EN ISO 21765:2021

Textiles - Determination of fabric deformability by forced mechanical distension (ISO 21765:2020)

This document specifies a method for the automatic determination of the deformability of textile fabrics, including continuous-fibre reinforcement textiles. This method is not applicable to resin impregnated fabrics.
The method is suitable for use with fabrics such as woven or knitted fabrics, nonwovens, non-crimp fabrics, fabrics made of glass rovings or untwisted carbon filament yarns intended for reinforced composite materials. When applying the method to multi-axial non-crimp fabrics, the evaluation of the fibre orientation and gaps only incorporates the uppermost layer.
The method can be used for fabrics treated with powder binder.

Textilien - Bestimmung der Verformbarkeit von Flächengebilden durch erzwungene Umformung (ISO 21765:2020)

Dieses Dokument legt ein Verfahren zur automatischen Bestimmung der Verformbarkeit von textilen Flächengebilden, einschließlich Verstärkungstextilien für endlosfaserverstärkte Textilien, fest. Dieses Verfahren ist nicht für harzimprägnierte Flächengebilde anzuwenden.
Das Verfahren ist geeignet für Flächengebilde wie Webstoffe oder Maschenware, Vliesstoffe, Gelege, Flächengebilde aus Glasrovings oder ungedrehten Kohlenstoff Filamentgarnen, die für verstärkte Werkstoff-Verbunde vorgesehen sind. Bei Anwendung des Verfahrens auf multiaxiale Gelege schließt die Auswertung der Faserorientierung und der Gaps nur die oberste Lage ein.
Das Verfahren kann für mit Pulverbinder behandelte Flächengebilde angewendet werden.

Textiles - Détermination de la déformabilité des étoffes par distension forcée mécaniquement (ISO 21765:2020)

Le présent document spécifie une méthode pour la détermination automatique de la déformabilité des étoffes textiles, y compris celle des textiles de renfort par fibres continues. Cette méthode n'est pas applicable aux étoffes imprégnées de résine.
La méthode est applicable aux étoffes telles que les étoffes tissées ou tricotées, les nontissés, les étoffes à base de fils sans embuvage, les étoffes constituées de mèches de verre ou les fils de filaments en carbone détordus destinés à des matériaux composites renforcés. Lors de l'application de la méthode à des étoffes à base de fils sans embuvage multiaxiales, l'évaluation de l'orientation des fibres et des espaces porte seulement sur la couche supérieure.
La méthode peut être utilisée pour des étoffes traitées avec un liant en poudre.

Tekstilije - Ugotavljanje deformabilnosti tkanine s prisilnim mehanskim raztezanjem (ISO 21765:2020)

General Information

• Status: Published
• Publication Date: 29-Apr-2021
• Withdrawal Date: 30-Jul-2021
• ICS: 59.080.30 - Textile fabrics
• Technical Committee: CEN/TC 248 - Textiles and textile products
• Drafting Committee: CEN/TC 248 - Textiles and textile products
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 13-Jan-2021
• Completion Date: 13-Jan-2021
• Ref Project: SIST EN ISO 21765:2021 - Textiles - Determination of fabric deformability by forced mechanical distension (ISO 21765:2020)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 21765:2021
01-marec-2021
Tekstilije - Ugotavljanje deformabilnosti tkanine s prisilnim mehanskim
raztezanjem (ISO 21765:2020)

Textiles - Determination of fabric deformability by forced mechanical distension (ISO

21765:2020)

Textilien - Automatische Bestimmung der Deformierbarkeit an Webstoffen und Gelegen

(ISO 21765:2020)
Textiles - Détermination de la déformabilité des étoffes par distension forcée
mécaniquement (ISO 21765:2020)
Ta slovenski standard je istoveten z: EN ISO 21765:2021
ICS:
59.060.01 Tekstilna vlakna na splošno Textile fibres in general
SIST EN ISO 21765:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 21765:2021
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SIST EN ISO 21765:2021
EN ISO 21765
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2021
EUROPÄISCHE NORM
ICS 59.080.30
English Version
Textiles - Determination of fabric deformability by forced
mechanical distension (ISO 21765:2020)

Textiles - Détermination de la déformabilité des étoffes Textilien - Automatische Bestimmung der

par distension forcée mécaniquement (ISO Deformierbarkeit an Webstoffen und Gelegen (ISO

21765:2020) 21765:2020)
This European Standard was approved by CEN on 7 December 2020.

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, Turkey 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

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21765:2021 E

worldwide for CEN national Members.
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SIST EN ISO 21765:2021
EN ISO 21765:2021 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

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SIST EN ISO 21765:2021
EN ISO 21765:2021 (E)
European foreword

This document (EN ISO 21765:2021) has been prepared by Technical Committee ISO/TC 38 "Textiles"

in collaboration with Technical Committee CEN/TC 248 “Textiles and textile products” the secretariat of

which is held by BSI.

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 July 2021, and conflicting national standards shall be

withdrawn at the latest by July 2021.

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.

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, Turkey and the

United Kingdom.
Endorsement notice

The text of ISO 21765:2020 has been approved by CEN as EN ISO 21765:2021 without any modification.

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SIST EN ISO 21765:2021
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SIST EN ISO 21765:2021
INTERNATIONAL ISO
STANDARD 21765
First edition
2020-12
Textiles — Determination of fabric
deformability by forced mechanical
distension
Textiles — Détermination de la déformabilité des étoffes par
distension forcée mécaniquement
Reference number
ISO 21765:2020(E)
ISO 2020
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SIST EN ISO 21765:2021
ISO 21765:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020

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]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
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SIST EN ISO 21765:2021
ISO 21765:2020(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 3

5 Apparatus ..................................................................................................................................................................................................................... 3

6 Test specimen .......................................................................................................................................................................................................... 5

7 Procedure..................................................................................................................................................................................................................... 6

7.1 Inserting the test specimen .......................................................................................................................................................... 6

7.2 Specifications of the test ................................................................................................................................................................. 6

7.2.1 Test parameters ................................................................................................................................................................ 6

7.2.2 Evaluation parameters................................................................................................................................................ 6

7.3 Test procedure ......................................................................................................................................................................................... 7

8 Calculation and specification of the results ............................................................................................................................. 7

8.1 Non-crimp fabric ................................................................................................................................................................................... 7

8.1.1 General...................................................................................................................................................................................... 7

8.1.2 Deformation force ........................................................................................................................................................... 8

8.1.3 Gap width ............................................................................................................................................................................... 8

8.1.4 Gap portion ........................................................................................................................................................................... 8

8.1.5 Gap shape ............................................................................................................................................................................... 8

8.1.6 Fibre-angle change ......................................................................................................................................................... 8

8.1.7 Undulation ............................................................................................................................................................................. 8

8.1.8 Loop formation .................................................................................................................................................................. 8

8.1.9 Waviness ................................................................................................................................................................................. 9

8.1.10 Out-of-roundness ............................................................................................................................................................ 9

8.2 Woven fabrics ........................................................................................................................................................................................... 9

8.2.1 Characteristic value names, symbols and units .................................................................................... 9

8.2.2 Deformation force ........................................................................................................................................................... 9

8.2.3 Gap portion ........................................................................................................................................................................... 9

8.2.4 Gap area ................................................................................................................................................................................10

8.2.5 Gap shape ............................................................................................................................................................................10

8.2.6 Fibre-angle change ......................................................................................................................................................10

8.2.7 Undulation ..........................................................................................................................................................................10

8.2.8 Shearing angle .................................................................................................................................................................10

8.2.9 Waviness ..............................................................................................................................................................................10

8.2.10 Out-of-roundness .........................................................................................................................................................10

8.2.11 Residual deformation ...............................................................................................................................................10

8.3 Knitted fabrics ......................................................................................................................................................................................11

8.3.1 Table with characteristic value names, symbols and units ......................................................11

8.3.2 Deformation force ........................................................................................................................................................11

8.3.3 Gap portion ........................................................................................................................................................................11

8.3.4 Gap area ................................................................................................................................................................................11

8.3.5 Gap shape ............................................................................................................................................................................11

8.3.6 Waviness ..............................................................................................................................................................................11

8.3.7 Out-of-roundness .........................................................................................................................................................11

8.3.8 Residual deformation ...............................................................................................................................................12

8.4 Nonwovens ..............................................................................................................................................................................................12

8.4.1 Table with characteristic value names, symbols and units ......................................................12

8.4.2 Deformation force ........................................................................................................................................................12

8.4.3 Anisotropy ..........................................................................................................................................................................12

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ISO 21765:2020(E)

8.4.4 Thinning-out .....................................................................................................................................................................12

8.4.5 Waviness ..............................................................................................................................................................................12

8.4.6 Out-of-roundness .........................................................................................................................................................13

8.4.7 Residual deformation ...............................................................................................................................................13

8.5 Evaluation .................................................................................................................................................................................................13

9 Test report ................................................................................................................................................................................................................13

Annex A (informative) Example images .........................................................................................................................................................16

Annex B (informative) Statistical data .............................................................................................................................................................18

Bibliography .............................................................................................................................................................................................................................19

iv © ISO 2020 – All rights reserved
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SIST EN ISO 21765:2021
ISO 21765:2020(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 38, Textiles, Subcommittee SC 24,

Conditioning atmospheres and physical tests for textile fabrics, in collaboration with the European

Committee for Standardization (CEN) Technical Committee CEN/TC 248, Textiles and textile products,

in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

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.
© ISO 2020 – All rights reserved v
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SIST EN ISO 21765:2021
ISO 21765:2020(E)
Introduction

The determination of the deformation characteristics is relevant for all production processes in which

flat textile fabrics (including reinforcement textiles) are formed into a three-dimensional shape. This

example is the case for upholstery applications or the majority of current liquid composite molding

(LCM) processes. Knowledge about the development of deformation effects such as changes in fibre

orientation, undulation, and gaps in the textile is crucial for the safe design of processes and components.

vi © ISO 2020 – All rights reserved
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SIST EN ISO 21765:2021
INTERNATIONAL STANDARD ISO 21765:2020(E)
Textiles — Determination of fabric deformability by forced
mechanical distension
1 Scope

This document specifies a method for the automatic determination of the deformability of textile fabrics,

including continuous-fibre reinforcement textiles. This method is not applicable to resin impregnated

fabrics.

The method is suitable for use with fabrics such as woven or knitted fabrics, nonwovens, non-crimp

fabrics, fabrics made of glass rovings or untwisted carbon filament yarns intended for reinforced

composite materials. When applying the method to multi-axial non-crimp fabrics, the evaluation of the

fibre orientation and gaps only incorporates the uppermost layer.
The method can be used for fabrics treated with powder binder.
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
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
reinforcement textile

fabric whose fibres are used to absorb and transfer the mechanical loads within a fibre-reinforced

composite material
3.2
deformability
conformability for forced three-dimensional deformation
3.3
specimen plane
plane which is defined by the inserted undeformed test specimen
3.4
specimen holder

device consisting of a retaining ring and a ring-shaped fitting body that retains the test specimen

during deformation with a settable, evenly distributed pressure
© ISO 2020 – All rights reserved 1
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SIST EN ISO 21765:2021
ISO 21765:2020(E)
3.5
deformation body

rotationally symmetrical body that deforms the test specimen centrally out of the specimen plane (3.3)

in a vertical upward direction
3.6
deformation level

level with specified height to which the deformation body (3.5) elevates out of the specimen plane (3.3)

3.7
deformation force

resulting force acting vertically on the deformation body (3.5) that arises during deformation

3.8
fibre orientation

orientation of the fibres or filaments of the test specimen, determined in the textile plane using image

processing
3.8.1
fibre-angle change
change of the global fibre orientation (3.8), determined using image processing
3.8.2
undulation
local change of the fibre orientation (3.8), determined using image processing
3.9
gap
open area between adjacent yarns, determined using image processing
EXAMPLE Non-crimp fabric gap, woven/knitted fabric gap.
3.10
waviness

continuous deformation over a certain region (>2 cm ) diverging from the textile plane, determined

using laser triangulation
3.11
loop formation

deformation of individual yarns out of the textile plane, determined using laser triangulation

3.12
out-of-roundness

deviation of the contour of the test specimen from a circular shape of equal area, determined using

image processing
3.13
overall image

image recorded with the overall image camera for determining the contour of the test specimen

3.14
detail image

image recorded by the detail camera with a minimum size of 1 000 mm and a minimum resolution of

64 pixels per millimetre
3.15
non-crimp fabric

fabric made of several unidirectional layers of straight multifilament yarns which are bonded using an

auxiliary stitching thread or chemical means

Note 1 to entry: The expression “non-crimp fabric” is commonly used in the composite sector.

2 © ISO 2020 – All rights reserved
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SIST EN ISO 21765:2021
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3.16
residual deformation

continuous deformation of the sample diverging from the support surface, determined using laser

triangulation, measured after completion of the deformation and return of the deformation body (3.5)

below the support surface
3.17
anisotropy
measure for the orientation of fibres in a nonwoven

Note 1 to entry: Values are between 1 (all fibres parallel to reference direction) and -1 (all fibres perpendicular to

reference direction), where 0 means complete isotropic (random) orientation
3.18
thinning-out

tendency of a nonwoven fabric to build local thin places due to mechanical stress

4 Principle

This document specifies a method by which the textile fabric (including reinforcement textiles) to be

examined is forced to be deformed in a defined manner by a rotationally symmetrical deformation

body. Key figures and characteristic values that describe the textile to be examined regarding its

deformability are determined. For this, the mechanical resistance to a defined three-dimensional

deformation is measured and the resulting structural faults in the mesostructure and macrostructure

are examined using a digital image analysis system and laser triangulation.

The test is carried out on a circular test specimen, which the testing instrument - by means of

a pneumatic specimen holder - holds in position with a defined force, which is equal around the

circumference of the retaining ring. During the test, the test specimen is incrementally deformed by a

deformation body acting from below and measured after each deformation level.

The force acting vertically on the deformation body caused by the deformation is measured.

Several images of the original undeformed test specimen and later of the deformed test specimen are

recorded with a detail camera on a central circular path and evaluated. For non-crimp fabrics, the fibre

orientation as well as the occurrence of gaps between the yarns of the non-crimp fabric are determined.

For woven fabrics, the angle between the warp threads and weft threads as well as the area and

proportion of the woven fabric gaps are determined. For knitted fabrics, the area and proportion of

the gaps is determined. For nonwovens, the anisotropy and thinning-out are determined. The out-of-

roundness of the test specimen is additionally determined with an overall image camera.

Additionally, deformations out of the textile plane may be recorded on the rotating test specimen using

a laser triangulation sensor and output as numerical values for the waviness and the loop formation.

5 Apparatus

5.1 Mechanical cutting equipment, to produce the circular test specimen from the laboratory sample.

NOTE Examples of suitable mechanical cutting equipment include punches and ultrasound cutters.

5.2 Deformability test apparatus

Test device in which the test specimen is inserted and uniformly retained over the entire circumference

using a specimen holder, whereby the retaining pressure can be specified in the range of 0 MPa to

0,1 MPa (i.e. 1 bar). The test device has a rotation device for motor-driven rotation of the test specimen

at variable speed [maximum speed (10,0 ± 0,1) min ], a motor-driven vertically moving deformation

body [elevation 0,00 – (100,00 ± 0,01) mm], a force sensor (0 N to 500 N with an accuracy of ±0,5 %)

to record the vertical force acting on the deformation body, an overall image camera to record the top

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ISO 21765:2020(E)

view of the entire test specimen, a detail camera to record detail images of the test specimen to detect

fine structural faults, as well as a laser triangulation sensor (sampling time shorter than 20 ms from

data acquisition to data storage) to record the deformations varying from the textile plane.

The deformation body features a spherical contact surface with a diameter of (100,0 ± 0,1) mm. This

deformation body can be black or white. The black deformation body is used to test light-coloured

materials and the white deformation body to test dark materials. The white deformation body can be

backlit.

The equipment for retaining the test specimen and for defined deformation is shown in Figure 1.

Key
1 test specimen
2 deformation body
3 support surface
4 retaining ring
5 fitting body
Figure 1 — Specimen holder and deformation body
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ISO 21765:2020(E)
Key
1 detail camera
2 laser triangulation sensor
3 overall image camera
Figure 2 — Schematic diagram of the optical sensors

Figure 2 illustrates the arrangement of the optical sensors. It shows a detail camera with lighting, an

overall image camera for recording the complete test specimen, as well a laser triangulation sensor to

record the test specimen topograph
...