ISO 21765-2020 PDF

Full title and description

St ISO 21765-2020 — Textiles — Determination of fabric deformability by forced mechanical distension. This international standard specifies an automated test method and apparatus for quantifying the deformability and related defects (gaps, undulation, wrinkles, fibre-angle change, etc.) of a wide range of textile fabrics, including woven, knitted, nonwovens and continuous-fibre reinforcement textiles (not applicable to resin‑impregnated fabrics).

Abstract

ISO 21765:2020 describes a method using mechanical distension combined with optical and laser-triangulation sensing to measure fabric deformation behaviour automatically. The method yields characteristic values such as deformation force, gap width/portion/shape, fibre-angle change, undulation, loop formation, waviness and out-of-roundness, and includes procedures and calculation rules for both non‑crimp and woven fabrics.

General information

• Status: Published (active).
• Publication date: December 2020.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 59.080.30 (Textile testing).
• Edition / version: Edition 1 (2020).
• Number of pages: 19 pages.

Details above are drawn from the ISO bibliographic entry for ISO 21765:2020.

Scope

ISO 21765:2020 specifies a test method for the automatic determination of fabric deformability by forced mechanical distension. It is suitable for woven fabrics, knitted fabrics, nonwovens, non‑crimp fabrics and fabrics made from continuous glass or carbon rovings/filaments used for reinforced composite materials. The method excludes resin‑impregnated fabrics. The standard defines specimen preparation (for example a circular specimen of specified diameter), apparatus configuration (deformation body, specimen holder, optical and laser sensors) and the sequence of measurements and evaluations.

Key topics and requirements

• Principle: forced mechanical distension of a circular specimen combined with optical imaging and laser triangulation to capture topography and defects.
• Apparatus: specimen holder, deformation body, retaining ring, optical cameras and laser triangulation sensor; detailed specifications and arrangements are provided.
• Specimen: defined geometry and preparation rules (e.g., circular specimen dimensions and edge‑cutting restrictions to avoid thermal damage).
• Test parameters: settings for force, displacement and imaging; procedures for inserting specimens and running automated tests.
• Evaluation parameters: deformation force, gap width/portion/shape, fibre‑angle change, undulation, loop formation, waviness, out‑of‑roundness; separate calculation rules for non‑crimp and woven fabrics.
• Reporting: specified characteristic value names, symbols and units for consistent reporting and comparison.
• Limitations: not applicable to resin‑impregnated (prepreg) materials; for multi‑axial non‑crimp fabrics the evaluation of fibre orientation and gaps may consider only the uppermost layer.

Key requirements and clause structure are summarized from the published standard and publicly available previews.

Typical use and users

Primary users are textile test laboratories, composite materials manufacturers, R&D groups, quality control departments and instrument manufacturers. The method is used to characterise drapability and deformability for product development, material selection (including recycled carbon-fibre nonwovens), process optimisation and incoming‑goods inspection. Specialized test houses and academic research groups working on textile reinforcements for composites will also apply ISO 21765 procedures.

Related standards

ISO 21765 complements other ISO and national textile and composite test methods (for example, series and individual standards covering nonwovens, textile physical testing and composite reinforcement characterisation produced under ISO/TC 38). Users commonly consult related textile testing standards and relevant ISO/TC 38 deliverables when integrating ISO 21765 into a test program.

Keywords

fabric deformability; drapability; forced mechanical distension; textile testing; non‑crimp fabrics; nonwovens; deformation force; gap measurement; laser triangulation; textile test method; ISO 21765:2020.

FAQ

Q: What is this standard?

A: ISO 21765:2020 is an international standard that specifies an automated laboratory method for determining the deformability and related defects of textile fabrics by forced mechanical distension.

Q: What does it cover?

A: It covers the principle, apparatus, specimen preparation, test procedure, evaluation parameters (e.g., deformation force, gap characteristics, fibre‑angle change, undulation, waviness) and calculation/reporting rules for a wide range of textile fabrics, excluding resin‑impregnated materials.

Q: Who typically uses it?

A: Textile testing laboratories, composite‑materials manufacturers, R&D teams, quality control groups, instrument makers and test houses that need standardised, comparable measurements of drapability and deformability. The method has been noted as useful for assessing nonwovens and recycled carbon‑fibre materials.

Q: Is it current or superseded?

A: ISO 21765 was published in December 2020 (first edition). As published by ISO it is active; ISO standards are subject to periodic review (typically every five years) and any change of status (confirmation, revision, withdrawal) would be recorded on the ISO bibliographic entry.

Q: Is it part of a series?

A: ISO 21765 is a standalone test method developed under ISO/TC 38 (Textiles), but it is complementary to other ISO textile testing standards and TC 38 deliverables; users often apply it alongside related textile and nonwoven test methods.

Q: What are the key keywords?

A: Deformability, drapability, forced mechanical distension, textile testing, laser triangulation, non‑crimp, nonwoven, deformation force, gap measurement.