Overview
ISO 24281:2021 specifies a standardized test method to determine the maximum force and elongation at maximum force of woven textile fabrics using the grab method on a biaxial tensile (CRE) testing machine. The procedure is intended mainly for woven fabrics - including those with stretch from elastomeric fibres or mechanical/chemical treatments - and is restricted to constant-rate-of-extension (CRE) biaxial machines that apply loads simultaneously along warp and weft.
Key Topics and Technical Requirements
- Scope & exclusions: Applicable to woven fabrics; not applicable to geotextiles, nonwovens, coated fabrics, textile-glass woven fabrics, fabrics of carbon fibres or polyolefin tape yarns.
- Test principle: Square specimens are biaxially loaded in-plane with simultaneous warp/weft loading; maximum force and elongation at maximum force characterize biaxial tensile behavior.
- Specimen preparation & sampling:
- Cut at least five specimens per laboratory sample.
- Specimen size: 400 mm × 400 mm (±2 mm); avoid edges and selvedges (no specimens within 150 mm of sample edges).
- Mark lines 170 mm from one end for alignment of clamps.
- Apparatus requirements:
- CRE biaxial testing machine with four independently moving clamps and minimal system deflection.
- Force accuracy to class 1 (ISO 7500‑1); indicated maximum force error ≤ ±1%.
- Machine must set gauge length 200 mm (±1 mm) and rate of extension 50 mm/min (±10%).
- Clamping area for grab test: (50 mm ±1 mm) × (60 mm ±1 mm).
- Pretension & mounting:
- Pretension values specified by fabric type (e.g., 0.5 N for stretch fabrics; 2 N / 5 N / 10 N according to mass per unit area for non-stretch fabrics).
- Mount specimens aligned to marked warp/weft lines per Annex B.
- Test operation & reporting:
- Extend specimens to rupture, record maximum force (N) and elongation (%).
- Calculate averages of two readings per specimen and arithmetic mean across five specimens; rounding rules and resolution for elongation are specified.
- Report jaw breaks and follow rules for excluding or flagging abnormal clamp-zone failures.
- Conditioning: Preconditioning and test atmosphere per ISO 139; specimens recommended to be conditioned at least 24 h relaxed.
Applications and Users
ISO 24281:2021 is used by:
- Textile manufacturers and quality control labs assessing biaxial tensile performance of woven fabrics.
- Product developers evaluating fabric behavior under simultaneous warp/weft loads (e.g., apparel, technical textiles, stretch-treated fabrics).
- Test laboratories and certification bodies performing comparative or specification compliance tests.
Practical uses include fabric selection, performance benchmarking, quality acceptance testing, and informing design decisions where in‑plane biaxial strength and elongation influence product performance.
Related Standards
Keywords: ISO 24281:2021, biaxial tensile properties, woven fabric, grab method, maximum force, elongation at maximum force, CRE biaxial testing machine, textile testing.