ISO 24046:2026

• Abstract:

  This document specifies a method for the determination of the tensile strength, tensile modulus of elasticity and strain at the maximum force of a resin-impregnated yarn specimen at ambient temperature. This method is applicable to yarns of ceramic fibres that are used as reinforcements in composite materials. The test results obtained by this method are applicable for quality control and comparison of the ceramic fibres. The outputs of this method are not comparable to the strength of filaments derived from tensile tests on dry tows specified in ISO 22459.

• Status: Published
• Publication Date: 02-Aug-2026
• ICS: 81.060.30 - Advanced ceramics
• Technical Committee: ISO/TC 206 - Fine ceramics
• Drafting Committee: ISO/TC 206/WG 4 - Composites
• Current Stage: 6060 - International Standard published
• Start Date: 03-Aug-2026
• Due Date: 03-Oct-2026
• Completion Date: 03-Aug-2026

• Revises: ISO 24046:2022 - Fine ceramics (advanced ceramics, advanced technical ceramics) — Methods of tests for reinforcements — Determination of the tensile properties of resin-impregnated yarns
• Effective Date: 05-Oct-2024

Overview

ISO 24046: Fine Ceramics - Test Methods for Tensile Properties of Resin-Impregnated Yarns specifies standardized procedures for determining the tensile strength, tensile modulus of elasticity, and strain at maximum force of resin-impregnated ceramic fibre yarns at ambient temperature. This method is crucial for assessing yarns used as reinforcements in ceramic matrix composites (CMCs), supporting consistent quality control and performance comparison of ceramic fibres in advanced technical and industrial applications.

Adherence to ISO 24046 ensures reliable, repeatable test conditions and helps manufacturers and users of fine ceramics maintain high standards in composite material production.

Key Topics

• Scope and Applicability

  • Measurement of tensile properties for resin-impregnated yarns made of ceramic fibres
  • Use in composite reinforcement applications
  • Ambient temperature testing conditions

• Test Apparatus and Materials

  • Use of suitable resin systems, including epoxy resins compatible with ceramic yarns
  • Requirements for impregnation apparatus, curing oven, tensile-testing machine, extensometer, high-precision balance, and ruler
  • Emphasis on precise measurement and uniform resin impregnation

• Specimen Preparation and Selection

  • Guidelines for minimum specimen numbers and selection based on uniformity and absence of defects
  • Procedures for resin impregnation and curing
  • Specification of acceptable resin content (30%–50% by mass)

• Testing Procedure

  • Conditioning specimens at standardized temperature and humidity
  • Clamping and testing at controlled cross-head speed, ensuring accuracy and avoidance of slippage or damage during mounting
  • Measurement of gauge length, longitudinal deformation, and application of force until failure

• Data Calculation and Reporting

  • Step-by-step calculation methods for tensile strength, modulus, and strain at maximum force
  • Correction for load train compliance when necessary
  • Statistical treatment of results and detailed reporting requirements

Applications

• Composite Material Development
  ISO 24046 is essential for manufacturers of ceramic matrix composites (CMCs) used in critical sectors such as:

  • Aerospace (jet engine and gas turbine components)
  • Power generation
  • Transportation and advanced engineering

• Quality Control and Supplier Comparison
  The standard provides a consistent approach to test and compare ceramic reinforcement fibres, enabling:

  • Reliable supplier benchmarking
  • Material certification for end-use applications
  • Verification of batch-to-batch consistency in manufacturing

• Research and Development
  Laboratories and R&D organizations use ISO 24046 for:

  • Development of new ceramic fibre types and resin systems
  • Optimization of composite reinforcements for high-performance and high-temperature applications

• Regulatory and Contractual Compliance
  Adhering to ISO 24046 helps companies:

  • Meet international regulatory standards
  • Fulfill contractual specifications for advanced ceramic components

Related Standards

• ISO 22459
  Used for testing the tensile properties of dry ceramic yarn tows, with results not directly comparable to those of resin-impregnated yarns as defined in ISO 24046.

• ISO 1889
  Standard for determining the linear density of reinforcement yarns.

• ISO 10119
  Used for determination of carbon fibre density, also applicable to ceramic fibre evaluation.

• ISO 10548
  Method for measuring the size content of carbon fibres, relevant for accurate calculations in resin-impregnated yarn testing.

Adopting ISO 24046 fosters international harmonization in the evaluation of fine ceramic reinforcements and supports advanced composites’ quality, reliability, and performance globally.

International
Standard
ISO 24046
Second edition
Fine ceramics (advanced ceramics,
2026-08
advanced technical ceramics) —
Methods of test for reinforcements
— Determination of the tensile
properties of resin-impregnated
yarns
Céramiques techniques — Méthodes d'essai pour renforts —
Détermination des propriétés en traction des fils imprégnés de
résine
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus and material . 3
5.1 Resin .3
5.2 Impregnation apparatus .3
5.3 Curing oven with temperature control .4
5.4 Tensile-testing machine and extensometer .4
5.4.1 Tensile-testing machine .4
5.4.2 Extensometer .4
5.5 Balance .4
5.6 Ruler .4
6 Test specimens . 4
6.1 Number of test specimens .4
6.2 Impregnation of test specimens .4
6.3 Determination of other fibre properties .5
6.3.1 General .5
6.3.2 Linear density of the yarn .5
6.3.3 Size content of the yarn .5
6.3.4 Density of the ceramic fibre .5
6.4 Criteria for selection of the test specimens .5
6.4.1 Specimens .5
6.4.2 Resin content of the specimens .5
6.4.3 Impregnated yarn .6
7 Atmospheres for conditioning and testing . 6
8 Procedure for tensile testing . 6
8.1 Procedure .6
8.2 Determination of load train compliance .6
8.3 Test validity .6
9 Calculation of results . 7
9.1 Tensile strength .7
9.2 Calculation of the load train compliance .7
9.3 Calculation of instantaneous total compliance and longitudinal deformation of resin-
impregnated yarn .8
9.4 Tensile modulus of elasticity .9
9.5 Tensile strain at maximum force (percentage elongation at failure) .10
9.5.1 Calculation method (1).10
9.5.2 Calculation method (2) .11
10 Statistics . .11
11 Test report .11
Annex A (informative) Examples of heat-curable epoxy-resin systems .13
Annex B (informative) Examples of resin-impregnating apparatus . 14
Annex C (informative) Example of extensometer .15
Bibliography . 17

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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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).
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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 24046:2022), which has been technically
revised.
The main changes are as follows:
— definitions 3.1, 3.2, 3.3, and 3.9 corrected;
— revision of 9.4 and 9.5 associated with the correction of terms and definitions.
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
Introduction
Fine ceramics are widely used in various fields, such as machinery, electronics, chemistry, construction,
energy, aerospace and the nuclear industry, and in environmental applications. Fibre-reinforced ceramic
matrix composites (CMCs) have been the subject of extensive research and development. CMCs are
lightweight, have suitable chemical and thermal stability, and exhibit high strength, elastic modulus and
creep resistance. These composites have been applied in devices and components in the aerospace industry
and in high-temperature applications.
CMCs have been put to practical use as components in the jet engines of passenger planes and are also being
developed as components of gas turbines for electric power generation.
The reliability of CMCs is influenced by the properties of the reinforcing fibre. High reliability is particularly
important for jet engine parts. The mechanical properties of these fibres also require fixed values and
distribution.
This document establishes a method for the measurement of mechanical properties such as tensile strength,
elastic modulus and strain at the maximum force of a resin-impregnated yarn specimen prepared from the
reinforcing ceramic fibre in CMCs.
Fibre and CMC manufacturers can use this method to perform quality control and relative comparison of
ceramic fibres used as the reinforcement of CMCs.

v
International Standard ISO 24046:2026(en)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Methods of test for reinforcements —
Determination of the tensile properties of resin-impregnated
yarns
1 Scope
This document specifies a method for the determination of the tensile strength, tensile modulus of elasticity
and strain at the maximum force of a resin-impregnated yarn specimen at ambient temperature. This
method is applicable to yarns of ceramic fibres that are used as reinforcements in composite materials. The
test results obtained by this method are applicable for quality control and comparison of the ceramic fibres.
The outputs of this method are not comparable to the strength of filaments derived from tensile tests on dry
tows specified in ISO 22459.
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 1889, Reinforcement yarns — Determination of linear density
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 10119, Carbon fibre — Determination of density
ISO 10548, Carbon fibre — Determination of size content
3 Terms and definitions
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
gauge length
L
initial distance between reference points on the test specimen in the calibrated length
[SOURCE: ISO 19634:2017, 4, Table 2.]
3.2
longitudinal deformation
A
variation in the gauge length (3.1) caused by an applied load
Note 1 to entry: Variation is positive in tensile and negative in compressive test.

[SOURCE: ISO 19634:2017, 4, Table 3.]
3.3
maximum tensile force
F
m
maximum force at fracture
[SOURCE: ISO 19634:2017, 4, Table 3, modified — The words “during a test or” have been removed from the
definition.]
3.4
tensile strength
σ
f
maximum tensile force (3.3) divided by the initial total cross-sectional area of the dry yarn (3.8)
[SOURCE: ISO 19630:2017, 3.6, modified —The words “of the dry yarn” have been added to make the
definition specific.]
3.5
total compliance
C
t
ratio of the measured displacement to the corresponding force during the tensile test
[SOURCE: ISO 22459:2024, 3.4.1]
3.6
load train compliance
C
l
ratio of the load train elongation, excluding the specimen contribution, to the corresponding force during
the tensile test
[SOURCE: ISO 22459:2024, 3.4.2]
3.7
tensile modulus of elasticity
E
f
slope of the force–deformation curve divided by the initial total cross-sectional area of the dry yarn (3.8)
3.8
initial total cross-sectional area of the dry yarn
S
f
linear density of the dry yarn (3.10) divided by the density of the dry yarn (3.12)
[SOURCE: ISO 22459:2024, 3.2, modified — The words “of the dry yarn” have been added to make the term
specific.]
3.9
tensile strain at maximum force
ε
t,m
value of strain corresponding to the maximumtensile force (3.3)
[SOURCE: ISO 19634:2017, 4, Table 3.]
3.10
linear density of the dry yarn
T
tf
mass of the dry yarn without a sizing agent divided by its length
[SOURCE: ISO 1889:2009, 3.1, modified — The words “of the dry yarn" have been added to the term and
defined as the value of dry yarn without a sizing agent, and Note 1 to entry has been removed.]

3.11
linear density of the impregnated yarn
T
ti
mass of the test specimen divided by its length
3.12
density of the dry yarn
ρ
f
mass of the dry yarn without a sizing agent divided by its volume
4 Principle
A fibre yarn impregnated with an epoxy resin is used as the specimen. A tensile force is applied to the
specimen at a constant displacement rate by a suitable mechanical testing machine and grip system
until failure. The longitudinal deformation of resin-impregnated yarn is measured directly by using an
extensometer or is determined from the displacement between two grips using a compliance correction.
The correction takes into account the contributions of the loading train, the grips and the tabbing materials.
The tensile strength, tensile modulus of elasticity and the strain at maximum force are calculated from the
force–deformation relationship. For ceramic fibre yarns in epoxy matrix, the relation between force and
longitudinal deformation is linear and, hence, the tensile modulus of elasticity is calculated from the slope of
the force–deformation curve.
5 Apparatus and material
5.1 Resin
The impregnating resin shall be compatible with the sizing agent and the type of yarn. The viscosity of the
resin or resin solution shall be such that sufficient resin pick-up and uniform impregnation are achieved.
The failure strain of the cured resin should be at least twice as large, preferably more than three times as
large, as that of the specimen. In this respect, thermosetting epoxy-resin systems are suitable (see Table A.1
for an example) as is any formulation capable of giving test specimens that fulfil the requirements of this
document.
5.2 Impregnation apparatus
Test speci
...