ISO 527-4:2023

Overview

ISO 527-4:2023 - "Plastics - Determination of tensile properties - Part 4" defines the test conditions for measuring tensile properties of isotropic and orthotropic fibre‑reinforced plastic composites. Based on the general principles of ISO 527-1, this third edition (2023) specifies how to prepare specimens, conduct tensile tests, and derive properties such as tensile strength, tensile modulus and Poisson’s ratios for a wide range of non‑unidirectional composites and symmetrical laminates. The standard adds a new type 4 tapered specimen geometry for testing without end tabs and provides updated guidance on gripping and grip‑face design.

Key topics and technical requirements

• Scope of materials: fibre‑reinforced thermosetting and thermoplastic composites with non‑unidirectional reinforcements (mats, woven fabrics, woven rovings, chopped strands, hybrids, short/milled fibres, prepregs) and finished products; typical fibres include glass, carbon, aramid.
• Test properties: determination of engineering stress–strain behaviour, ultimate tensile strength, tensile modulus (slope between specified strains), strain at strength, and Poisson’s ratio.
• Specimen types and preparation: dimensions, preparation methods, gauge marks, and anisotropy checks for established specimen types (including the new type 4 tapered specimen that enables testing without bonded end tabs).
• Gripping and tabs: procedures for clamping, use and application of end tabs (type 3), guidance for grip face design and unbonded or fine‑face gripping options.
• Test procedure and data: environmental conditioning, measurement of dimensions, setting extensometers/strain gauges, test speeds for different specimen types, data recording and calculation methods (including failure‑location related calculations for tapered specimens).
• Normative references: ISO 527-1 (general principles), ISO 527-2 (injection‑moulded specimens), ISO 527-5 (unidirectional materials), ISO 1268, ISO 2818, ISO 16012.

Applications and users

ISO 527-4:2023 is intended for:

• Materials and composites testing laboratories performing tensile characterization.
• Composite manufacturers (thermoset and thermoplastic) for quality control and material data generation.
• Design and R&D engineers requiring accurate tensile property data for structural analysis and laminate design.
• Certification bodies and procurement teams specifying material acceptance criteria. The standard is especially useful when testing multidirectional and symmetrical laminate composites, or when bonding end tabs is difficult (e.g., thermoplastic‑matrix systems).

Related standards

• ISO 527-1:2019 - General principles for tensile testing of plastics
• ISO 527-2 - Injection moulded specimens
• ISO 527-5 - Test conditions for unidirectional fibre‑reinforced plastics
• ISO 1268, ISO 2818, ISO 16012 - specimen production and dimensional measurement guidance

Keywords: ISO 527-4:2023, tensile properties, fibre-reinforced plastic composites, isotropic composites, orthotropic composites, tensile strength, tensile modulus, Poisson’s ratio, composite testing.