SIST EN ISO 20505:2025

SLOVENSKI STANDARD
01-maj-2025
Fina keramika (sodobna keramika, sodobna tehnična keramika) - Mehanske
lastnosti keramičnih kompozitov pri sobni temperaturi - Določevanje medplastne
strižne trdnosti in strižnega modula kompozitov, ojačanih z neprekinjenimi vlakni,
s stiskanjem preizkušancev z dvojnim vrezom in z Iosipescujevim preskusom (ISO
20505:2023)
Fine ceramics (advanced ceramics, advanced technical ceramics) - Mechanical
properties of ceramic composites at room temperature - Determination of the
interlaminar shear strength and shear modulus of continuous-fibre-reinforced composites
by the compression of double-notched test pieces and by the Iosipescu test (ISO
20505:2023)
Hochleistungskeramik - Mechanische Eigenschaften von keramischen
Verbundwerkstoffen bei Raumtemperatur - Bestimmung der Scherfestigkeit und des
Schubmoduls endlosfaserverstärkter Verbundwerkstoffe durch Druckbeanspruchung von
doppeltgekerbten Proben und durch den Iosipescu-Test (ISO 20505:2023)
Céramiques techniques - Propriétés mécaniques des céramiques composites à
température ambiante - Détermination de la résistance au cisaillement interlaminaire et
du module de cisaillement des composites renforcés par des fibres continues, par la
compression d’éprouvettes à double entaille et par l’essai Iosipescu (ISO 20505:2023)
Ta slovenski standard je istoveten z: EN ISO 20505:2025
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 20505
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2025
EUROPÄISCHE NORM
ICS 81.060.30 Supersedes EN 658-4:2003
English Version
Fine ceramics (advanced ceramics, advanced technical
ceramics) - Mechanical properties of ceramic composites
at room temperature - Determination of the interlaminar
shear strength and shear modulus of continuous-fibre-
reinforced composites by the compression of double-
notched test pieces and by the Iosipescu test (ISO
20505:2023)
Céramiques techniques - Propriétés mécaniques des Hochleistungskeramik - Mechanische Eigenschaften
céramiques composites à température ambiante - von keramischen Verbundwerkstoffen bei
Détermination de la résistance au cisaillement Raumtemperatur - Bestimmung der Scherfestigkeit
interlaminaire et du module de cisaillement des und des Schubmoduls endlosfaserverstärkter
composites renforcés par des fibres continues, par la Verbundwerkstoffe durch Druckbeanspruchung von
compression d'éprouvettes à double entaille et par doppeltgekerbten Proben und durch den Iosipescu-
l'essai Iosipescu (ISO 20505:2023) Test (ISO 20505:2023)
This European Standard was approved by CEN on 24 February 2025.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20505:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 20505:2023 has been prepared by Technical Committee ISO/TC 206 "Fine ceramics” of
the International Organization for Standardization (ISO) and has been taken over as EN ISO 20505:2025
by Technical Committee CEN/TC 184 “Advanced technical ceramics” the secretariat of which is held by
DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2025, and conflicting national standards shall
be withdrawn at the latest by August 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 658-4:2003.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 20505:2023 has been approved by CEN as EN ISO 20505:2025 without any modification.

INTERNATIONAL ISO
STANDARD 20505
Second edition
2023-10
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Mechanical properties of ceramic
composites at room temperature —
Determination of the interlaminar
shear strength and shear modulus
of continuous-fibre-reinforced
composites by the compression of
double-notched test pieces and by the
Iosipescu test
Céramiques techniques — Propriétés mécaniques des céramiques
composites à température ambiante — Détermination de la
résistance au cisaillement interlaminaire et du module de cisaillement
des composites renforcés par des fibres continues, par la compression
d’éprouvettes à double entaille et par l’essai Iosipescu
Reference number
ISO 20505:2023(E)
ISO 20505:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 20505:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 4
4.1 General . 4
4.2 Double-notched test . 4
4.3 Iosipescu test . 4
5 Apparatus . 5
5.1 Test machine . 5
5.2 Load train . 5
5.2.1 Generalities . 5
5.2.2 Test fixtures . 6
5.3 Strain gauges for Iosipescu test specimen . 8
5.4 Data acquisition . 9
5.5 Dimension-measuring devices . 9
6 Test specimens . 9
6.1 Double-notched test piece . 9
6.2 Iosipescu test piece . 11
7 Test specimen preparation .12
7.1 Machining and preparation . 12
7.2 Bonding of the gauges . 12
7.3 Number of test specimens .12
8 Test procedures .12
8.1 Displacement rate .12
8.2 Measurement of test specimen dimensions . 13
8.3 Testing technique . 13
8.3.1 Specimen mounting . 13
8.3.2 Measurements . 14
8.4 Test validity . 15
9 Calculation of results .16
9.1 Shear strength . 16
9.1.1 Double-notched test piece . 16
9.1.2 Iosipescu test piece . 16
9.2 Shear strain (Iosipescu test) . 17
9.3 Shear-stress-shear-strain curves . 17
9.4 Elastic shear modulus, pseudo-elastic shear modulus . 17
9.5 Statistics . 18
10 Report .18
Annex A (informative) New materials: verification of shear stress field in the Iosipescu test .20
Bibliography .21
iii
ISO 20505:2023(E)
Foreword
ISO (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
committee 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
electrotechnical 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 document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
This second edition cancels and replaces the first edition (ISO 20505:2005), which has been technically
revised.
The main changes are as follows:
— Scope revised to include the possibility of measuring the interlaminar shear modulus through the
use of a gauges-instrumented Iosipescu sample;
— new entries added to Clause 3;
— 5.3 and 7.2 specify requirements on the gauges-instrumented Iosipescu sample;
— 9.3, 9.4 and 9.5 define formulae to determine the shear modulus;
— material orientation added to Figure 2 and Figure 3;
— subclause on test validity added (8.4);
— Table 1 and Table 2 updated;
— Annex A replaced by a method to verify the shear stress field in the Iosipescu test to ensure that that
there are no coupling effects that make this document unsuitable for determining the interlaminar
shear properties of the material;
— minor editorial corrections;
— structure revised;
— symbols and notation modified in accordance with ISO 19634.
iv
ISO 20505:2023(E)
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
INTERNATIONAL STANDARD ISO 20505:2023(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at room temperature — Determination of the interlaminar
shear strength and shear modulus of continuous-fibre-
reinforced composites by the compression of double-
notched test pieces and by the Iosipescu test
1 Scope
This document specifies a method for the determination of interlaminar shear strength at ambient
temperature by the compression of a double-notched test piece and a method for the determination of
interlaminar shear strength and modulus at ambient temperature by the Iosipescu test. This document
applies to all ceramic matrix composites with a continuous fibre reinforcement, having unidirectional
(1D), bidirectional (2D) and multidirectional (xD, with x > 2) fibre architecture, where a major part of
reinforcements is a stack of plies.
This document is applicable to material development, material comparison, quality assurance,
characterization, reliability and design data generation. The simpler compression test method of a
double-notched test piece is applicable only when the shear strength has to be measured.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 3611, Geometrical product specifications (GPS) — Dimensional measuring equipment: Micrometers for
external measurements — Design and metrological characteristics
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 17161, Fine ceramics (advanced ceramics, advanced technical ceramics) — Ceramic composites —
Determination of the degree of misalignment in uniaxial mechanical tests
ISO 19634, Fine ceramics (advanced ceramics, advanced technical ceramics) — Ceramic composites —
Notations and symbols
ISO 20507, Advanced ceramics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20507 and ISO 19634 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
ISO 20505:2023(E)
3.1
shear section
section located between the notches of test sample
Note 1 to entry: Due to the orientation of the test sample (see Figures 2 and 3), the shear plane is orthogonal to
direction 3 and parallel to the stack of plies (plane 1, 2). Therefore, the shear mechanism occurs between the
composite plies and the resulting shear properties, with respect to the definition given in ISO 20507, are labelled
as “interlaminar”.
3.2
initial shear section area
S
shear section area before test between the notches of the test piece at room temperature
3.3
shear section area
S
e
effective shear loaded section area of the test piece at room temperature
Note 1 to entry: This effective shear loaded section area is determined when a valid failure occurs in a plane
parallel to the shear plane in an Iosipescu test sample.
3.4
shear force
F
force parallel to the shear section carried by the test specimen at any time during the shear test
Note 1 to entry: See Figure 1.
Key
F shear force L height of the cubic element
γ shear strain δ displacement
Figure 1 — Shear force and shear strain
3.5
maximum shear force
F
m
maximum force parallel to the shear section during a test or at fracture
ISO 20505:2023(E)
3.6
interlaminar shear strength
σ
ILSS,m,i,3
ratio of the maximum shear force to the initial shear section area
Note 1 to entry: With respect to the material orientation defined in ISO 19634, subscript “i” is for the direction of
the load with respect to the material orientation and subscript “3” is for the material orientation orthogonal to
the shear plan (see Figures 2 and 3).
3.7
shear strain
γ
change in angle between two adjacent sides of a cubic-shaped stress element submitted to a shear force
Note 1 to entry: Although shear strain is defined as an angle, for small strains this measure becomes the ratio of
displacement δ to the height of the stress element L (see Figure 1).
3.8
strain
ε
ij
ε
θ
ratio of deformation to initial strain gauge length
Note 1 to entry: The subscripts "ij" and "θ" indicate the orientation of the strain gauge with respect to test sample
orientation.
3.9
shear stress
σ
ILSS i,3
ratio of the shear force to the initial shear section area at any time during the test
Note 1 to entry: With respect to the material orientation defined in ISO 19634, subscript “i” is for the direction of
the load with respect to the material orientation and subscript “3” is for the material orientation orthogonal to
the shear plan (see Figures 2 and 3).
3.10
measurement zone
part of the test piece, in the plane perpendicular to direction 1 or 2 (see Figures 2 and 3), between the
notches
3.11
elastic shear modulus
G
i,3
ratio of shear stress to corresponding shear strain
Note 1 to entry: For general use the reference plane for G is defined by the axes i and 3.
i,3
Note 2 to entry: If the plane is defined by the normal axis, the elastic modulus is noted G .
i
3.12
pseudo-elastic shear modulus
G
p,i,3
slope of the linear section not starting from the origin of the shear-stress-shear-strain curve, if any
G is defined as the proportionality ratio:
p,i,3
′′ ′
σ−σ
′″ ILSS ILSS
G=σσ
()
p,i,3ILSS, ILSS
″′
γ−γ
where (γ’, σ’ ) and (γ’’, σ’’ ) lie on the linear section of the shear-stress-shear-strain curve
ILSS ILSS
Note 1 to entry: For general use the reference plane for G is defined by the axes i and 3.
p,i,3
ISO 20505:2023(E)
Note 2 to entry: If the plane is defined by the normal axis, the elastic modulus is noted G .
pi
Note 3 to entry: For material with nonlinear shear stress-strain behaviour, only stress-strain couples can be
fixed.
4 Principle
4.1 General
The interlaminar shear strength of continuous-fibre reinforced ceramic composites, as determined by
this document, can be measured by the compression of double-notched test pieces or by the Iosipescu
test. The interlaminar shear modulus shall be measured by the Iosipescu test.
NOTE The test is performed at constant displacement rate, up to failure.
4.2 Double-notched test
A double-notched test piece of uniform width is loaded in compression to induce failure by shear
between two centrally located notches machined halfway through the thickness and spaced a fixed
distance apart on opposing faces (see Figure 2).
NOTE Some attempts to measure shear strain and shear modulus on a double-notched test piece with the
use of a virtual strain gauge through digital image correlation analysis have been investigated, but results are
not consistent enough to validate shear modulus determination with this test method.
4.3 Iosipescu test
A test specimen with two centrally located V notches (see Figure 3) is submitted to a translation of its
part B parallel to the plies plane while its part A is kept still.
The displacement of part B with respect to part A results in an assumed uniform shear field in the
measurement zone.
Force and strain are measured and recorded simultaneously, from which shear modulus and shear
strength can be determined.
NOTE Before the failure, for high levels of shear stress, debonding of strain gauges often occurs.
Consequently, this test method is not suited to provide a valid shear-stress-shear-strain curve in the vicinity of
the interlaminar shear strength.
Schematics of the test pieces are shown in Figures 2 and 3.
Considering the orientation of the stack of plies with respect to the notches and the material orientation
definitions defined in ISO 19634, σ , and G (or G ) as well as σ , and G (or G ) can be
ILSS,13 13 1 ILSS,23 23 2
determined.
© I
...