SIST EN ISO 178:2003
(Main)Plastics - Determination of flexural properties (ISO 178:2001)
Plastics - Determination of flexural properties (ISO 178:2001)
Kunststoffe - Bestimmung der Biegeeigenschaften (ISO 178:2001)
1.1 Diese Internationale Norm legt ein Verfahren zur Ermittlung der Biegeeigenschaften von steifen (siehe 3.12) und halbsteifen Kunststoffen unter definierten Bedingungen fest. Es ist ein genormter Probekörper festgelegt, jedoch sind die Parameter für andere gegebenenfalls anzuwendende Probekörpergrößen enthalten. Ein Bereich von Prüfgeschwindigkeiten ist enthalten.
1.2 Das Verfahren wird für die Untersuchung des Biegeverhaltens [1] der Probekörper und für die Bestimmung der Biegefestigkeit, des Biegemoduls und anderer Gesichtspunkte der Spannungs-Dehnungs-Beziehung unter den definierten Bedingungen verwendet. Es wendet einen frei unterstützten Balken an, der in der Mitte der Auflagedistanz belastet wird (Dreipunktbiegeversuch).
1.3 Das Prüfverfahren ist zur Anwendung auf folgende Werkstoffgruppen geeignet:
thermoplastische Formmassen und Extrudiermassen, einschließlich gefüllter und verstärkter Formmassen in Ergänzung zu den ungefüllten Sorten; steife thermoplastische Platten;
duroplastische Formmassen, einschließlich gefüllter und verstärkter Compounds; duroplastische Platten.
In Übereinstimmung mit ISO 10350 1 und ISO 10350 2 gilt diese Internationale Norm für faserverstärkte Compounds mit Faserlängen von 7,5 mm vor der Verarbeitung. In Bezug auf Langfaser-verstärkte Werkstoffe (Laminate) mit Faserlängen von > 7,5 mm siehe Verweisung [2] in den Literaturhinweisen.
Das Verfahren ist üblicherweise nicht für harte Schaumstoffe und Schichtstoff-Verbundwerkstoffe geeignet, die Schaumstoffe enthalten [3], [4].
ANMERKUNG Für bestimmte Sorten Textilfaser-verstärkter Kunststoffe ist ein 4-Punkt-Biegeversuch vorzuziehen. Dieser ist in Verweisung [2] beschrieben.
1.4 Das Verfahren wird mit Probekörpern durchgeführt, die direkt in den festgelegten Maßen geformt, aus dem Mittelteil eines Norm-Vielzweckprobekörpers (siehe ISO 3167) ausgearbeitet oder aus fertigen oder halbfertigen Produkten wie Formteilen, Schichtstoffen und extrudierten oder gegossenen Platten a
Plastiques - Détermination des propriétés en flexion (ISO 178:2001)
Polimerni materiali - Določanje upogibnih lastnosti (ISO 178:2001)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 178:2003
01-julij-2003
1DGRPHãþD
SIST EN ISO 178:2000
3ROLPHUQLPDWHULDOL'RORþDQMHXSRJLEQLKODVWQRVWL ,62
Plastics - Determination of flexural properties (ISO 178:2001)
Kunststoffe - Bestimmung der Biegeeigenschaften (ISO 178:2001)
Plastiques - Détermination des propriétés en flexion (ISO 178:2001)
Ta slovenski standard je istoveten z: EN ISO 178:2003
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 178:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
EN ISO 178
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2003
ICS 83.080.01 Supersedes EN ISO 178:1996
English version
Plastics - Determination of flexural properties (ISO 178:2001)
Plastiques - Détermination des propriétés en flexion (ISO Kunststoffe - Bestimmung der Biegeeigenschaften (ISO
178:2001) 178:2001)
This European Standard was approved by CEN on 12 December 2002.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2003 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 178:2003 E
worldwide for CEN national Members.
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EN ISO 178:2003 (E)
CORRECTED 2003-03-26
Foreword
The text of ISO 178:2001 has been prepared by Technical Committee ISO/TC 61 "Plastics" of
the International Organization for Standardization (ISO) and has been taken over as EN ISO
178:2003 by Technical Committee CEN/TC 249 "Plastics", the secretariat of which is held by
IBN.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by August 2003, and conflicting national
standards shall be withdrawn at the latest by August 2003.
This document supersedes EN ISO 178:1996.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium, Czech
Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and
the United Kingdom.
Endorsement notice
The text of ISO 178:2001 has been approved by CEN as EN ISO 178:2003 without any
modifications.
NOTE Normative references to International Standards are listed in Annex ZA (normative).
2
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EN ISO 178:2003 (E)
Annex ZA
(normative)
Normative references to international publications
with their relevant European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of
any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified by common modifications, indicated
by (mod.), the relevant EN/HD applies.
Publication Year Title EN Year
ISO 291 1997 Plastics - Standard atmospheres for EN ISO 291 1997
conditioning and testing
ISO 294-1 1996 Plastics - Injection moulding of test EN ISO 294-1 1998
specimens of thermoplastic materials
- Part 1: General principles, and
moulding of multipurpose and bar test
specimens
ISO 295 1991 Plastics - Compression moulding of EN ISO 295 1998
test specimens of thermosetting
materials
ISO 2818 1994 Plastics - Preparation of test EN ISO 2818 1996
specimens by machining
ISO 3167 1993 Plastics - Multipurpose-test EN ISO 3167 1996
specimens
ISO 10724-1 1998 Plastics - Injection moulding of test EN ISO 10724-1 2001
specimens o f thermosetting powder
moulding compounds (PMCs) - Part
1: General principles and moulding of
multi purpose test specimens
3
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INTERNATIONAL ISO
STANDARD 178
Fourth edition
2001-12-15
Plastics — Determination of flexural
properties
Plastiques — Détermination des propriétés en flexion
Reference number
ISO 178:2001(E)
©
ISO 2001
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ISO 178:2001(E)
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ii © ISO 2001 – All rights reserved
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ISO 178:2001(E)
Contents Page
Foreword.iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 Principle.4
5 Test machine.5
6 Test specimens.6
7 Conditioning.9
8 Procedure.9
9 Calculation and expression of results.11
10 Precision.13
11 Test report.13
Annex A (normative) Compliance correction.14
Bibliography.15
© ISO 2001 – All rights reserved iii
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ISO 178:2001(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 178 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2,
Mechanical properties.
This fourth edition cancels and replaces the third edition (ISO 178:1993), which has been updated in the following
ways:
a method of correcting for curvature at the beginning of the stress/strain curve is given (see 9.2);
a method of correcting for the compliance of the test machine is given (see annex A).
Annex A forms a normative part of this International Standard.
iv © ISO 2001 – All rights reserved
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INTERNATIONAL STANDARD ISO 178:2001(E)
Plastics — Determination of flexural properties
1 Scope
1.1 This International Standard specifies a method for determining the flexural properties of rigid (see 3.12) 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.
[1]
1.2 The method is used to investigate the flexural behaviour of the test specimens and for determining 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).
1.3 The method is suitable for use with the following range of materials:
thermoplastics moulding and extrusion 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 and ISO 10350-2, this International Standard applies to fibre-reinforced
compounds with fibre lengths u 7,5 mm prior to processing. For long-fibre-reinforced materials (laminates) with
fibre lengths > 7,5 mm, see reference [2] in the bibliography.
The method is not normally suitable for use with rigid cellular materials and sandwich structures containing cellular
[3, 4]
material .
NOTE For certain types of textile-fibre-reinforced plastics, a four-point bending test is preferred. It is described in
reference [2].
1.4 The method is performed using specimens which may be moulded to the specified dimensions, machined
from the central portion of a standard multipurpose test specimen (see ISO 3167) or machined from finished or
semi-finished products such as mouldings, or extruded or cast sheet.
1.5 The method specifies 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, may produce results which
are not comparable. Other factors, such as the test speed and the conditioning of the specimens, can also
influence the results. Especially for semi-crystalline polymers, the thickness of the oriented skin layer, which is
dependent on moulding conditions and thickness, affects the flexural properties. Consequently, when comparable
data are required, these factors must be carefully controlled and recorded.
1.6 Flexural properties can only be used for engineering design purposes for materials with linear stress/strain
behaviour. For non-linear behaviour, the flexural properties are only nominal. The bending test should preferentially
be used with brittle materials, for which tensile tests are difficult.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
© ISO 2001 – All rights reserved 1
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ISO 178:2001(E)
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 291:1997, Plastics — Standard atmospheres for conditioning and testing
ISO 293:1986, Plastics — Compression moulding test specimens of thermoplastic materials
ISO 294-1:1996, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 1: General
principles, and moulding of multipurpose and bar specimens
1)
ISO 295:— , Plastics — Compression moulding of test specimens of thermosetting materials
ISO 2602:1980, Statistical interpretation of test results — Estimation of the mean — Confidence interval
ISO 2818:1994, Plastics — Preparation of test specimens by machining
ISO 3167:2001, Plastics — Multipurpose test specimens
ISO 5893:1993, Rubber and plastics test equipment — Tensile, flexural and compression types (constant rate of
traverse) — Description
ISO 10724-1:1998, Plastics — Injection moulding of test specimens of thermosetting powder moulding compounds
(PMCs) — Part 1: General principles and moulding of multipurpose test specimens
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
test speed
v
rate of relative movement between the supports and the loading edge
NOTE It is expressed in millimetres per minute (mm/min).
3.2
flexural stress
σ
f
nominal stress of the outer surface of the test specimen at midspan
NOTE It is calculated from the relationship given in 9.1, equation (5), and is expressed in megapascals (MPa).
3.3
flexural stress at break
σ
fB
flexural stress at break of the test specimen (see Figure 1, curves a and b)
NOTE It is expressed in megapascals (MPa).
3.4
flexural strength
σ
fM
maximum flexural stress sustained by the test specimen during a bending test (see Figure 1, curves a and b)
NOTE It is expressed in megapascals (MPa).
1) To be published. (Revision of ISO 295:1991)
2 © ISO 2001 – All rights reserved
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ISO 178:2001(E)
3.5
flexural stress at conventional deflection
σ
fc
flexural stress at the conventional deflection s defined in 3.7 (see Figure 1, curve c)
C
NOTE It is expressed in megapascals (MPa).
3.6
deflection
s
distance over which the top or bottom surface of the test specimen at midspan deviates from its original position
during flexure
NOTE It is expressed in millimetres (mm).
3.7
conventional deflection
s
C
deflection equal to 1,5 times the thickness h of the test specimen
NOTE 1 It is expressed in millimetres (mm).
NOTE 2 Using a span L of 16h, the conventional deflection corresponds to a flexural strain (see 3.8) of 3,5 %.
Curve a Specimen that breaks before yielding.
Curve b Specimen that gives a maximum and then breaks before the conventional deflection s .
C
Curve c Specimen that neither gives a maximum nor breaks before the conventional deflection s .
C
Figure 1 — Typical curves of flexural stress σ versus flexural strain ε and deflection s
f f
© ISO 2001 – All rights reserved 3
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ISO 178:2001(E)
3.8
flexural strain
ε
f
nominal fractional change in length of an element of the outer surface of the test specimen at midspan
NOTE 1 It is expressed as a dimensionless ratio or as a percentage (%).
NOTE 2 It is calculated in accordance with the relationships given in 9.2, equations (6) and (7).
3.9
flexural strain at break
ε
fB
flexural strain at break of the test specimen (see Figure 1, curves a and b)
NOTE It is expressed as a dimensionless ratio or as a percentage (%).
3.10
flexural strain at flexural strength
ε
fM
flexural strain at maximum flexural stress (see Figure 1, curves a and b)
NOTE It is expressed as a dimensionless ratio or as a percentage (%).
3.11
modulus of elasticity in flexure
flexural modulus
E
f
ratio of the stress difference σ − σ to the corresponding strain difference ε (= 0,002 5) − ε (= 0,000 5) [see
f2 f1 f2 f1
9.2, equation (9)]
NOTE 1 It is expressed in megapascals (MPa).
NOTE 2 The flexural modulus is only an approximate value of Young's modulus of elasticity.
NOTE 3 With computer-aided equipment, the determination of the modulus E using two distinct stress/strain points can be
f
replaced by a linear regression procedure applied to the part of the curve between these two points.
3.12
rigid plastic
a plastic that has a modulus of elasticity in flexure or, if that is not applicable, then in tension, greater than 700 MPa
under stated conditions [ISO 472]
4 Principle
The test specimen, supported as a beam, is deflected at a constant rate at the midspan until the specimen
fractures or until the de
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