committee on 30 November 2014.Amendments issued since publicationDate Text affectedBS ISO 17138:2014 ISO 2014Fine ceramics (advanced ceramics, advanced technical ceramics) Mechanical properties of ceramic composites at room temperature Determination of fl
5、exural strengthCramiques techniques Proprits mcaniques des composites cramiques temprature ambiante Dtermination de la resistance en flexionINTERNATIONAL STANDARDISO17138First edition2014-12-01Reference numberISO 17138:2014(E)BS ISO 17138:2014ISO 17138:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT
6、 PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission.
7、 Permission can be requested 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. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 17138:2014ISO 171
8、38:2014(E)Contents PageForeword .iv1 Scope . 12 Normative references 13 Terms, definitions, and symbols 14 Principle 25 Apparatus . 25.1 Test machine . 25.2 Test fixture 25.3 Data recording system 25.4 Dimension measuring devices . 26 Test specimens 27 Test specimen preparation 37.1 Machining and pr
9、eparation 37.2 Number of test specimens . 38 Test procedures . 48.1 Displacement rate 48.2 Measurement of dimensions . 48.3 Testing technique 48.4 Test validity 48.5 Calculation of results . 59 Test report . 6Bibliography 8 ISO 2014 All rights reserved iiiBS ISO 17138:2014ISO 17138:2014(E)ForewordIS
10、O (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO 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 co
11、mmittee 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 in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electro
12、technical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was draf
13、ted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). 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 ri
14、ghts. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not const
15、itute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe com
16、mittee responsible for this document is ISO/TC 206, Fine ceramics.iv ISO 2014 All rights reservedBS ISO 17138:2014Fine ceramics (advanced ceramics, advanced technical ceramics) Mechanical properties of ceramic composites at room temperature Determination of flexural strength1 ScopeThis International
17、 Standard describes a method for the determination of the flexural strength of ceramic matrix composite materials with continuous fibre reinforcement, under three-point or four-point bend at room temperature. This method applies to all ceramic matrix composites with a continuous fibre reinforcement,
18、 unidirectional (1D), bidirectional (2D), and tridirectional xD with (2 x 3) as defined in CEN/TR 13233, loaded along one principal axis of reinforcement.NOTE The method is not intended to be used to obtain absolute values of strength for design purposes.2 Normative referencesThe following documents
19、, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 7500-1, Metallic materials
20、Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring systemISO 3611, Geometrical product specifications (GPS) Dimensional measuring equipment: Micrometers for external measurements Design and metrological ch
21、aracteristicsCEN/TR 13233: 2007, Advanced technical ceramics Ceramic composites Notations and symbols3 Terms, definitions, and symbolsFor the purposes of this document, the terms and definitions given in CEN/TR 132331)and the following apply.3.1maximum flexural forceFmhighest recorded force in a fle
22、xural test on the test specimen when tested to failure3.2flexural stressnominal stress on the outer surface of the test specimen, calculated at mid-spanNote 1 to entry: This stress is conventionally calculated according to the beam theory, whose basic assumptions cannot be met by ceramic matrix comp
23、osite materials.3.3flexural strengthf,mmaximum flexural stress applied to a test specimen that fractures during a flexural test1) An International Standard, ISO 19634, Fine ceramics (advanced ceramics, advanced technical ceramics) Notations and symbols of ceramic composites is under preparation.INTE
24、RNATIONAL STANDARD ISO 17138:2014(E) ISO 2014 All rights reserved 1BS ISO 17138:2014ISO 17138:2014(E)4 PrincipleA beam is supported on two outer points, and subjected to an external load applied perpendicularly to a longitudinal axis. The test is performed at constant crosshead displacement rate.5 A
25、pparatus5.1 Test machineThe machine shall be equipped with a system for measuring the force applied to the test specimen. The system shall conform to grade 1 according to ISO 7500-1.5.2 Test fixtureThe test fixture is composed of two parts, linked to the fixed and mobile parts of the machine. It has
26、 two outer support rollers and one (three-point bend) or two (four-point bend) inner rollers for application of load.The cylindrical rollers shall have a diameter between 4 mm and 10 mm. Their length shall be at least equal to the width of the test specimen. They shall be made of a material with har
27、dness at least equal to that of the test specimen. The axes of the rollers shall be parallel to within 0,01 mm/mm. (See Figure 1.)Pivoting rollers may be used to adapt the non-parallelism of the upper and lower faces of un-machined test specimens. Either two or three rollers, for three-point or four
28、-point bend, respectively, shall be free to pivot around an axis parallel to the longitudinal direction of the test specimen.The distance between rollers shall be in accordance with Clause 6.The inner rollers shall be centred with respect to the outer rollers to within 0,2 mm. In case of four-point
29、bend, the test fixture shall ensure symmetrical loading of the test specimen.5.3 Data recording systemA calibrated recorder shall be used to record the force-time curve. The use of a digital data recording system is recommended.5.4 Dimension measuring devicesDevices used for measuring linear dimensi
30、ons of the test specimen shall be accurate to 0,1 mm. Micrometers shall be in accordance with ISO 3611.6 Test specimensRecommended test specimen dimensions are given in Table 1. These dimensions have been successfully used and take into account the following factors.The volume of material under load
31、 shall be representative of the nature of the material and of the reinforcement structure. This sets minimum limits to the span and to the width and thickness of the test specimen. In case of flexural, as opposed to tensile, testing, the distribution of the longitudinal reinforcement through the thi
32、ckness has to be considered. When this distribution is not symmetrical with respect to the neutral plane, care shall be taken to ensure that it is similar for all test specimens.Two types of test specimens can be distinguished as follows:a) as fabricated test specimens, where only the length and the
33、 width are machined to give to the test specimens the specified size. In this case, the tensile and compressive surfaces can be unmachined and thus irregular;2 ISO 2014 All rights reservedBS ISO 17138:2014ISO 17138:2014(E)b) machined test specimens, where the length, the width, and the thickness of
34、the test specimen have been machined.Tolerance on thickness is only for machined test specimens. For as fabricated test specimens, the maximum difference in thickness of three measurements (at the centre and at each end of the outer span length) shall not exceed 5 % of the average of the three measu
35、rements.The thickness of the test specimen and the distance between the inner and outer roller(s) shall be chosen so as to avoid shear failure. This is achieved by setting a minimum limit to the ratio between the moment arm and the test specimen thickness (see Table 1). A value of 10 is commonly use
36、d and translates into a minimum L/h ratio of 20 in three-point bend, and a minimum (L-Li)/h ratio of 20 in four-point bend with Li= L/3.Table 1 Recommended test specimen and span dimensionsDimensions in millimetres1D, 2D, xD Tolerancelt, total length L + 20 1b, width 10 0,2h, mean thickness of test
37、specimen 2 0,2Inner span25 0,1Li, four-point bendOuter span75 0,1L, four-point bendL, three-point bend 50 0,1If it is necessary to define test specimens of different dimensions, the conditions of Clause 6 should be taken into account.7 Test specimen preparation7.1 Machining and preparationDuring cut
38、ting out, care shall be taken to align the longitudinal test specimen axis with one of the principal axes of reinforcement.Test specimens can be tested with either machined or non-machined tensile and compressive surfaces. In some cases machining is not recommended because it might cause damage to t
39、he material near the tensile and compressive surfaces. When machining these surfaces, care shall be taken to maintain reinforcement geometry across the thickness of the test specimen, which is representative of the material in the as-processed condition. In particular, it shall be ensured that the s
40、ymmetry of originally symmetric reinforcement geometry is preserved in the test specimen cross section after machining.Machining parameters which avoid damage to the material shall be established and documented. These parameters shall be adhered to during test specimen preparation.7.2 Number of test
41、 specimensAt least five valid test results (see 8.4) are required.For test specimens with a non-symmetric reinforcement geometry with respect to the neutral plane, tests in two orientations for which the tensile and compressive face are interchanged might be necessary.NOTE If statistical evaluation
42、is required, the number of test specimens should be in accordance with EN 8435. ISO 2014 All rights reserved 3BS ISO 17138:2014ISO 17138:2014(E)8 Test procedures8.1 Displacement rateUse a constant crosshead displacement rate which allows quasi-static loading of test specimen and the absence of subcr
43、itical crack growth. (0,5 0,1) mm/min or a rate which allows test specimen failure in about 1 min is recommended. The displacement rate shall be reported.8.2 Measurement of dimensions8.2.1 Test specimen dimensionsThe width and thickness shall be measured to the nearest 0,01 mm in three points near t
44、he centre for three-point bend and between the inner rollers for four-point bend, and at each end of the test specimen.The arithmetic means of the measurements shall be used for calculations.8.2.2 Distances between supporting rollersThe distance between axes of the outer rollers and for four-point b
45、end also the inner rollers shall be measured to the nearest 0,1 mm.NOTE This can be achieved by the use of a travelling microscope or other suitable device accurate to 0,05 mm.8.3 Testing technique8.3.1 Test specimen mountingThe test specimen shall be installed in the test jig centred with respect t
46、o the rollers and with its longitudinal axis perpendicular to the axes of the rollers.NOTE It is recommended to use a setting tool for this purpose.Zero the load cell output. When required, a small preload can be applied in order to maintain correct positioning of the test specimen. This preload sha
47、ll not increase beyond 5 % of the expected failure force at any time.8.3.2 MeasurementsPerform the measurements as follows: set the displacement rate on the test machine; zero the load cell; record the force versus time; load the test specimen up to failure; read the load signal after test specimen
48、failure; note the position of fracture location relative to the mid-point of the test specimen to the nearest 1 mm and the failure mode (tensile or compressive).8.4 Test validityThe following circumstances invalidate a test: failure to specify and record test conditions;4 ISO 2014 All rights reserve
49、dBS ISO 17138:2014ISO 17138:2014(E) failure to meet specified test conditions; rupture of the test specimen not occurring in the tensile or compressive mode; rupture outside the zone where the bending moment is maximum (i.e. outside the central part, 1/3 L, for three-point bend, and outside the inner span for four-point bend); rupture is initiated under a roller.8.5 Calculation of results8.5.1 General8.5.1.1 Test specimen originA diagram illustrating the reinforcement directions of the material
