NF EN ISO 178
Plastics - Determination of flexural properties
ISO 178:2010 specifies a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions. A standard test specimen is defined, but parameters are included for alternative specimen sizes for use where appropriate. A range of test speeds is included.The method is used to investigate the flexural behaviour of the test specimens and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship under the conditions defined. It applies to a freely supported beam, loaded at midspan (three-point loading test).The method is suitable for use with the following range of materials:thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in addition to unfilled types; rigid thermoplastics sheets;thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets.ISO 178:2010 applies to fibre-reinforced compounds with fibre lengths less than or equal to 7,5 mm prior to processing. For long-fibre-reinforced materials (laminates) with fibre lengths greater than 7,5 mm, see ISO 14125.The method is not normally suitable for use with rigid cellular materials or sandwich structures containing cellular material. In such cases, ISO 1209‑1 and/or ISO 1209‑2 can be used.Contrary to the previous editions of this International Standard, this edition specifies two methods, method A and method B. Method A is identical to the method in previous editions of this International Standard, i.e. it uses a strain rate of 1 %/min throughout the test. Method B uses two different strain rates: 1 %/min for the determination of the flexural modulus and 5 %/min or 50 %/min, depending on the ductility of the material, for the determination of the remainder of the flexural stress-strain curve.
ISO 178:2010 specifies a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions. A standard test specimen is defined, but parameters are included for alternative specimen sizes for use where appropriate. A range of test speeds is included.
The method is used to investigate the flexural behaviour of the test specimens and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship under the conditions defined. It applies to a freely supported beam, loaded at midspan (three-point loading test).
The method is suitable for use with the following range of materials:
- thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in addition to unfilled types; rigid thermoplastics sheets;
- thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets.
ISO 178:2010 applies to fibre-reinforced compounds with fibre lengths less than or equal to 7,5 mm prior to processing. For long-fibre-reinforced materials (laminates) with fibre lengths greater than 7,5 mm, see ISO 14125.
The method is not normally suitable for use with rigid cellular materials or sandwich structures containing cellular material. In such cases, ISO 1209‑1 and/or ISO 1209‑2 can be used.
Contrary to the previous editions of this International Standard, this edition specifies two methods, method A and method B. Method A is identical to the method in previous editions of this International Standard, i.e. it uses a strain rate of 1 %/min throughout the test. Method B uses two different strain rates: 1 %/min for the determination of the flexural modulus and 5 %/min or 50 %/min, depending on the ductility of the material, for the determination of the remainder of the flexural stress-strain curve.
Le présent document décrit une méthode pour déterminer des propriétés en flexion des plastiques rigides (voir 3.12) et semi-rigides dans des conditions définies.
Le présent amendement précise la fidélité de la détermination de propriétés de flexion.
This document specifies a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions. A preferred test specimen is defined, but parameters are included for alternative specimen sizes for use where appropriate. A range of test speeds is included. The method is used to investigate the flexural behaviour of the test specimens and to determine the flexural strength, flexural modulus and other aspects of the flexural stress/strain relationship under the conditions defined. It applies to a freely supported beam, loaded at midspan (three-point loading test). The method is suitable for use with the following range of materials: — thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in addition to unfilled types; rigid thermoplastics sheets; — thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets. In agreement with ISO 10350-1[5] and ISO 10350-2[6], this document applies to fibre-reinforced compounds with fibre lengths ≤7,5 mm prior to processing. For long-fibre-reinforced materials (laminates) with fibre lengths >7,5 mm, see ISO 14125[7]. The method is not normally suitable for use with rigid cellular materials or sandwich structures containing cellular material. In such cases, ISO 1209-1[3] and/or ISO 1209-2[4] can be used. NOTE 1 For certain types of textile-fibre-reinforced plastic, a four-point bending test is used. This is described in ISO 14125. The method is performed using specimens which can be either moulded to the specified dimensions, machined from the central section of a standard multipurpose test specimen (see ISO 20753) or machined from finished or semi-finished products, such as mouldings, laminates, or extruded or cast sheet. The method specifies the preferred dimensions for the test specimen. Tests which are carried out on specimens of different dimensions, or on specimens which are prepared under different conditions, can produce results which are not comparable. Other factors, such as the test speed and the conditioning of the specimens, can also influence the results. NOTE 2 Especially for injection moulded semi-crystalline polymers, the thickness of the oriented skin layer, which is dependent on the moulding conditions, also affects the flexural properties. The method is not suitable for the determination of design parameters but can be used in materials testing and as a quality control test.
- Avant-proposiv
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1 Domaine d'application1
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2 Références normatives2
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3 Termes et définitions3
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4 Principe5
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5 Machine d'essai5
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5.1 Généralités5
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5.2 Vitesse d'essai5
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5.3 Supports et poinçon de charge6
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5.4 Indicateurs de charge et de flèche6
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5.5 Dispositifs de mesurage de la largeur et de l'épaisseur des éprouvettes8
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6 Éprouvettes8
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6.1 Forme et dimensions8
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6.2 Matériaux anisotropes9
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6.3 Préparation des éprouvettes10
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6.4 Contrôle des éprouvettes11
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6.5 Nombre d'éprouvettes11
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7 Atmosphère de conditionnement et d'essai11
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8 Mode opératoire11
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9 Calcul et expression des résultats14
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9.1 Contrainte en flexion14
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9.2 Déformation en flexion15
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9.3 Module en flexion15
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9.4 Paramètres statistiques16
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9.5 Chiffres significatifs16
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10 Fidélité16
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11 Rapport d'essai16
- Annexe A (informative) Déclaration de fidélité17
- Annexe B (informative) Influence d'un changement de la vitesse d'essai sur les valeurs mesurées des propriétés en flexion19
- Bibliographie20
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