BS DD CEN TS 15880-2009 Advanced technical ceramics - Ceramic composites - Determination of the fibre matrix interfacial frictional shear stress at room temperature by a single fib.pdf

1、DD CEN/TS15880:2009ICS 81.060.30NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWDRAFT FOR DEVELOPMENTAdvanced technicalceramics Ceramiccomposites Determination of thefibre/matrix interfacialfrictional shear stressat room temperatureby a single fibre push-out methodThis Draft fo

2、r Developmentwas published under theauthority of the StandardsPolicy and StrategyCommittee on 30 June2009. BSI 2009ISBN 978 0 580 63937 1Amendments/corrigenda issued since publicationDate CommentsDD CEN/TS 15880:2009National forewordThis Draft for Development is the UK implementation of CEN/TS15880:

3、2009.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications andis of a provisional nature. It should be applied on this provisional basis,so that information and experience of its practical application can beobtained.Commen

4、ts arising from the use of this Draft for Development arerequested so that UK experience can be reported to the internationalorganization responsible for its conversion to an international standard.A review of this publication will be initiated not later than 3 years afterits publication by the inte

5、rnational organization so that a decision can betaken on its status. Notification of the start of the review period will bemade in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period,the responsible BSI Committee will decide

6、whether to support theconversion into an international Standard, to extend the life of theTechnical Specification or to withdraw it. Comments should be sent tothe Secretary of the responsible BSI Technical Committee at BritishStandards House, 389 Chiswick High Road, London W4 4AL.The UK participatio

7、n in its preparation was entrusted to TechnicalCommittee RPI/13, Advanced technical ceramics.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible

8、for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.DD CEN/TS 15880:2009TECHNICAL SPECIFICATIONSPCIFICATION TECHNIQUETECHNISCHE SPEZIFIKATIONCEN/TS 15880May 2009ICS 81.060.30English VersionAdvanced technical ceramics - Ceramic composites -Deter

9、mination of the fibre/matrix interfacial frictional shear stressat room temperature by a single fibre push-out methodCramiques techniques avances - Cramiquescomposites - Dtermination de la contrainte de frottementen cisaillement linterface fibre/matrice tempratureambiante - Mthode dextraction dune f

10、ibre par indentationHochleistungskeramik - Keramische Verbundwerkstoffe -Bestimmung der Reibschubspannung an der GrenzflcheFaser/Matrix bei Raumtemperatur mit Hilfe des Einzelfaser-Push-out-VerfahrensThis Technical Specification (CEN/TS) was approved by CEN on 27 March 2009 for provisional applicati

11、on.The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit theircomments, particularly on the question whether the CEN/TS can be converted into a European Standard.CEN members are required to announce the existence of

12、this CEN/TS in the same way as for an EN and to make the CEN/TS availablepromptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)until the final decision about the possible conversion of the CEN/TS into an EN is

13、reached.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, S

14、pain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Memb

15、ers.Ref. No. CEN/TS 15880:2009: EDD CEN/TS 15880:2009CEN/TS 15580:2009 (E) 2 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Terms, definitions and symbols .4 4 Principle 5 5 Significance and use .7 6 Apparatus .7 7 Test specimens 9 8 Test specimen preparation 10 8.1 General . 10 8.2 C

16、hoice of the thickness of the test specimen . 10 9 Test procedure 10 9.1 Measurement of the fibre length, Lf10 9.2 Fibre selection . 10 9.3 Measurements of fibre dimensions 11 9.4 Testing technique . 11 10 Test validity . 11 11 Calculations . 11 12 Test report . 12 Annex A (normative) Determination

17、of the fibre length Lffor wedge and small angle test specimens . 13 A.1 Wedge test specimen . 13 A.2 Small angle test specimen . 13 Bibliography . 15 DD CEN/TS 15880:2009CEN/TS 15880:2009 (E) 3 Foreword This document (CEN/TS 15880:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced t

18、echnical ceramics”, the secretariat of which is held by BSI. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENE

19、LEC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, L

20、uxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DD CEN/TS 15880:2009CEN/TS 15580:2009 (E) 4 1 Scope This CEN Technical Specification specifies a single fibre push-out method to determine the fibre-matrix bonding

21、 characteristics of ceramic matrix composite materials at room temperature, by the measurement of the interfacial frictional shear stress. This standard applies to all continuous fibre-reinforced ceramic matrix composites whatever the type of reinforcement: unidirectional (1D), bidirectional (2D) an

22、d tridirectional (xD, with 2 x 3). 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 document (including any amendments)

23、applies. CEN/TR 13233:2007, Advanced technical ceramics - Notations and symbols ISO 3611, Micrometer callipers for external measurements 3 Terms, definitions and symbols For the purposes of this European Technical Specification, the terms, definitions and symbols given in CEN/TR 13233:2007 and the f

24、ollowing apply. 3.1 fibre perimeter p perimeter of the fibre 3.2 length of the fibre Lfembedded length of the fibre which is equal to the local thickness of the test specimen 3.3 compressive force F compressive force on the fibre 3.4 compressive plateau force Fplateaucompressive force on the fibre d

25、etermined at point “d“ of the curve 3.5 interfacial frictional shear stress f shear stress during fibre sliding through the matrix 3.6 fibre top displacement displacement of the top of the fibre during the test DD CEN/TS 15880:2009CEN/TS 15880:2009 (E) 5 4 Principle Tests specimens of specific sizes

26、 and geometry are used for the tests. A fibre is pushed through the matrix using an indentation tester. A compressive force is applied through an indentor at a constant displacement rate, on top of a single fibre and parallel to fibre axis. The force and the fibre top displacement are measured and r

27、ecorded simultaneously (see Figure 1). The dimensions of the fibre pushed shall be determined. 12345Key 1 Force 2 Indentor 3 Selected fibre 4 Matrix 5 Displacement Figure 1 Schematic diagram illustrating the principle of the test DD CEN/TS 15880:2009CEN/TS 15580:2009 (E) 6 1YX11abc de1Key X Displace

28、ment Y Force Figure 2 Schematic diagram showing a typical single-fibre push-out behaviour for a ceramic matrix composite Figure 2 exhibits the following steps: a b elastic fibre deformation, b initiation of debonding, b c region of progressive (stable) debonding and sliding (push-in), c instability,

29、 c d unstable debonding, d initiation of push-out, d e progressive push-out: stable extraction of the embedded fibre (plateau). The interfacial parameters are extracted from the experimental force versus top-fibre displacement curve. The complete curve “a-e” is obtained by a push-out test, and the i

30、nterfacial characteristics are determined using the plateau force “d-e”. DD CEN/TS 15880:2009CEN/TS 15880:2009 (E) 7 5 Significance and use Ceramic matrix composites display a non-brittle behaviour under tensile loading conditions when the fibre/matrix bond is carefully designed. The fibre/matrix bo

31、nd cannot be too strong, otherwise the composite will be brittle. The fibre/matrix bond cannot be too weak, otherwise the composite will be unable to withstand high stresses. Interfaces must exhibit an appropriate resistance to cracking to allow, first, matrix crack arrest and damage tolerance, and

32、second, load transfers from the fibre to the matrix. Characteristics fibre/matrix interfaces are therefore of primary importance in composite engineering, evaluation and in predictions of behaviour and performances. Fibre pushing tests (and more particularly the single fibre push-out tests) are used

33、 for the determination of fibre/matrix interface characteristics in composites. This is a powerful tool to evaluate those interfaces controlling the mechanical behaviour. The main advantages of fibre push out tests are the relative simplicity of the test procedure and the fact that single fibres can

34、 be selected in the composite. The method of extraction of interface characteristics critically depends on the shape of the force-displacement curve recorded during the tests. When test specimens are too thick only the push-in portion of the curve can be obtained. When the test specimen is thin enou

35、gh, the complete curve depicted in Figure 2 is obtained. The shape of the curve may be additionally influenced by interface strength. In the presence of quite strong interfaces, the push-in curve exhibits an upward curvature. In this case, very thin specimens are required to get fibre push out. The

36、fibre pushing tests allow various characteristics to be determined depending on the portion of the curve considered. The basic data that can be extracted from both the push in and the push out curves, are the interfacial frictional shear stress which measures the ability of a cracked interface to tr

37、ansfer stresses from the fibre to the matrix. In a fibre pushing test, the basic data is given by the shear stress during fibre sliding. The interfaces that are the most efficient from this viewpoint are characterized by high interfacial shear stresses. Such interfaces can be considered to be strong

38、. On the contrary, the less efficient interfaces are characterized by low interface shear stresses. Such interfaces can be considered to be weak. Therefore, the interface shear stress provides an index of interface strength. This characteristic, as well as the resistance to debonding, can be extract

39、ed from both push-in and push-out curves. Extraction of these data from push-in curves relies on quite complex models that can be found in the references in the Bibliography. It is simpler when push-out curves can be produced. However, additional properties such as the coefficient of friction, clamp

40、ing stress, interface roughness could be extracted from the push-in curves. Determination of interface characteristics from the push-in requires the use of complex relations (see bibliography) and will not be treated in this standard. In the case of push-out, the sliding interfacial stress can be ca

41、lculated from the stress of the plateau at point “d” on the curve of Figure 2, where sliding of the fibre starts on along its entire length (that is the thickness of the specimen). Because it requires simpler calculations, the push-out method is the principal experimental method for experimental det

42、ermination of the interfacial frictional shear stress. This can be generally performed when appropriate thickness of the test specimen is selected. In addition to the push-out method described here, there also exist other methods to determine the fibre/matrix bond characteristics: the pull-out techn

43、ique, the tensile tests on mini-composites or composites. Each of these has its relative merits and disadvantages; the selection of an appropriate method has to be considered on a case by case basis. 6 Apparatus The major components that are needed to run a test are a load cell, a displacement-contr

44、olled system equipped with a strain gauge, an indentor, a microscope, a force-displacement recording system, a mobile test specimen holder on a vibration-free table to allow the test specimen to move in the two directions x and y, a system that permits a perfect alignment of the indentor displacemen

45、t axis with the fibre axis, and a data-acquisition system to store experimental results. Following type of indentor is recommended: flat tip indentor DD CEN/TS 15880:2009CEN/TS 15580:2009 (E) 8 with the diameter of the indentor tip smaller than the diameter of the fibre, and made of a material harde

46、r and stiffer than the fibre (for instance diamond). Examples of experimental assemblies that have been successfully employed for this test are shown in Figures 3 and 4. 123985674Key 1 Sighting system optical microscope/video camera 2 Stepping motor 3 Moving table 4 Indentor 5 Load transducer 6 Vibr

47、ation actuator 7 Dilatation device 8 Displacement transducer 9 Sample Figure 3 Experimental set-up of the indentation tester 1 DD CEN/TS 15880:2009CEN/TS 15880:2009 (E) 9 14566723Key 1 Lens 2 Indentor 3 Sample 4 Sample holder 5 Load cell 6 Displacement transducer 7 Lens turret 8 Optical microscope F

48、igure 4 Experimental set-up of the indentation tester 2 7 Test specimens Three test specimen geometries can be used for the tests, which are shown in Figure 5: a) the thin slab geometry (Figure 5a); b) the wedge geometry (Figure 5b); c) the small-angle thin slab geometry (Figure 5c). DD CEN/TS 15880

49、:2009CEN/TS 15580:2009 (E) 10 The choice of the test specimen geometry and dimensions depends on the nature of the material, on the reinforcement structure and on the strength of the fibre-matrix bond. A thin test specimen, as defined in Clause 9.1, is recommended to allow push-out to occur. 1(a) thin slab (b) wedge (c) small-angle thin slab Figure 5 Schematic representation of the different test specimen geometry NOTE Examples of specimen holders are shown in Annex A. 8 Test specimen