SIST EN ISO 21971:2024

Fine ceramics (advanced ceramics, advanced technical ceramics) - Mechanical properties of ceramic composites at ambient temperature in air atmospheric pressure - Determination of hoop tensile properties of tubes (ISO 21971:2019)

This document specifies the conditions for the determination of hoop tensile properties of ceramic matrix composite (CMC) tubes with continuous fibre-reinforcement at ambient temperature in air atmospheric pressure. This document is specific to the tubular geometries since fibre architecture and specimen geometry factors in composite tubes are distinctly different from those in flat specimens.
This document provides information on the hoop tensile properties and stress-strain response, such as hoop tensile strength, hoop tensile strain at failure and elastic constants. The information can be used for material development, control of manufacturing (quality insurance), material comparison, characterization, reliability and design data generation for tubular components.
This document addresses, but is not restricted to, various suggested test piece fabrication methods. It applies primarily to ceramic and/or glass matrix composite tubes with a continuous fibrous-reinforcement: unidirectional (1D filament winding and tape lay-up), bi-directional (2D braid and weave) and tri-directional (xD, with 2 < x < 3), subjected to an internal pressure.
Values expressed in this document are in accordance with the International System of Units (SI).

Hochleistungskeramik - Zugfestigkeitseigenschaften von endlosfaserverstärkten keramischen Verbundrohren bei Umgebungstemperatur (ISO 21971:2019)

Céramiques techniques (céramiques avancées, céramiques techniques avancées) - Propriétés mécaniques des céramiques composites à température ambiante et à pression atmosphérique - Détermination des propriétés en traction circonférentielle de tubes (ISO 21971:2019)

Le présent document spécifie les conditions de détermination des propriétés en traction circonférentielle de tubes composites à matrice céramique (CMC) avec renfort de fibres continues à température ambiante et à pression atmosphérique. Il s'applique exclusivement aux tubulaire dont la géométrie est étroitement liée à la nature de l'architecture fibreuse.
Le présent document donne des informations sur le comportement en traction circonférentielle et sur les propriétés associées comme la résistance et la déformation en traction circonférentielle et les constantes élastiques. Les informations peuvent être utilisées pour le développement de matériaux, le contrôle de fabrication (assurance qualité), la comparaison de matériaux, la caractérisation ou encore pour la production de données fiables pour le dimensionnement et la conception de composants tubulaires.
Le présent document traite, sans s'y limiter, de pièces pouvant être élaborées par différentes voies. Il s'applique principalement aux tubes de céramique et/ou en verre matrice céramique avec renfort de fibres continues: unidirectionnel (enroulement filamentaire et disposition en bande 1D), bidirectionnel (tressage et tissage 2D), et tridirectionnel (xD, avec 2 < x < 3) soumis à une pression interne.
Les valeurs figurant dans le présent document sont exprimées selon le système international d'unités (SI).

Fina keramika (sodobna keramika, sodobna tehnična keramika) - Mehanske lastnosti keramičnih kompozitov pri temperaturi okolice in pri zračnem tlaku - Ugotavljanje nateznih lastnosti obroča cevi (ISO 21971:2019)

Ta dokument določa pogoje za ugotavljanje nateznih lastnosti obroča keramičnih matričnih kompozitnih (CMC) cevi z neprekinjeno ojačitvijo vlaken pri temperaturi okolice in zračnem tlaku. Dokument je namenjen predvsem za cevne geometrije, saj se arhitektura vlaken in
faktorji geometrije vzorca v kompozitnih ceveh bistveno razlikujejo od ravnih vzorcev.
Ta dokument vsebuje informacije o nateznih lastnostih obroča in odzivu napetost-deformacija, kot so natezna trdnost obroča, natezna napetost obroča pri okvari inelastične konstante. Informacije je mogoče uporabiti za razvoj materialov, nadzor proizvodnje (zagotavljanje kakovosti), primerjavo materialov, določanje lastnosti, zanesljivost in ustvarjanje podatkov o zasnovi za cevne komponente.
Ta dokument obravnava različne predlagane metode za izdelavo preskušanca, vendar ni omejen nanje.  Uporablja se predvsem za keramične in/ali steklene matrične kompozitne cevi z neprekinjeno ojačitvijo vlaken: enosmerno (1D navijanje filamentov in polaganje trakov), dvosmerno (2D vpletanje in tkanje) in trismerno (xD, kjer je 2 < x < 3), izpostavljene notranjemu tlaku.
Vrednosti, izražene v tem dokumentu, so v skladu z mednarodnim sistemom enot (SI).

General Information

• Status: Published
• Public Enquiry End Date: 30-Jul-2024
• Publication Date: 21-Oct-2024
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 15-Oct-2024
• Due Date: 20-Dec-2024
• Completion Date: 22-Oct-2024
• Ref Project: EN ISO 21971:2024 - Fine ceramics (advanced ceramics, advanced technical ceramics) - Mechanical properties of ceramic composites at ambient temperature in air atmospheric pressure - Determination of hoop tensile properties of tubes (ISO 21971:2019)

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2024
Fina keramika (sodobna keramika, sodobna tehnična keramika) - Mehanske
lastnosti keramičnih kompozitov pri temperaturi okolice in pri zračnem tlaku -
Ugotavljanje nateznih lastnosti obroča cevi (ISO 21971:2019)
Fine ceramics (advanced ceramics, advanced technical ceramics) - Mechanical
properties of ceramic composites at ambient temperature in air atmospheric pressure -
Determination of hoop tensile properties of tubes (ISO 21971:2019)
Hochleistungskeramik - Zugfestigkeitseigenschaften von endlosfaserverstärkten
keramischen Verbundrohren bei Umgebungstemperatur (ISO 21971:2019)
Céramiques techniques (céramiques avancées, céramiques techniques avancées) -
Propriétés mécaniques des céramiques composites à température ambiante et à
pression atmosphérique - Détermination des propriétés en traction circonférentielle de
tubes (ISO 21971:2019)
Ta slovenski standard je istoveten z: EN ISO 21971:2024
ICS:
81.060.30 Sodobna keramika Advanced ceramics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 21971
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2024
EUROPÄISCHE NORM
ICS 81.060.30
English Version
Fine ceramics (advanced ceramics, advanced technical
ceramics) - Mechanical properties of ceramic composites
at ambient temperature in air atmospheric pressure -
Determination of hoop tensile properties of tubes (ISO
21971:2019)
Céramiques techniques (céramiques avancées, Hochleistungskeramik - Mechanische Eigenschaften
céramiques techniques avancées) - Propriétés von keramischen Verbundwerkstoffen bei
mécaniques des céramiques composites à température Umgebungstemperatur und atmosphärischen
ambiante et à pression atmosphérique - Détermination Luftdruck - Bestimmung der Ringzugeigenschaften von
des propriétés en traction circonférentielle de tubes Rohren (ISO 21971:2019)
(ISO 21971:2019)
This European Standard was approved by CEN on 30 September 2024.

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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21971:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 21971:2019 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 21971:2024
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 April 2025, and conflicting national standards shall be
withdrawn at the latest by April 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.
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 21971:2019 has been approved by CEN as EN ISO 21971:2024 without any modification.

INTERNATIONAL ISO
STANDARD 21971
First edition
2019-12
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Mechanical properties of ceramic
composites at ambient temperature
in air atmospheric pressure —
Determination of hoop tensile
properties of tubes
Céramiques techniques (céramiques avancées, céramiques techniques
avancées) — Propriétés mécaniques des céramiques composites à
température ambiante et à pression atmosphérique — Détermination
des propriétés en traction circonférentielle de tubes
Reference number
ISO 21971:2019(E)
©
ISO 2019
ISO 21971:2019(E)
© ISO 2019
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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 21971:2019(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 4
5.1 Pressurizing system . 4
5.2 Test specimen gripping and end closure . 4
5.3 Strain measurement . 5
5.3.1 General. 5
5.3.2 Strain gauges . 5
5.3.3 Digital image correlation . 5
5.4 Pressure and data recording systems . 6
5.5 Measurement of dimensions . 6
6 Tubular test specimen . 7
6.1 Specimen specifications . 7
6.1.1 General. 7
6.1.2 Dimension . 7
6.1.3 Geometry . 7
6.1.4 Tolerances and variability . . 8
6.2 Specimen preparation . 8
6.2.1 General. 8
6.2.2 As-fabricated . 8
6.2.3 Application-matched machining . 9
6.2.4 Customary practices . 9
6.2.5 Standard procedure. 9
6.3 Test count and test specimens sampling . 9
7 Test procedure . 9
7.1 General . 9
7.2 Test mode and rates . 9
7.3 Testing technique .10
7.3.1 Measurement of test specimen dimensions .10
7.3.2 Instrumentation of test specimen .10
7.3.3 Setting-up of strain measurement means .10
7.3.4 Measurements .11
7.3.5 Post-test analyses .12
7.4 Test validity .12
8 Calculation of results .12
8.1 Test specimen origin .12
8.2 Hoop tensile stress and strain .12
8.3 Hoop tensile strength and corresponding strain.13
8.4 Proportionality ratio or pseudo-elastic modulus in circumferential direction.14
8.4.1 Stress-strain curves with a linear region .14
8.4.2 Nonlinear stress-strain curves .14
8.5 Poisson’s ratio (optional) .15
8.6 Statistics .15
9 Test report .15
9.1 General .15
9.2 Testing information.15
9.3 Test specimen and material .16
9.3.1 Tubular test specimen drawing or reference .16
ISO 21971:2019(E)
9.3.2 Description of the test material .16
9.4 Equipment and test parameters .16
9.5 Test results.16
Bibliography .18
iv © ISO 2019 – All rights reserved

ISO 21971:2019(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 documents 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).
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 rights. 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
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.
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.
INTERNATIONAL STANDARD ISO 21971:2019(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at ambient temperature in air atmospheric pressure —
Determination of hoop tensile properties of tubes
1 Scope
This document specifies the conditions for the determination of hoop tensile properties of ceramic
matrix composite (CMC) tubes with continuous fibre-reinforcement at ambient temperature in air
atmospheric pressure. This document is specific to the tubular geometries since fibre architecture and
specimen geometry factors in composite tubes are distinctly different from those in flat specimens.
This document provides information on the hoop tensile properties and stress-strain response, such
as hoop tensile strength, hoop tensile strain at failure and elastic constants. The information can be
used for material development, control of manufacturing (quality insurance), material comparison,
characterization, reliability and design data generation for tubular components.
This document addresses, but is not restricted to, various suggested test piece fabrication methods.
It applies primarily to ceramic and/or glass matrix composite tubes with a continuous fibrous-
reinforcement: unidirectional (1D filament winding and tape lay-up), bi-directional (2D braid and
weave) and tri-directional (xD, with 2 < x < 3), subjected to an internal pressure.
Values expressed in this document are in accordance with the International System of Units (SI).
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 20507, Fine ceramics (advanced ceramics, advanced technical ceramics) — Vocabulary
ASTM E2208-02, Standard Guide for Evaluating Non-Contacting Optical Strain Measurement Systems
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 20507 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
calibrated length
l
part of the test specimen that has uniform and minimum external diameter (3.3)
ISO 21971:2019(E)
3.2
gauge length
L
initial distance between reference points on the test specimen in the calibrated length (3.1)
3.3
external diameter
d
o
outer distance through the centre of the tube from one side to the other in the gauge length (3.2)
3.4
internal diameter
d
i
inner distance through the centre of the tube from one side to the other in the gauge length (3.2)
3.5
wall thickness
h
distance between the internal (3.4) and external diameters (3.3) in the gauge length (3.2)
3.6
hoop tensile strain
ε
θθ
relative change in circumferential direction in the gauge length (3.2)
3.7
axial strain
ε
zz
relative change in the axial (or longitudinal) direction in the gauge length (3.2)
3.8
hoop tensile stress
σ
θθ
stress supported by the test specimen in circumferential direction at any time in the test
3.9
burst pressure
P
F
highest recorded internal pressure undergone by the test specimen when tested to failure
3.10
hoop tensile strength
σ
θθ,m
hoop tensile stress (3.8) calculated at the burst pressure (3.9)
3.11
proportionality ratio or pseudo-elastic modulus in the circumferential direction
EP
θθ
slope of the initial linear section of the stress-strain curve
Note 1 to entry: Examination of the stress-strain curves for ceramic matrix composites allows definition in the
following cases:
a) Material with an initial linear domain in the stress-strain curve.

The proportionality ratio or pseudo-elastic modulus is termed the elastic modulus in the circumferential
direction, E , in the single case where the linearity starts near the origin.
θθ
b) Material with no-linear section in the stress-strain curve.

In this case only stress-strain couples can be fixed.
2 © ISO 2019 – All rights reserved

ISO 21971:2019(E)
3.12
Poisson’s ratio
ν
θz
negative ratio of circumferential to axial strain (3.7)
3.13
coordinate system
system used to determine location in space
Note 1 to entry: Cylindrical coordinates are adopted in this document.
Note 2 to entry: The notations shown in Figure 1 apply for space representation.
Key
z axial
r radial
θ circumferential
Figure 1 — Cylindrical coordinate system used for the CMC tubes
4 Principle
A prepared tubular test specimen of specified dimensions is inserted into an appropriate test fixture
assembly and subjected to monotonic loading via indirect internal pressure up to fracture. Uniform
radial pressure is produced using hydraulic oil injection with a piston through an elastomeric bladder
located inside the tubular test specimen. The elastomeric bladder mates to the inner diameter of the
tubular test specimen, thus causing its expansion under pressure. The test is performed at constant
piston displacement or constant strain (or constant loading rate). Both the applied pressure and
resulting hoop tensile strain are measured and recorded simultaneously. The hoop tensile strength
and corresponding strain are determined from the burst pressure while the various other hoop tensile
properties are determined from the stress-strain response data.
Generally, the test is carried out under conditions of ambient temperature and environment.
NOTE 1 The resulting force from internal pressure loading is applied in the radial direction. Monotonic refers
to a continuous non-stop test rate with no reversals from test initiation to final fracture.
NOTE 2 The method described in this document does not cover the possibility of applying pressurization via a
dense rubber material in compressive without fluid.
ISO 21971:2019(E)
5 Apparatus
5.1 Pressurizing system
The pressurizing system shall be able to apply a continuously increasing and uniform internal pressure
to the tubular test specimen.
The following equipment is recommended for this test:
a) an oil (or other fluid) bath maintained at uniform temperature;
b) an annular and leak-tight elastomeric bladder surrounding the inner periphery of the tubular test
specimen able to transmit a uniform pressure loading by its elasticity expansion;
c) a test machine (or a press) capable of applying a determined compressive force on a piston free to
move vertically to increase oil pressure in the elastomeric bladder.
Figure 2 shows a schematic example to illustrate the principle of a satisfactory pressurizing system.
Key
1 cover plate
2 tubular test specimen
3 elastomeric bladder
4 space flange
5 oil inlet for pressurization (P)
Figure 2 — Example of hydrostatic pressurizing system for CMC tubular test specimen
5.2 Test specimen gripping and end closure
The gripping device shall be able to maintain the tubular test specimen in position to withstand internal
pressure induced by the expansion of the elastomeric bladder while allowing it to move radially. An
example of construction detail is shown in Figure 2 for which the tubular test specimen is mounted on
a spacer flange. A cover plate is clamped on the flange with two screws to obtain a correct alignment.
The brittle nature of the CMCs requires particular attention to minimize crack initiation and fracture.
Therefore, it is recommended that the attachment screws are released and then the adjustment screw
adjusted to push the mating flanges back slightly until they come into contact with the tube, but without
applying any axial force to it.
4 © ISO 2019 – All rights reserved

ISO 21971:2019(E)
Specimen end closure shall be able to withstand the maximum test pressure. Closure shall be designed
so that it does not cause failure of the specimen.
5.3 Strain measurement
5.3.1 General
Strain should be locally measured in order to avoid having to take into account the compliance of the
machine. This may be by means of suitable bonded resistance strain gauges or digital image correlation
(DIC). If Poisson’s ratio is to be determined, the tubular test specimen shall be instrumented to measure
strain in both longitudinal and circumferential directi
...