ISO 15733:2026

International
Standard
ISO 15733
Third edition
Fine ceramics (advanced ceramics,
2026-06
advanced technical ceramics) —
Mechanical properties of ceramic
composites at ambient temperature
in air atmospheric pressure —
Determination of tensile properties
Céramiques techniques — Propriétés mécaniques des céramiques
composites à température ambiante sous air à pression
atmosphérique — Détermination des propriétés en traction
Reference number
© ISO 2026
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Principle . 3
5 Apparatus . 4
5.1 Test machine .4
5.2 Load train .4
5.3 Extensometer .4
5.4 Data recording system .5
5.5 Micrometer .5
6 Test specimens . 5
7 Test specimen preparation . 8
7.1 Machining and preparation .8
7.2 Number of test of specimens .8
8 Test procedures . 8
8.1 Test set-up: other considerations .8
8.1.1 Displacement rate .8
8.1.2 Measurement of test specimen dimensions .8
8.2 Testing technique .8
8.2.1 Specimen mounting .8
8.2.2 Setting of extensometers .8
8.2.3 Measurements .9
8.3 Test validity .9
9 Calculation of results . 10
9.1 Test specimen origin .10
9.2 Tensile strength .10
9.3 Longitudinal Strain .10
9.4 Lateral strain .10
9.5 Longitudinal strain at maximum tensile force .11
9.6 Tensile modulus .11
9.7 Poisson’s ratio . 12
10 Test report .12
Annex A (informative) Illustration of tensile modulus . 14
Bibliography .15

iii
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
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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)
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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 third edition cancels and replaces the second edition (ISO 15733:2015), which has been technically
revised.
The main changes are as follows:
— broader range of tensile properties: tensile modulus, Poisson’s ratio, strength, fracture strain, lateral
deformations;
— test validity: possible singularities of force-deformation curves;
— editorial changes.
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.

iv
International Standard ISO 15733:2026(en)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Mechanical properties of ceramic composites
at ambient temperature in air atmospheric pressure —
Determination of tensile properties
1 Scope
This document specifies the conditions for determining the tensile properties (including tensile modulus,
Poisson’s ratio, strength, strain at maximum force and fracture strain) of ceramic matrix composite
materials with continuous fibre reinforcement at room temperature. This document applies to all ceramic
matrix composites with a continuous fibre reinforcement, including unidirectional (1D), bi-directional (2D),
and multi-directional (xD, with x > 2), reinforcement, loaded along a principal axis of reinforcement.
NOTE In most cases, ceramic matrix composites to be used at high temperature in air are coated with an
antioxidation coating.
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 — Design and
metrological characteristics of micrometers for external measurements
ISO 7500-1:2018, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ASTM E2208−02S–2018, Standard Guide for Evaluating Non-Contacting Optical Strain Measurement Systems
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions 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/
3.1
calibrated length
l
part of the test specimen that has uniform and minimum cross-section area
3.2
gauge length
L
o
initial distance between reference points on the test specimen in the calibrated length (3.1)

3.3
lateral gauge length
L
gauge length in direction perpendicular to the specific direction of loading
3.4
initial cross-section area
S
o
cross-section area of the test specimen within the calibrated length before loading
3.5
effective cross-section area
S
o,eff
total area corrected by a factor, to account for the presence of a coating
3.6
longitudinal deformation
A
increase in the gauge length parallel to the load direction under a tensile force
Note 1 to entry: Longitudinal deformation refers to axial deformation
3.7
lateral deformation
A
change of the lateral gauge length in a direction perpendicular to the specific direction of loading
3.8
longitudinal deformation at maximum tensile force
A
m
value of deformation corresponding to the maximum tensile force
3.9
tensile strain
ε
ratio of deformation to initial gauge length defined as the ratio of longitudinal deformation/gauge length (A/
L )
3.10
tensile strain at maximum force
ε
m
value of strain corresponding to the maximum tensile force
3.11
fracture strain
strain at ultimate fracture of the test specimen
3.12
lateral strain
ε
ratio of lateral deformation to initial lateral gauge length defined as the ratio of lateral deformation/lateral
gauge length (A /L )
2 02
3.13
tensile stress
σ
ratio of the force carried by the test piece to the initial cross-section area (S )
o
3.14
effective tensile stress
σ
eff
ratio of the force carried by the test piece to the effective cross-section area (S )
o,eff
3.15
maximum tensile force
F
m
maximum force during a test
3.16
tensile strength
σ
m
ratio of the maximum tensile force to the initial cross-section area (S )
o
3.17
effective tensile strength
σ
m,eff
ratio of the maximum tensile force to the effective cross-section area
3.18
tensile modulus
E
slope of the initial linear section of the stress-strain curve, at or near the origin
Note 1 to entry: The linear part could not exist or not start at the origin. The different situations are then described in
Annex A.
Note 2 to entry: Two tensile moduli depending of initial cross-section area can be defined as follows.
3.18.1
apparent tensile modulus
E
app
slope of the linear part of the stress-strain curve at or near the origin when the apparent tensile stress is
used
3.18.2
effective tensile modulus
E
eff
slope of the linear part of the stress-strain curve at or near the origin when the effective tensile stress is
used
3.19
Poisson’s ratio
ν
negative of the ratio of lateral strain to axial strain in an axially stressed body
4 Principle
A test specimen of specified dimensions is loaded in tension. The test is performed at constant crosshead
displacement rate, or constant deformation rate. Force and deformations are measured and recorded
simultaneously. Either longitudinal or both longitudinal and lateral deformations are measured.
NOTE The use of constant stress rate gives a valid tensile curve only when the material behaves linearly up to
failure.
5 Apparatus
5.1 Test machine
The test machine shall be equipped with a system for measuring the force applied to the test specimen
conforming to grade 1 or better according to ISO
...