SIST EN ISO 24370:2023

SLOVENSKI STANDARD
SIST EN ISO 24370:2023
01-maj-2023
Fina keramika (sodobna keramika, sodobna tehnična keramika) - Preskusne
metode za ugotavljanje odpornosti monolitske keramike proti lomljenju pri sobni
temperaturi z metodo upogibnega preskusa z zarezo (metoda CNB) (ISO
24370:2005)
Fine ceramics (advanced ceramics, advanced technical ceramics) - Test method for
fracture toughness of monolithic ceramics at room temperature by chevron-notched
beam (CNB) method (ISO 24370:2005)
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit
monolithischer Keramik an Biegeproben mit Chevron-Kerb (CNB-Verfahren) (ISO
24370:2005)
Céramiques techniques - Méthode d'essai de ténacité à la rupture des céramiques
monolithiques à température ambiante sur éprouvette entaillée en chevron (ISO
24370:2005)
Ta slovenski standard je istoveten z: EN ISO 24370:2023
ICS:
81.060.30 Sodobna keramika Advanced ceramics
SIST EN ISO 24370:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 24370:2023

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SIST EN ISO 24370:2023


EN ISO 24370
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2023
EUROPÄISCHE NORM
ICS 81.060.30 Supersedes EN 14425-3:2010
English Version

Fine ceramics (advanced ceramics, advanced technical
ceramics) - Test method for fracture toughness of
monolithic ceramics at room temperature by chevron-
notched beam (CNB) method (ISO 24370:2005)
Céramiques techniques - Méthode d'essai de ténacité à Hochleistungskeramik - Prüfverfahren zur
la rupture des céramiques monolithiques à Bestimmung der Bruchzähigkeit monolithischer
température ambiante sur éprouvette entaillée en Keramik an Biegeproben mit Chevron-Kerb (CNB-
chevron (ISO 24370:2005) Verfahren) (ISO 24370:2005)
This European Standard was approved by CEN on 10 March 2023.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 24370:2023 E
worldwide for CEN national Members.

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SIST EN ISO 24370:2023
EN ISO 24370:2023 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 24370:2023
EN ISO 24370:2023 (E)
European foreword
The text of ISO 24370:2005 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 24370:2023
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 September 2023, and conflicting national standards
shall be withdrawn at the latest by September 2023.
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 14425-3:2010.
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 24370:2005 has been approved by CEN as EN ISO 24370:2023 without any modification.

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SIST EN ISO 24370:2023

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SIST EN ISO 24370:2023


INTERNATIONAL ISO
STANDARD 24370
First edition
2005-06-01

Fine ceramics (advanced ceramics,
advanced technical ceramics) — Test
method for fracture toughness of
monolithic ceramics at room temperature
by chevron-notched beam (CNB) method
Céramiques techniques — Méthode d'essai de ténacité à la rupture des
céramiques monolithiques à température ambiante sur éprouvette
entaillée en chevron




Reference number
ISO 24370:2005(E)
©
ISO 2005

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SIST EN ISO 24370:2023
ISO 24370:2005(E)
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©  ISO 2005
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ii © ISO 2005 – All rights reserved

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SIST EN ISO 24370:2023
ISO 24370:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Symbols . 2
5 Principle . 3
6 Apparatus. 3
6.1 Test machine . 3
6.2 Flexure fixtures . 3
6.3 Micrometer. 4
6.4 Optical microscope. 4
6.5 Stability detection equipment. 5
7 Test specimens . 5
7.1 Geometry, size, preparation and edge chamfering . 5
7.2 Number of specimens. 8
8 Procedure. 9
8.1 Permitted test environments. 9
8.2 Test specimen dimensions and alignment. 9
8.3 Post-test measurements . 10
8.4 Post-test interpretation. 10
9 Calculation. 12
9.1 Calculations of the minimum stress intensity factor coefficient Y* . 12
min
9.2 Calculation of the fracture toughness value, K . 13
I,CNB
10 Test report. 13
Bibliography . 15

© ISO 2005 – All rights reserved iii

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SIST EN ISO 24370:2023
ISO 24370:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 24370 was prepared by Technical Committee ISO/TC 206, Fine ceramics.

iv © ISO 2005 – All rights reserved

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SIST EN ISO 24370:2023
INTERNATIONAL STANDARD ISO 24370:2005(E)

Fine ceramics (advanced ceramics, advanced technical
ceramics) — Test method for fracture toughness of monolithic
ceramics at room temperature by chevron-notched beam (CNB)
method
1 Scope
This International Standard specifies a test method for determining the fracture toughness of monolithic
ceramic materials at room temperature by the chevron-notched beam (CNB) method.
This International Standard is applicable to monolithic ceramics and whisker- or particulate-reinforced
ceramics that are regarded as macroscopically homogeneous. It is not applicable to continuous-fibre
reinforced ceramic composites.
This International Standard is usually applicable to ceramic materials with a fracture toughness less than
1/2
about 12 MPa(m ). The test method is applicable to materials with a flat crack-growth resistance curve and
may be applicable to materials with a rising crack-growth resistance curve (R-curve).
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.
ISO 7500-1:2004, Metallic materials — Verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Verification and calibration of the force-measuring system
ISO 14704:2000, Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for
flexural strength of monolithic ceramics at room temperature
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
stress intensity factor
K
I
magnitude of the elastic stress field singularity at the tip of a crack subjected to opening mode (mode I)
displacement
NOTE It is a function of applied force and test specimen size, geometry and crack length.
3.2
fracture toughness
generic term for measures of the resistance of extension of a crack
© ISO 2005 – All rights reserved 1

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SIST EN ISO 24370:2023
ISO 24370:2005(E)
3.3
fracture toughness value
K
I,CNB
value of crack-extension resistance, i.e. fracture toughness, as measured by the CNB method
NOTE The measured stress intensity factor corresponds to a crack-extension resistance of a stably-extending crack
in a chevron-notched beam specimen. The measurement is performed to the operational procedure herein and satisfies all
the validity requirements.
NOTE The definition, interpretation and measurement of K assume a flat crack-growth resistance curve.
I,CNB
3.4
critical stress intensity factor
K
Ic
critical value of K at which fracture occurs
I
4 Symbols
l chevron tip dimension, CNB method (Figure 2)
0
l chevron dimension, CNB method, [l = (l + l )/2]
1 1 11 12
l chevron dimension, CNB method (Figure 2)
11
l chevron dimension, CNB method (Figure 2)
12
B test specimen thickness (Figure 2)
K stress intensity factor, Mode I
I
K critical stress intensity factor, Mode I
Ic
K fracture toughness value, chevron-notched beam method
I,CNB
S flexure fixture outer span
o
S flexure fixture inner span
i
L test specimen length
F maximum force applied to the test specimen by the test machine and thereby recorded (Figure 5)
max
F force applied to the test specimen by the upper fixture
Tare
F total force applied to the test specimen (F + F ). This value is used in calculation of K
max Tare I,CNB
T notch thickness or kerf resulting from cutting of the chevron notch (Figure 2)
W test specimen width (Figure 2)
Y* minimum value of the stress intensity factor coefficient Y*
min
2 © ISO 2005 – All rights reserved

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SIST EN ISO 24370:2023
ISO 24370:2005(E)
5 Principle
This International Standard is intended to be used for material development, material comparison, quality
assurance, characterization, reliability analysis and design data generation. The chevron-notched beam
(CNB) method measures the fracture toughness value K by fracturing a flexural specimen, that has a
I,CNB
chevron notch (Figures 1 and 2). The specimen is fractured by four-point flexure. Force versus displacement,
and backface strain or time are recorded in order to detect unstable fracture. The fracture toughness value
K is calculated from the fracture load and the minimum stress intensity factor coefficient. Background
I,CNB
information concerning this test method may be found in References [1] and [2]. An international
interlaboratory comparison study (round robin) project on the chevron-notched method is described in
Reference [3], and a comparison of this method to other standardized methods is given in References [2] and
[4].
NOTE Ceramics generally exhibit stable crack extension from a chevron notch if the notch is sufficiently narrow
(< 0,30 mm), and the other notch dimensions are within the specified tolerances. If stable crack extension is not obtained,
then the fracture toughness cannot be directly measured.
6 Apparatus
6.1 Test machine
A suitable testing machine capable of applying a uniform cross-head speed shall be used. The testing
machine shall be in accordance with ISO 7500-1:2004 Class 1, with an accuracy of 1 % of the indicated force
at fracture.
6.2 Flexure fixtures
A schematic diagramme of a typical flexure fixture and test specimen is shown in Figure 1. Flexure fixtures
shall meet the requirements of ISO 14704. The fixtures should be semi-articulating. Test specimens shall be
contacted by smooth cylindrical bearings with a diameter between 4,50 mm and 5,00 mm. The diameter
should be uniform to ± 0,015 mm.
The bearings shall be free to roll in order to minimize friction, and the two inner bearings shall be free to roll
inward, and the two outer bearings shall be free to roll outward. The inner span, S, should measure
i
20 mm ± 0,5 mm and the outer span, S , should measure 40 mm ± 0,5 mm. Alternatively, the inner and outer
o
span may measure 10 mm and 30 mm, respectively.
When specific test environments other than the laboratory air are employed, an adequate chamber to hold the
environment around the test fixture is required. For gaseous environments such as dry nitrogen, a
polyethylene bag can be used. For liquid environments such as silicone oil or water, the specimen can be
coated and placed in the fixture or the fixture and test specimen can be immersed in a chamber containing the
liquid.
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SIST EN ISO 24370:2023
ISO 24370:2005(E)

Key
1 push rod
2 ball
3 test specimen
4 strain gauge
5 displacement transducer
6 support rod
7 flexure fixture inner span, S
i
8 flexure fixture outer span, S
o
Figure 1 — Schematic example of four-point flexure of a chevron-notched test specimen

6.3 Micrometer
[11]
A micrometer such as show
...