CEN/TS 15880:2009
(Main)Advanced technical ceramics - Ceramic composites - Determination of the fibre/matrix interfacial frictional shear stress at room temperature by a single fibre push-out method
Advanced technical ceramics - Ceramic composites - Determination of the fibre/matrix interfacial frictional shear stress at room temperature by a single fibre push-out method
This CEN Technical Specification specifies a single fibre push-out method to determine the fibre-matrix
bonding 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) and tridirectional (xD, with 2 < x ≤ 3).
Hochleistungskeramik - Keramische Verbundwerkstoffe - Bestimmung der Reibschubspannung an der Grenzfläche Faser/Matrix bei Raumtemperatur mit Hilfe des Einzelfaser-Push-out-Verfahrens
Diese Technische Spezifikation des CEN legt für Verbundwerkstoffe mit keramischer Matrix ein Verfahren (Ausdrückverfahren, Push out Verfahren, Indentations Verfahren) zur Ermittlung der Kennwerte für den Ver-bund zwischen Faser und Matrix fest, indem bei Raumtemperatur eine Einzelfaser aus der Matrix so heraus¬gedrückt wird, dass die Reibschubspannung an der Grenzfläche (reibungsbedingte Scherspannung) zu messen ist.
Diese Norm gilt für alle Verbundwerkstoffe mit keramischer Matrix und kontinuierlicher Faserverstärkung unabhängig davon, ob eine unidirektionale (1D), bidirektionale (2D) oder dreidirektionale (xD, mit 2 < x 3) Faserverstärkung vorliegt.
Céramiques techniques avancées - Céramiques composites - Détermination de la contrainte de frottement en cisaillement à l'interface fibre/matrice à température ambiante - Méthode d'extraction d'une fibre par indentation
La présente Spécification technique du CEN spécifie une méthode d’extraction d’une fibre par indentation permettant de déterminer les caractéristiques de cohésion fibre/matrice des matériaux composites à matrice céramique, à température ambiante, en mesurant la contrainte de frottement en cisaillement à l’interface fibre/matrice.
Elle s’applique à tous les composites à matrice céramique renforcée de fibres en continu, que le renfort soit de type unidirectionnel (1D), bidirectionnel (2D) ou tridirectionnel (xD, pour 2 < x <= 3).
Sodobna tehnična keramika - Keramični kompoziti - Ugotavljanje strižne sile vlakna/matrice pri sobni temperaturi z metodo potiska (push-out method)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2009
6RGREQDWHKQLþQDNHUDPLND.HUDPLþQLNRPSR]LWL8JRWDYOMDQMHVWULåQHVLOH
YODNQDPDWULFHSULVREQLWHPSHUDWXUL]PHWRGRSRWLVND SXVKRXWPHWKRG
Advanced technical ceramics - Ceramic composites - Determination of the fibre/matrix
interfacial frictional shear stress at room temperature by a single fibre push-out method
Hochleistungskeramik - Keramische Verbundwerkstoffe - Bestimmung der
Reibschubspannung an der Grenzfläche Faser/Matrix bei Raumtemperatur mit Hilfe des
Einzelfaser-Push-out-Verfahrens
Céramiques techniques avancées - Céramiques composites - Détermination de la
contrainte de frottement en cisaillement à l'interface fibre/matrice à température
ambiante - Méthode d'extraction d'une fibre par indentation
Ta slovenski standard je istoveten z: CEN/TS 15880:2009
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL SPECIFICATION
CEN/TS 15880
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
May 2009
ICS 81.060.30
English Version
Advanced technical ceramics - Ceramic composites -
Determination of the fibre/matrix interfacial frictional shear stress
at room temperature by a single fibre push-out method
Céramiques techniques avancées - Céramiques Hochleistungskeramik - Keramische Verbundwerkstoffe -
composites - Détermination de la contrainte de frottement Bestimmung der Reibschubspannung an der Grenzfläche
en cisaillement à l'interface fibre/matrice à température Faser/Matrix bei Raumtemperatur mit Hilfe des Einzelfaser-
ambiante - Méthode d'extraction d'une fibre par indentation Push-out-Verfahrens
This Technical Specification (CEN/TS) was approved by CEN on 27 March 2009 for provisional application.
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 their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly 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 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, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2009 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 15880:2009: E
worldwide for CEN national Members.
CEN/TS 15580:2009 (E)
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 Choice of the thickness of the test specimen . 10
9 Test procedure . 10
9.1 Measurement of the fibre length, L . 10
f
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 of the fibre length L for wedge and small angle test
f
specimens . 13
A.1 Wedge test specimen . 13
A.2 Small angle test specimen . 13
Bibliography . 15
Foreword
This document (CEN/TS 15880:2009) has been prepared by Technical Committee CEN/TC 184 “Advanced
technical 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/CENELEC 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, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
CEN/TS 15580:2009 (E)
1 Scope
This CEN Technical Specification specifies a single fibre push-out method to determine the fibre-matrix
bonding 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) and 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) 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 following apply.
3.1
fibre perimeter
p
perimeter of the fibre
3.2
length of the fibre
L
f
embedded 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
F
plateau
compressive force on the fibre determined at point "d" of the curve
3.5
interfacial frictional shear stress
ττf
ττ
shear stress during fibre sliding through the matrix
3.6
fibre top displacement
δδ
δδ
displacement of the top of the fibre during the test
4 Principle
Tests specimens of specific sizes 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 recorded simultaneously (see Figure 1). The dimensions of the fibre pushed shall be determined.
Key
1 Force
2 Indentor
3 Selected fibre
4 Matrix
5 Displacement
Figure 1 – Schematic diagram illustrating the principle of the test
CEN/TS 15580:2009 (E)
Y
c
d
e
b
a
X
Key
X Displacement
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,
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 interfacial characteristics are determined using
the plateau force “d-e”.
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 bond 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 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 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 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 enough, 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 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 transfer 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. 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 extracted 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, clamping 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 calculated 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 determination of the interfacial frictional shear stress. This can be generally performed when
appropriate thick
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