🔩 Determination of tensile strength, tensile modulus, Poisson’s ratios and the stress–strain relationship of thermosetting and thermoplastic composites reinforced with glass, carbon, aramid or similar fibres (mats, woven fabrics, rovings, chopped strands, prepregs, symmetrical multidirectional laminates) — according to the principles of ISO 527-1, specimens of type 1B, 2 (rectangular without end tabs), 3 (with bonded end tabs) or 4 (tapered without end tabs), thickness 2–10 mm, micrometer 0,01 mm, extensometer with 25 mm gauge length for type 4, PN-EN ISO 527-4

Materials and NDT PN-EN ISO 527-4

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN ISO 527-4:2023-10 (English version; scope in Polish on the card), in full (our translation of the Polish card text): “This document gives the conditions for determining the tensile properties of isotropic and orthotropic fibre-reinforced plastic composites based on the general principles given in ISO 527-1. NOTE 1 Unidirectionally reinforced materials are covered by ISO 527-5. The methods are used to investigate the tensile behaviour of specimens and to determine the tensile strength, modulus of elasticity, Poisson’s ratios and other properties resulting from the stress/strain relationship under defined conditions. The test method is suitable for use with the following materials: – thermosetting and thermoplastic composites reinforced with fibres, including non-unidirectional reinforcements such as mats, woven fabrics, woven rovings, chopped strands, combinations of such reinforcements, hybrids, rovings, short or milled fibres or pre-impregnated materials (prepregs); NOTE 2 Injection-moulded specimens are covered by ISO 527-2. – combinations of the above with unidirectional reinforcements and multidirectional ones made of unidirectional layers, provided such laminates are symmetrical; NOTE 3 Materials completely or mainly reinforced with unidirectional reinforcements are covered by ISO 527-5. – finished products made of these materials. Coated reinforcing fibres include glass, carbon, aramid and other similar fibres.” (The last sentence stands like this on the card; the ISO text says: the reinforcing fibres covered by the standard are glass, carbon, aramid and similar fibres.) We read the text of the standard in the preview of ISO 527-4:2023 from the cover to clause 6.1 (page 6); we do not have the specimen dimensions (Figures 3–5), preparation, number of specimens, test speed, calculations, the test report or Annexes A–E.

ACCORDING TO THE TEXT OF ISO 527-4:2023 (foreword, introduction, Clauses 1–6.1). The standard was prepared by ISO/TC 61/SC 13 (composites and reinforcement fibres) together with CEN/TC 249 (Vienna Agreement). The third edition replaces the second (2021) and is a minor revision: symbols in Figures 1 and 5, in Table B.2 and in Annex E were updated (upper case to lower case) and a bibliography item was added. Introduction: the document introduces a new specimen type — type 4, tapered, for use without end tabs, developed because of difficulties with bonding end tabs, especially with a thermoplastic matrix; guidance on gripping, including grip face design, was also added. Scope (Clause 1, as on the card). References: ISO 527-1:2019 (general principles), ISO 1268 (production of test plates), ISO 2818 (preparation of specimens by machining), ISO 16012 (measurement of dimensions). Definitions (Clause 3, according to ISO 527-1:2019): gauge length L0 (the values given in the parts of ISO 527 are the maximum relevant gauge length), thickness h and width b of the cross-section of the central part, test speed v (rate of separation of the grips), stress σ (σ1 for specimens in direction “1”, σ2 in direction “2”), strength σm, strain ε, strain at strength εm, modulus Et — slope of the σ(ε) curve in the interval ε1 = 0,05 % to ε2 = 0,25 % (as a chord modulus or the slope of a regression line; not applicable to films), Poisson’s ratio μ (positive), specimen axes 1, 2, 3 (direction “1” — 0° or longitudinal, associated with the material structure or process; “2” — 90°, transverse; “3” — through the thickness), failure position uF in the tapered part of a type 4 specimen. Principle (Clause 4): according to ISO 527-1. Apparatus (Clause 5): according to ISO 527-1:2019 Clause 5, with exceptions: micrometer (ISO 16012:2015, 5.5) reading to 0,01 mm or better, with a ball-ended anvil on irregular surfaces and a flat anvil on flat smooth (e.g. machined) ones; with type 4 specimens an extensometer with a gauge length of 25 mm (ISO 527-1:2019, 5.1.5); checking the alignment of the specimen and loading train according to Annex A is recommended. Specimens (6.1): four types — 1B (Figure 3), 2 and 3 (Figure 4), 4 (Figure 5); type 1B — for fibre-reinforced thermoplastics, also for thermosets if they break within the gauge length, but not for multidirectional continuous-fibre-reinforced materials; type 2 — rectangular without end tabs, type 3 — rectangular with bonded end tabs (specimens with unbonded tabs count as type 2), for thermosets and thermoplastics; preferred width of types 2 and 3 is 25 mm, and 50 mm or more when the strength is low because of the type of reinforcement; type 4 — tapered without end tabs, for fibre-reinforced composites, especially multidirectional continuous-fibre thermoplastics (Annex B); thickness of types 2, 3 and 4 — from 2 mm to 10 mm; testing starts without tabs (type 2 or 4), and if this is not successful — almost all specimens break in the grips — bonded end tabs are used (type 3); Annex C — unbonded tabs and gripping without tabs with fine grip faces at controlled gripping force; note: continuous-fibre composites have high breaking forces, and with a thickness of more than 4 mm a longer gripping length may be needed; recommended thickness for continuous-fibre composites — 2 mm; for compression-moulded materials the thickness between the end pieces must at no point deviate from the mean by more than 2 %; this is where the part we read ends.

STATUS (cards as of 02.10.2026). The card of PN-EN ISO 527-4:2023-10 (English version, published 05-10-2023, 42 pages, price group S) has no “Withdrawn” header: Chemistry Sector, KT 168 Plastic Products, ICS 83.120, “Introduces: EN ISO 527-4:2023 [IDT], ISO 527-4:2023 [IDT]”, “Replaces: PN-EN ISO 527-4:2022-06 – English version”. PN-EN ISO 527-4:2022-06 (English version, published 06-06-2022, 40 pages; introduced EN ISO 527-4:2021 and ISO 527-4:2021, replaced PN-EN ISO 527-4:2000) — “Withdrawal date: 05-10-2023”, replaced by PN-EN ISO 527-4:2023-10. The PKN search for “PN-EN ISO 527-4” (02.10.2026) also shows PN-EN ISO 527-4:2000 (Polish version).

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read on 02.10.2026). The number 527-4 appears in 8 records at 7 laboratories: AB 001, AB 005, AB 067, AB 154, AB 163, AB 1490, AB 1552. In the current scopes on the PCA website (read on 02.10.2026, issues from 17.12.2025 to 01.09.2026) the number appears at all 7: “PN-EN ISO 527-4:2023-10” at AB 001, AB 005, AB 067, AB 154 and AB 163 (two items: strength and modulus); AB 1552 lists the withdrawn “2022-06” next to “2023-10”; AB 1490 — without the year, next to ASTM D3039/D3039M and ASTM D5766/D5766M. Almost always in one cell with PN-EN ISO 527-1, -2, -3 and -5. No row is set in bold italics. The “Laboratories” tab searches for entries BEGINNING WITH “PN-EN ISO 527-4” and shows 5 laboratories (AB 001, AB 067, AB 154, AB 163, AB 1552); at AB 005 and AB 1490 the database entries begin with “PN-EN ISO 527-1”, so this tab does not show them — checked with a query of the tab on the production server labcoda.pl on 02.10.2026.

WHAT THE LABORATORIES TEST (items in the PCA scopes). Plastics and polymer composites, plastic and rubber products — at AB 154 explicitly “isotropic and orthotropic fibre-reinforced plastic composites (mats, woven fabrics, woven rovings, chopped…)”; properties — tensile strength, elongation at break, modulus of elasticity, yield point (AB 001, AB 005, AB 067, AB 154, AB 163), “Young’s modulus, Poisson’s ratio” in a temperature range from −55 °C to +149 °C and forces up to 200 kN (AB 1490), “tensile strength, nominal strain” (AB 1552); force ranges 100–400 kN.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. Part of the standard: materials completely or mainly unidirectional are tested according to ISO 527-5, injection mouldings — according to ISO 527-2; Part 4 concerns non-unidirectional reinforcements and symmetrical laminates. Specimen type: type 1B is not suitable for multidirectional continuous-fibre materials; when almost all specimens break in the grips, the test without tabs is regarded as unsuccessful and type 3 is used. Modulus: it is calculated in the narrow strain interval 0,05–0,25 % (chord or regression) — the method must be stated; for type 4 the extensometer gauge length is 25 mm. Direction: stresses σ1 and σ2 refer to directions “1” (0°) and “2” (90°) — the result for an orthotropic composite must be assigned to a direction. Dimensions: micrometer reading to 0,01 mm; the thickness of compression-moulded specimens must not deviate from the mean by more than 2 %. Edition: the 2023 edition differs from 2021 only in symbols and bibliography (AB 1552 lists both); the introduction of the standard presents the type 4 specimen and gripping guidance as new, so PN-EN ISO 527-4:2000 (Polish version), still visible in the PKN search, is not its equivalent.

WHAT WE DO NOT GIVE. We do not have the specimen dimensions (Figures 3–5), number of specimens, test speed, calculation method, the test report or Annexes A–E — so we do not give lengths, the width of the tapered part of type 4, tensile speeds or formulae.

Method principle

A composite specimen (type 1B, 2, 3 or 4) is stretched in a testing machine according to the principles of ISO 527-1, recording force and strain with an extensometer; strength, modulus (0,05–0,25 %) and Poisson’s ratios for the material directions are determined from the stress–strain curve.

Applications

• Polymer composites reinforced with glass, carbon and aramid fibres — 7 laboratories in the PCA scopes
• Laminates of mats, woven fabrics and prepregs, continuous-fibre thermoplastics (type 4 specimen)
• Finished composite products (specimens machined according to ISO 2818)

Key parameters

Standard

Standard number

PN-EN ISO 527-4:2023-10 (wersja angielska; EN ISO 527-4:2023 IDT, ISO 527-4:2023 IDT)

Title (PL)

Tworzywa sztuczne — Oznaczanie właściwości przy rozciąganiu — Część 4: Warunki badania kompozytów tworzywowych izotropowych i ortotropowych wzmocnionych włóknem

Title (EN)

Plastics — Determination of tensile properties — Part 4: Test conditions for isotropic and orthotropic fibre-reinforced plastic composites

Step-by-step procedure

1. Choice of specimen type

   Type 2 or 4 (without tabs); type 1B only for thermoplastics (not for multidirectional continuous fibre). PN-EN ISO 527-4:2023-10 current (cards as of 02.10.2026).

2. Preparation

   Plates according to ISO 1268, machining according to ISO 2818 in directions “1” and “2”; thickness 2–10 mm, measurement with a 0,01 mm micrometer.

3. Set-up

   Specimen aligned in the grips (check according to Annex A), extensometer (for type 4 gauge length 25 mm).

4. Tensile test

   According to ISO 527-1; if almost all specimens break in the grips — repetition on type 3 specimens with bonded end tabs.

5. Results

   Strength σm, strain εm, modulus Et (0,05–0,25 %), Poisson’s ratios μ — separately for the material directions; for type 4 the failure position uF.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• The part of the standard we read contains no safety warnings; continuous-fibre composites break violently at high forces — machine guards, goggles; dust from machining composites (glass, carbon fibres) — extraction and masks
• TECHNICAL NOTE: Part 4 does not cover unidirectional materials (ISO 527-5) or injection mouldings (ISO 527-2); the modulus is calculated in the interval 0,05–0,25 %

Frequently asked questions