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SIST-TS CEN/TS 15881:2009
01-september-2009
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Advanced technical ceramics - Ceramic composites - Determination of the fibre/matrix
interfacial frictional shear stress at room temperature by tensile tests on mini-composites
Hochleistungskeramik - Keramische Verbundwerkstoffe - Bestimmung der
Reibschubspannung an der Grenzfläche Faser/Matrix bei Raumtemperatur mit Hilfe von
Zugversuchen an Mini-Verbundwerkstoffen
Céramiques techniques avancées - Céramiques composites - Détermination de la
contrainte de frottement en cisaillement à l'interface fibre/matrice à température
ambiante - Essais de traction sur minicomposites
Ta slovenski standard je istoveten z: CEN/TS 15881:2009
ICS:
81.060.30 Sodobna keramika Advanced ceramics
SIST-TS CEN/TS 15881:2009 en,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN/TS 15881:2009
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SIST-TS CEN/TS 15881:2009
TECHNICAL SPECIFICATION
CEN/TS 15881
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 tensile tests on mini-composites
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 von
ambiante - Essais de traction sur minicomposites Zugversuchen an Mini-Verbundwerkstoffen
This Technical Specification (CEN/TS) was approved by CEN on 28 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 15881:2009: E
worldwide for CEN national Members.
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SIST-TS CEN/TS 15881:2009
CEN/TS 15881:2009 (E)
Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms, definitions and symbols .4
4 Principle .6
4.1 Method A .6
4.2 Method B .7
5 Significance and use .7
6 Apparatus .8
6.1 Test machine .8
6.2 Load train .8
6.3 Data recording system .8
7 Test specimens .8
8 Test specimen preparation .9
8.1 General .9
8.2 Window type specimen .9
8.3 Cylindrical end type specimen . 10
9 Number of test specimens . 10
10 Test procedure . 10
10.1 Determination of the gauge length . 10
10.2 Determination of the cross section area . 10
10.3 Determination of the fibre volume fraction . 10
10.4 Determination of the matrix volume fraction . 10
10.5 Determination of the number of cracks at saturation, N . 10
11 Testing technique . 11
12 Test validity . 11
13 Calculations . 11
13.1 Tensile stress . 11
13.2 Method A . 12
13.3 Method B . 12
14 Test report . 15
Bibliography . 16
2
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SIST-TS CEN/TS 15881:2009
CEN/TS 15881:2009 (E)
Foreword
This document (CEN/TS 15881:2009) 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.
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SIST-TS CEN/TS 15881:2009
CEN/TS 15881:2009 (E)
1 Scope
This CEN Technical Specification specifies a 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 obtained by cycled tension on mini-composites.
A mini-composite is a unidirectional composite reinforced with a single tow.
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
EN ISO 7500-1, Metallic materials — Verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Verification and calibration of the force measuring system (ISO
7500-1:2004)
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 radius
Rf
for circular fibres Rf is the mean radius of the fibres; for non circular fibres, Rf is replaced by
S
F
π
3.2
fibre cross-section area
S
F
mean cross section area of the fibre
3.3
cross section area
A
0
cross section area of the test specimen
3.4
gauge length
L
0
initial distance between the two gripped ends of the test specimen
3.5 Volume fraction
3.5.1
fibre volume fraction
V
f
fraction of fibre content in the test specimen that can be determined using microscopy and image analysis or
any other adequate method
4
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3.5.2
matrix volume fraction
V
m
fraction of matrix content in the test specimen that can be determined using microscopy and image analysis or
any other adequate method
3.6
tensile force
F
tensile force on the test specimen
3.7
maximum tensile force
F
M
highest recorded tensile force on the test specimen when tested to failure
3.8
initial tensile force at unloading
F
p
tensile force on the test specimen at initiation of unloading
3.9
tensile force at matrix crack saturation
F
s
tensile force on the test specimen at the end of the non linear domain of the force-displacement curve (see
Figure 1)
3.10
cycle or hysteresis loop
force-displacement curve obtained when loading the test specimen up to a given defined load and then
unloading it to zero load (see Figure 2)
3.11
area of the hysteresis loop
S
area comprised between the unloading and the reloading force-displacement curve during a cycle (see
Figure 2)
3.12
width of a hysteresis loop
δδ∆δδ∆∆∆
difference in measured displacements on unloading and reloading, at a same force, during a cycle (see
Figure 2)
3.13
tensile stress
σσσσ
tensile force in the unloading-reloading sequence that corresponds to δ∆ divided by the cross section area A
o
3.14
initial stress at unloading
σσσσ
p
tensile force at initiation of unloading divided by the cross section area A
o
3.15
stress at matrix crack saturation
σσσσ
s
tensile force at the end of non linear domain of the monotonic loaded force-displacement curve, divided by the
cross-section area A (force level F in Figure 1)
o s
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3.16
longitudinal deformation
∆∆∆∆L
increase of the gauge length under a given force
3.17
total compliance
C
t
inverse of the slope in the initial linear part of the force/displacement curve
3.18
load train compliance
C
l
ratio of the cross-head displacement to the force excluding any test specimen contribution to the
corresponding force during the tensile test
3.19
interfacial frictional shear stress
ττττf
interfacial frictional shear stress at initiation of sliding between fibre and matrix
3.20
mean spacing distance of matrix cracks
l
s
mean spacing distance between transverse cracks after matrix cracking saturation
4 Principle
The mini-composite is loaded monotonically in tension parallel to the fibre direction at a constant displacement
rate.
4.1 Method A
If saturation of matrix cracking can be detected on the force-displacement curve, then the interfacial frictional
shear stress is obtained from the force at crack saturation, F (see Figure 1).
s
Y
X
Key
X Displacement
Y Force
Figure 1 – Force-displacement curve obtained during a tensile test (Method A)
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4.2 Method B
If crack saturation cannot be detected, tensile test shall be performed with unloading/reloading cycles with
increasing force amplitude. The area or the width of the hysteresis loops is directly related to the interfacial
frictional shear stress (see Figure 2).
Y
1 000
900
800
700
1
600
500
2
400
δ∆
300
200
100
0 X
0,7 1
0,1 0,2 0,3 0,5 0,6 0,8 0,9
0 0,4
Key
X Displacement (mm)
Y Force (N)
1 reloading
2 unloading
Figure 2 – Schematic diagram showing loading-unloading cycles (hysteresis loops) obtained during a
tensile test (Method B)
5 Significance and use
Ceramic matrix composites display non-brittle behaviour under tensile loading conditions only when the
fibre/matrix bond is carefully designed. It is essential that the fibre matrix bond is not too strong, which would
cause the composite to be brittle. It should also not be too weak, which would cause the composite to be
unable to withstand high stresses. Interfaces must exhibit a certain resistance to cracking to allow, firstly,
matrix crack arrest and damage tolerance, and secondly, load transfers from the fibre to the matrix.
Characteristics of fibre/matrix interfaces are therefore of primary importance in composite engineering, in
composite evaluation and in prediction of behaviour and performance.
A mini-composite is a unidirectional composite reinforced with a bundle of parallel fibres. Mini-composites are
a simplification of composites. They contain the basic constituents of composites and their response under
load is not obscured by texture effects. They are thus used in the investigation of microstructure-property
relationships in textile composites and in the determination of interface characteristics.
The important characteristic in the mechanical beha
...