ISO 4604:2011

Reinforcement fabrics - Determination of conventional flexural stiffness - Fixed-angle flexometer method

ISO 4604:2011 specifies a method of determining the conventional flexural stiffness of reinforcement fabrics by means of a fixed-angle flexometer. This method is not suitable for testing fabrics that are limp or that have a marked tendency to curl or twist or fray.

Tissus de renforcement — Détermination de la rigidité conventionnelle en flexion — Méthode du flexomètre à angle fixe

General Information

• Status: Published
• Publication Date: 20-Nov-2011
• ICS: 59.100.10 - Textile glass materials
• Technical Committee: ISO/TC 61/SC 13 - Composites and reinforcement fibres
• Drafting Committee: ISO/TC 61/SC 13/WG 1 - Reinforcements and reinforcement products
• Current Stage: 9093 - International Standard confirmed
• Start Date: 05-Oct-2021
• Completion Date: 13-Dec-2025

Relations

• Consolidated By: ISO 20344:2021 - Personal protective equipment - Test methods for footwear
• Effective Date: 06-Jun-2022
• Revises: ISO 4604:1978 - Textile glass - Woven fabrics - Determination of conventional flexural stiffness - Fixed angle flexometer method
• Effective Date: 12-Feb-2011

Overview

ISO 4604:2011 - Reinforcement fabrics - Determination of conventional flexural stiffness - Fixed-angle flexometer method specifies a laboratory procedure for measuring the conventional flexural stiffness of reinforcement fabrics (e.g., fabrics used in composites) using a fixed-angle flexometer. The method determines the overhanging length of a fabric strip bent under its own weight and converts that measurement, together with mass per unit area, into stiffness values. The procedure is not suitable for limp fabrics or fabrics with a marked tendency to curl, twist or fray.

Key topics and requirements

• Test principle: A rectangular strip is moved over a platform until its tip aligns with sighting lines inclined at 41.5° below the horizontal; the overhanging length is measured and used to compute stiffness.
• Specimen dimensions and quantities: Cut strips 25 mm × 250 mm; test six warp and six weft specimens (three per face orientation as specified).
• Apparatus: Fixed-angle flexometer with a slide 25 mm wide and at least 300 mm long; slide mass specified as 10 g ± 2 g per centimetre of length. Cutting die and suitable cutting device are required.
• Conditioning and atmosphere: Condition specimens per ISO 291 for at least 6 hours until mass is stable to 0.25% (reweighed at 2 h intervals); test in the same atmosphere.
• Calculation and units: Conventional flexural stiffness is calculated from the average overhanging length and the fabric’s mass per unit area (ρ determined per ISO 3374). Results are reported in millinewton metres (mN·m); ρ is in g/m² and length in metres.
• Reporting: Test report must reference ISO 4604:2011, identify the fabric and test conditions (conditioning temperature/humidity per ISO 291), give warp/weft stiffness per face, and note any deviations or incidents.

Applications and users

• Useful for quality control, comparative testing and specification of reinforcement fabrics used in composite part manufacture, structural textiles and technical fabrics.
• Typical users:
  • Textile and composite manufacturers assessing stiffness properties in warp and weft directions
  • Materials test laboratories and certification bodies
  • R&D teams developing reinforcement fabrics and process engineers selecting fabrics for molding or lay-up
  • Procurement/specification writers who need standardized stiffness data for material selection
• Practical value: Provides reproducible, comparable stiffness data to inform handling, drapability and processing behavior of reinforcement fabrics in manufacturing.

Related standards

• ISO 291 - Plastics - Standard atmospheres for conditioning and testing (conditioning requirements referenced)
• ISO 3374 - Reinforcement products - Mats and fabrics - Determination of mass per unit area (ρ measurement referenced)
• Prepared by ISO/TC 61 (Plastics), Subcommittee SC 13 (Composites and reinforcement fibres)

Keywords: ISO 4604:2011, reinforcement fabrics, flexural stiffness, fixed-angle flexometer, fabric testing, warp weft stiffness, ISO 291, ISO 3374.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 4604
Second edition
2011-11-15
Reinforcement fabrics — Determination
of conventional flexural stiffness —
Fixed-angle flexometer method
Tissus de renforcement — Détermination de la rigidité conventionnelle
en flexion — Méthode du flexomètre à angle fixe
Reference number
©
ISO 2011
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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 4604 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 13, Composites and
reinforcement fibres.
This second edition cancels and replaces the first edition (ISO 4604:1978), of which it constitutes a minor
revision. The main changes are as follows:
— the scope has been broadened to cover all reinforcement fabrics (not just textile glass fabrics) and the title
of the standard modified in consequence;
— the normative references clause has been updated.
INTERNATIONAL STANDARD ISO 4604:2011(E)
Reinforcement fabrics — Determination of conventional flexural
stiffness — Fixed-angle flexometer method
1 Scope
This International Standard specifies a method of determining the conventional flexural stiffness of reinforcement
fabrics by means of a fixed-angle flexometer. This method is not suitable for testing fabrics that are limp or that
have a marked tendency to curl or twist or fray.
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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 3374, Reinforcement products — Mats and fabrics — Determination of mass per unit area
3 Principle
A rectangular strip of fabric is supported on a horizontal platform in a direction perpendicular to one edge of
the platform. The strip is moved in the direction of its length so that an increasing portion overhangs and bends
down under its own weight. When the tip of the specimen has reached a plane passing through the edge of the
platform and inclined at an angle of 41,5° below the horizontal, the overhanging length is measured.
The conventional flexural stiffness is calculated from the overhanging length of the test specimen and the mass
per unit area of the fabric.
NOTE This determination of the conventional flexural stiffness is based on a report published in Shirley lnstitute
Memoirs, 9 (1930), p. 81, and Journal of the Textile lnstitute, 21 (1930), T380.
4 Apparatus
4.1 Fixed-angle flexometer, the essential features of which are shown in Figure 1.
On the horizontal platform P rests a slide S, graduated on its upper surface in millimetres.
The under-surface of S is covered with a layer of high-friction antistatic material such as sheet rubber, and the
upper surface of P is polished so that, when S is moved, it will carry forward a specimen placed between the
slide and the platform P.
The width of the slide S shall be 25 mm and the length at least 300 mm, and its mass shall be 10 g ± 2 g per
centimetre of length.
When the front edge of the slide coincides with the front edge of P, the zero of the scale on S coincides with
a datum line D on the ins
...