EN ISO 14129:1997

SLOVENSKI STANDARD
01-maj-1999
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Fibre-reinforced plastic composites - Determination of the in-plane shear stress/shear
strain response, including the in-plane shear modulus and strength, by the +/- 45°
tension test method (ISO 14129:1997)
Faserverstärkte Kunststoffe - Zugversuch an 45°-Laminaten zur Bestimmung der
Schubspannungs/Schubverformungs-Kurve, des Schubmoduls und der Schubfestigkeit
in der Lagenebene (ISO 14129:1997)
Composites plastiques renforcés de fibres - Détermination de la réponse contrainte-
déformation en cisaillement plan, module et résistance compris, par essai de traction a
+/- 45° (ISO 14129:1997)
Ta slovenski standard je istoveten z: EN ISO 14129:1997
ICS:
83.120 2MDþDQLSROLPHUL Reinforced plastics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 14129
First edition
1997-12-15
Fibre-reinforced plastic composites —
Determination of the in-plane shear stress/
shear strain response, including the
in-plane shear modulus and strength,
by the – 45� tension test method
Composites plastiques renforcés de fibres — Détermination de la réponse
contrainte-déformation en cisaillement plan, module et résistance compris,
par essai de traction à – 45�
A
Reference number
ISO 14129:1997(E)
ISO 14129:1997(E)
Contents Page
1 Scope . 1
2 Normative references . 1
3 Principle . 2
4 Definitions . 2
5 Apparatus . 2
6 Test specimens . 4
Number of test specimens .
7 4
8 Conditioning . 5
9 Procedure . 5
10 Calculation and expression of results . 6
11 Precision . 7
12 Test report . 7
Annex
A Specimen preparation . 8
©  ISO 1997
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
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microfilm, without permission in writing from the publisher.
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Printed in Switzerland
ii
©
ISO ISO 14129:1997(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.
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.
International Standard ISO 14129 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee SC 13, Composites and reinforcement
fibres.
Annex A forms an integral part of this International Standard.
iii
©
ISO 14129:1997(E) ISO
Introduction
This International Standard covers all current and future fibre-reinforced
plastic composites which fail in the required manner. Harmonisation with
the new tensile standard, ISO 527-5:1997, Plastics — Determination of
tensile properties — Part 5: Test conditions for unidirectional fibre-
reinforced plastic composites, has been achieved where relevant (e.g.
document format, specimen size and related strains for modulus
measurement).
The test is acceptable for modulus but there is concern over its use for the
ultimate shear strength for high shear-elongation materials due to the high
strain at failure with only a small further increase in load, fibre rotation and
associated temperature rise. Therefore, the stress at a maximum shear
strain of 5 % or less is used as the failure criterion. This failure criterion is
also used in ASTM D 3518 (1995).
iv
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INTERNATIONAL STANDARD  ISO ISO 14129:1997(E)
Fibre-reinforced plastic composites — Determination of the
in-plane shear stress/shear strain response, including the in-plane
shear modulus and strength, by the – 45� tension test method
1  Scope
1.1  This International Standard specifies a procedure for determining the in-plane shear stress/shear strain
response, including the in-plane shear modulus and shear strength, of fibre-reinforced plastic composites by the
– 45� tension test method.
1.2  The method is suitable for use with thermoset and thermoplastic matrix laminates made from unidirectional
layers and/or fabrics including unidirectional fabrics, with the fibres oriented at – 45� to the specimen axis, where the
lay-up is symmetrical and balanced about the specimen mid-plane.
NOTE —  The method is not suitable for coarse fabrics.
1.3  As the test has been shown to be sensitive to the number and distribution of layers, comparisons should be
undertaken using the same number of layers, which must be well distributed.
2  Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain
registers of currently valid International Standards.
ISO 291:1997, Plastics — Standard atmospheres for conditioning and testing.
ISO 1268:1974, Plastics — Preparation of glass fibre reinforced, resin bonded, low-pressure laminated plates or
1)
panels for test purposes.
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 5893:1993, Rubber and plastics test equipment — Tensile, flexural and compression types (constant rate of
traverse) — Description.
____________
1)  Under revision.
©
ISO
ISO 14129:1997(E)
3  Principle
A test specimen consisting of a strip of rectangular cross-section with the fibres oriented at – 45� to the specimen
axis is loaded in tension. To determine the shear modulus the strains parallel and perpendicular to the specimen
axis are measured. The test is terminated at g = 0,05 if failure (excluding premature failure at or within the grip)
has not occurred.
NOTE —  Although this test method can establish shear stress/shear strain response well into the nonlinear region, the
ultimate stress and strain values so obtained should be evaluated with the following caution. The material in the gauge section
of this specimen is not in a state of pure shear, as normal stress components are present, even in the rotated ply coordinate
system. It has been established that when a – 45� laminate is loaded in tension, normal stress components, though small,
generally decrease the calculated ultimate stress and strain values of the material below the actual capability of the material,
thus resulting in lower values of ultimate strength and strain than those obtained by more ideal methods, such as the tube
torsion test.
4  Definitions
For the purposes of this International Standard, the following definitions apply:
4.1  in-plane shear stress, t : The shear stress obtained by dividing the instantaneous load by twice the
specimen cross-sectional area.
It is expressed in megapascals (MPa).
4.2  in-plane shear strength, t : The maximum in the shear stress prior to or at termination of the test at
12M
g = 0,05.
It is expressed in megapascals (MPa).
4.3  shear strain, g : The sum total of strain in the direction parallel and perpendicular to the specimen axis, i.e.
(e - e ).
x y
NOTE —  e has an negative sign when e is positive.
y x
4.4  in-plane shear (chord) modulus, G : The shear stress difference (t ¢¢ - t ¢) divided by the corresponding
12 12 12
shear strain difference (g ¢¢ = 0,005 - g ¢ = 0,001) [see 10.3, equation (3)].
12 12
It is expressed in megapascals (MPa).
4.5  specimen coordinate axes: For the specimen shown in figure 1, the direction parallel to the specimen
longitudinal axis is the “x” direction and the direction perpendicular to it is the “y” direction. The fibres are oriented at
– 45� to these directions. The coordinate axes for a unidirectional reinforced composite material plate element are
shown in figure 2.
5  Apparatus
5.1  Test machine
5.1.1  General
The machine shall conform to ISO 5893 as appropriate to the requirements
...