ISO 24281:2021

INTERNATIONAL ISO
STANDARD 24281
First edition
2021-07
Textiles — Biaxial tensile properties
of woven fabric — Determination of
maximum force and elongation at
maximum force using the grab method
Textile- Propriétés biaxiales des tissus- Détermination de la force
maximale et de l'élongation par la méthode d'arrachement
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Sampling . 3
6 Apparatus — Biaxial test machine . 4
7 Atmosphere for conditioning and testing . 4
8 Preparation of test specimens . 4
8.1 General . 4
8.2 Dimensions . 5
8.3 Preparation of test specimens . 5
9 Procedure. 5
9.1 Gauge length . 5
9.2 Rate of extension . 5
9.3 Mounting of test specimens . 5
9.4 Operation . 5
10 Calculation and expression of results . 6
11 Test report . 6
Annex A (informative) Locations of test specimens cut from a laboratory sample .8
Annex B (normative) Preparation of test specimens . 9
Bibliography .11
Foreword
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 38, Textiles, Subcommittee SC 24,
Conditioning atmospheres and physical tests for textile fabrics.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 24281:2021(E)
Textiles — Biaxial tensile properties of woven fabric
— Determination of maximum force and elongation at
maximum force using the grab method
1 Scope
This document specifies a procedure to determine the maximum force and elongation at maximum
force of textiles woven fabrics using a grab method in the biaxial testing machine.
The method is mainly applicable to woven textile fabrics, including fabrics which exhibit stretch
characteristics imparted by the presence of an elastomeric fibre, mechanical, or chemical treatment.
[4]
It can be applicable to fabrics produced by other techniques. It is not applicable to geotextiles ,
[3] [5] [2]
nonwovens , coated fabrics , textile-glass woven fabrics , and fabrics made from carbon fibres or
polyolefin tape yarns.
The method is restricted to the use of constant rate of extension (CRE) testing machines to the same
axis.
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 139, Textiles — Standard atmospheres for conditioning and testing
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 10012, Measurement management systems — Requirements for measurement processes and measuring
equipment
ISO 13934-1, Textiles — Tensile properties of fabrics — Part 1: Determination of maximum force and
elongation at maximum force using the strip method
ISO 13934-2, Textiles — Tensile properties of fabrics — Part 2: Determination of maximum force using the
grab method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13934-1, ISO 13934-2 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/
3.1
biaxial
related to measurement or application along two axes simultaneously
3.2
constant-rate-of-extension (CRE) biaxial testing machine
tensile-testing machine provided with four clamp moves independently with a constant speed
throughout the test, the entire testing system being virtually free from deflection
3.3
grab test
tensile test in which only the centre part of the test specimen is gripped in the jaws of the testing
machine
[SOURCE: ISO 13934-2:2014, 3.2]
3.4
maximum force
maximum force recorded when a test specimen is taken to rupture during a test under the specified
conditions
[SOURCE: ISO 13934-1:2013, 3.11]
3.5
gauge length
distance between the two effective clamping points of a testing device
Note 1 to entry: the effective clamping points (or lines) of jaws can be checked by clamping e test specimen under
defined pretension with carbon copy paper to produce a gripping pattern on the test specimen and/or the jaw
faces.
[SOURCE: ISO 13934-1:2013, 3.3]
3.6
extension
increase in length of a test specimen produced by a force
Note 1 to entry: Extension is expressed in units of length.
[SOURCE: ISO 13934-1:2013, 3.6]
3.7
elongation
ratio of the extension (3.6) of the test specimen to its initial length
Note 1 to entry: Elongation is expressed as a percentage.
[SOURCE: ISO 13934-1:2013, 3.7]
3.8
pretension
force applied to a test specimen at the beginning of certain tests
Note 1 to entry: Pretension is used to determine the initial length (3.9) of the test specimen.
[SOURCE: ISO 13934-1:2013, 3.5]
3.9
initial length
length of a test specimen under specified pretension (3.8) between the two effective clamping points at
the beginning of certain tests
Note 1 to entry: See also 3.5.
[SOURCE: ISO 13934-1:2013, 3.4]
2 © ISO 2021 – All rights reserved

3.10
elongation at maximum force
elongation (3.7) of a test specimen produced by the maximum force
Note 1 to entry: See Figure 1.
[SOURCE: ISO 13934-1:2013, 3.8]
Key
X elongation
Y force
a
Maximum force.
b
Force at rupture.
c
Pretension.
d
Elongation at max. force.
e
Elongation at rupture.
Figure 1 — Example of force-elongation curve
4 Principle
A test specimen of square shape is biaxially loaded in the plane of the fabric. The loads are applied
in the warp and weft directions simultaneously. Measurements of maximum force and elongation are
used to represent biaxial properties of the fabric.
5 Sampling
Select samples either in accordance with the procedure laid down in the material specification for the
fabric or as agreed between the interested parties.
In absence of an appropriate material specification, the example of suitable sampling procedure given
in Annex A may be used.
An example of a suitable pattern for cutting test specimens from the laboratory sample is given in
Annex A. Avoid test specimens with folded or creased areas, selvedges, and areas not representative of
the fabric.
6 Apparatus — Biaxial test machine
The testing apparatus shall be a constant-rate-of-extension (CRE) biaxial testing machine. Metrological
confirmation system of the biaxial testing machine shall be in accordance with ISO 10012.
The biaxial test machine shall be capable of simultaneously applying loads to the test specimen with
a specified load ration in the warp and weft directions. It shall be capable of measuring loads, strains
and/or displacements at suitable locations simultaneously.
The clamping or holding devices shall be capable of holding the test specimen without allowing it to slip
and designed so that they minimize damage to the test specimen.
6.1 The biaxial tensile testing machine shall be provided with means for indication or recording the
force applied to the test specimen in stretching it to rupture. Under conditions of use, the accuracy of the
apparatus shall be class 1 of ISO 7500-1. The error of the indicated or recorded maximum force at any
point in the range in which the machine is used shall not exceed ±1 % and the error of the indicated or
recorded jaw separation shall not exceed ±1 mm.
6.2 The machine shall be capable of a specified constant rate of extension with an accuracy of ±10 %.
6.3 The machine shall be capable of setting the specified gauge length with in ±1 mm.
6.
...