oSIST prEN ISO 899-2 rev:2023

SLOVENSKI STANDARD
oSIST prEN ISO 899-2 rev:2023
01-april-2023
Nadomešča:
SIST EN ISO 899-2:2003/A1:2015
Polimerni materiali - Ugotavljanje lezenja - 2. del: Lezenje pri tritočkovni
obremenitvi (ISO/DIS 899-2:2023)
Plastics - Determination of creep behaviour - Part 2: Flexural creep by three-point
loading (ISO/DIS 899-2:2023)
Kunststoffe - Bestimmung des Kriechverhaltens - Teil 2: Zeitstand-Biegeversuch bei
Dreipunkt-Belastung (ISO/DIS 899‑2:2023)
Plastiques - Détermination du comportement au fluage - Partie 2: Fluage en flexion par
mise en charge en trois points (ISO/DIS 899-2:2023)
Ta slovenski standard je istoveten z: prEN ISO 899-2
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
oSIST prEN ISO 899-2 rev:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 899-2 rev:2023

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oSIST prEN ISO 899-2 rev:2023
DRAFT INTERNATIONAL STANDARD
ISO/DIS 899-2
ISO/TC 61/SC 2 Secretariat: SAC
Voting begins on: Voting terminates on:
2023-02-08 2023-05-03
Plastics — Determination of creep behaviour —
Part 2:
Flexural creep by three-point loading
Plastiques — Détermination du comportement au fluage —
Partie 2: Fluage en flexion par mise en charge en trois points
ICS: 83.080.01
IMPORTANT — Please use this updated version dated 2023-01-13, and discard any
previous version of this DIS. The link to figure 4 has been corrected.
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 899-2:2023(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2023

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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
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Published in Switzerland
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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Apparatus . 3
5 Test specimens . 5
6 Procedure .5
6.1 Conditioning and test atmosphere. 5
6.2 Measurement of test-specimen dimensions and distance between supports . 5
6.3 Mounting the test specimens . 5
6.4 Selection of stress value . 6
6.5 Loading procedure . 6
6.5.1 Preloading . 6
6.5.2 Loading . 6
6.6 Deflection-measurement schedule . 6
6.7 Time measurement . 6
6.8 Temperature and humidity control . 6
6.9 Measurement of recovery rate (optional) . 7
7 Expression of results . 7
7.1 Method of calculation . 7
7.1.1 Flexural-creep modulus . 7
7.1.2 Flexural-creep compliance . 7
7.1.3 Flexural stress . 7
7.1.4 Flexural-creep strain . 8
7.2 Presentation of results . 8
7.2.1 Creep curves. 8
7.2.2 Creep-modulus/time curves . 8
7.2.3 lsochronous stress-strain curves . 9
7.2.4 Three-dimensional representation . 10
7.2.5 Creep-to-rupture curves . 10
7.3 Precision . . . 10
8 Test report .10
Annex A (informative) Physical-ageing effects on the creep of polymers .12
Bibliography .16
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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(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 2.
The main task of technical committees is to prepare International Standards. 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 document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 899-2 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2, Mechanical
properties.
This third edition cancels and replaces the second edition (ISO 899-2:2015), which has been technically
revised.
ISO 899 consists of the following parts, under the general title Plastics — Determination of creep
behaviour:
— Part 1: Tensile creep
— Part 2: Flexural creep by three-point loading
The main changes are as follows:
— the accuracy requirements for the deflection measurement device were updated
— the text of ISO 899-2:2003/AMD 1:2015 has replaced the existing text in the Annex A.2
— the normative references were updated
— the definition of creep was adapted for more clearness
A list of all parts in the ISO 899 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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oSIST prEN ISO 899-2 rev:2023
DRAFT INTERNATIONAL STANDARD ISO/DIS 899-2:2023(E)
Plastics — Determination of creep behaviour —
Part 2:
Flexural creep by three-point loading
1 Scope
1.1 This part of ISO 899 specifies a method for determining the flexural creep of plastics in the form
of standard test specimens under specified conditions such as those of pre-treatment, temperature and
humidity. It applies only to a simple freely supported beam loaded at mid-span (three-point-loading
test).
1.2 The method is suitable for use with rigid and semi-rigid non-reinforced, filled and fibre-reinforced
plastics materials (see ISO 472 for definitions) test specimens moulded directly or machined from
sheets or moulded articles.
Note The method may be unsuitable for certain fibre-reinforced materials due to differences in fibre
orientation.
1.3 The method is intended to provide data for engineering-design, research and development
purposes. Data for engineering-design purposes requires the use of a deflectometer to measure the
deflection of the specimen.
1.4 The method may not be suitable for determining the flexural creep of rigid cellular plastics
(attention is drawn in this respect to ISO 1209-1, Cellular plastics, rigid — Flexural tests — Part 1:
Bending test, and ISO 1209-2, Cellular plastics, rigid — Flexural tests — Part 2: Determination of flexural
properties).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 62, Plastics — Determination of water absorption
ISO 178, Plastics — Determination of flexural properties
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 293, Plastics — Compression moulding of test specimens of thermoplastic materials
ISO 294-1, Plastics — Injection moulding of test specimens of thermoplastic materials — Part 1: General
principles, and moulding of multipurpose and bar test specimens
ISO 295, Plastics — Compression moulding of test specimens of thermosetting materials
ISO 2602, Statistical interpretation of test results — Estimation of the mean — Confidence interval
ISO 2818, Plastics — Preparation of test specimens by machining
ISO 472, Plastics — Vocabulary
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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(E)
ISO 9513, Metallic materials — Calibration of extensometer systems used in uniaxial testing
ISO 10724-1, Plastics — Injection moulding of test specimens of thermosetting powder moulding compounds
(PMCs) — Part 1: General principles and moulding of multipurpose test specimens
ISO 16012, Plastics — Determination of linear dimensions of test specimens
ISO 20753, Plastics — Test specimens
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
creep
increase in strain with time, measured from the first moment when the loading of the specimen started.
3.2
load
force applied to the test specimen at mid-span
Note 1 to entry: It is expressed in Newtons
3.3
flexural stress
σ
surface stress in the mid-span section of the test specimen
Note 1 to entry: It is expressed in megapascals.
Note 2 to entry: It is calculated from the relationship given in 7.1.3
3.4
deflection
s
t
distance over which the top or bottom surface of the test specimen at mid-span deviates from its
unloaded original position during flexure
Note 1 to entry: It is expressed in millimetres.
3.5
flexural-creep strain
ε
t
strain at the surface of the test specimen produced by a stress at any given time t during a creep test,
calculated in accordance with 7.1.4
Note 1 to entry: It is expressed as a dimensionless ratio or as a percentage.
3.6
flexural-creep modulus
E
t
ratio of flexural stress to flexural-creep strain, calculated as in 7.1.1
Note 1 to entry: It is expressed in megapascals.
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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(E)
3.7
flexural-creep compliance
Dt
ratio of flexural-creep strain to flexural stress, calculated as in 7.1.2
-1
Note 1 to entry: It is expressed in gigapascals
3.8
isochronous stress-strain curve
Cartesian plot of stress versus creep strain, at a specific time after application of the load to the
specimen
3.9
time to rupture
period of time the specimen is under full load until rupture
3.10
creep-strength limit
initial stress which will just cause rupture (σ ) or will produce a specified strain (σ ) at a specified
B,t ε,t
time t, at a given temperature and relative humidity
Note 1 to entry: It is expressed in millimetres
3.11
initial distance between specimen supports
span
L
initial distance between lines of contact between test specimen and supports (see Figure 1)
Note 1 to entry: It is expressed in millimetres
4 Apparatus
4.1 Test rack, comprising a rigid frame with two supports, one for each end of the test specimen, the
distance between the supports being adjustable to (16 ± 1) times the thickness (height) of the specimen
(see Figure 1) for normal specimens, or to greater than 17 times the thickness (height) of the specimen
or a fixed distance (100 mm) for rigid unidirectional-fibre-reinforced test specimens (see 6.2). The test
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oSIST prEN ISO 899-2 rev:2023
ISO/DIS 899-2:2023(E)
rack shall be levelled, and sufficient space shall be allowed below the specimen for the specimen to flex
under constant loading at mid-span.
Key
1 applied force, F L distance between supports
2 loading edge l specimen length
3 test specimen h specimen thickness
4 support R radius of the loading edge
1
R radius of the supports
2
Figure 1 — Characteristics of flexural-creep apparatus
The radius R of the loading edge and the radius R of the supports shall conform to the values given in
1 2
Table 1.
Table 1 — Radii of the loading edge and the supports
Values in millimetres
Radius of loading edge Radius of supports
Thickness of test spec-
imen
R R
1 2
≤ 3 5 ± 0,1 2 ± 0,2
> 3 5 ± 0,1 5 ± 0,2
4.2 Loading system, capable of ensuring that the load is applied smoothly, without causing
transient overloading, and that the load is maintained to within ±1 % of the desired load. In creep-to-
rupture tests, provision shall be made to prevent any shocks which occur at the moment of rupture
being transmitted to adjacent loading systems. The loading mechanism shall allow rapid, smooth and
reproducible loading.
4.3 Deflection-measuring device, comprising any contactless or contact device capable of
measuring the deflecti
...