ISO 844:2004
(Main)Rigid cellular plastics — Determination of compression properties
Rigid cellular plastics — Determination of compression properties
ISO 844:2004 specifies a method of determining a) the compressive strength and corresponding relative deformation or b) the compressive stress at 10 % relative deformation and c) when desired, the compressive modulus of rigid cellular plastics.
Plastiques alvéolaires rigides — Détermination des caractéristiques de compression
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 844
Fourth edition
2004-06-01
Rigid cellular plastics — Determination of
compression properties
Plastiques alvéolaires rigides — Détermination des caractéristiques de
compression
Reference number
ISO 844:2004(E)
©
ISO 2004
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ISO 844:2004(E)
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ii © ISO 2004 – All rights reserved
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ISO 844:2004(E)
Contents
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols and abbreviated terms.2
5 Principle .2
6 Apparatus.3
7 Test specimens .3
8 Procedure.4
9 Expression of results.4
10 Precision .7
11 Test report.7
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ISO 844:2004(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 844 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 10, Cellular plastics.
This fourth edition cancels and replaces the third edition (ISO 844:2001), which has been revised to include
precision data (see Clause 10).
iv © ISO 2004 – All rights reserved
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INTERNATIONAL STANDARD ISO 844:2004(E)
Rigid cellular plastics — Determination of compression
properties
1 Scope
This International Standard specifies a method of determining
a) the compressive strength and corresponding relative deformation
or
b) the compressive stress at 10 % relative deformation
and
c) when desired, the compressive modulus
of rigid cellular plastics.
2 Normative references
The following referenced documents are indispensable for the application 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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 1923, Cellular plastics and rubbers — Determination of linear dimensions
ISO 5725:1986, Precision of test methods — Determination of repeatability and reproducibility for a standard
test method by inter-laboratory tests
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
relative deformation
ε
ratio of the reduction (in relation to its initial value) in thickness of the test specimen to its initial thickness
NOTE 1 It is expressed as a percentage.
NOTE 2 ε is the relative deformation corresponding to σ (see 3.2).
m m
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ISO 844:2004(E)
3.2
compressive strength
σ
m
maximum compressive force F divided by the initial cross-sectional area of the test specimen when the
m
relative deformation ε is < 10 %
3.3
compressive stress at 10 % relative deformation
σ
10
ratio of the compressive force F at 10 % relative deformation ε to the initial cross-sectional area of the test
10 10
specimen
3.4
compressive modulus of elasticity
E
compressive stress divided by the corresponding relative deformation below the proportional limit, i.e. when
the relation is linear.
4 Symbols and abbreviated terms
A initial cross-sectional area, in square millimetres
0
E compressive modulus of elasticity, in kilopascals
F force corresponding to x (conventional proportional limit), in newtons
e e
F maximum force, in newtons
m
F force at 10 % relative deformation, in newtons
10
h initial thickness of test specimen, in millimetres
0
ε relative deformation ε corresponding to compressive strength σ , in percent
m m
σ compressive strength, in kilopascals
m
σ compressive stress at 10 % relative deformation, in kilopascals
10
x displacement at F in the conventional elastic zone, in millimetres
e e
x displacement at maximum force, in millimetres
m
x displacement at 10 % relative deformation, in millimetres
10
kPa kilopascals
Pa pascals
5 Principle
A compressive force is applied in an axial direction to the faces of a rectangular parallelepiped test specimen.
The maximum stress supported by the test specimen is calculated.
If the value of the maximum stress corresponds to a relative deformation of less than 10 %, it is noted as the
“compressive strength”. Otherwise, the compressive stress at 10 % relative deformation is calculated and its
value noted as the “compressive stress at 10 % relative deformation”.
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ISO 844:2004(E)
6 Apparatus
6.1 Compression-testing machine
Any compression-testing machine suited to the range of force and displacement involved and having two
square or circular plane, parallel plates which are polished and cannot be deformed and of which the length of
one side (or the diameter) is at least 10 cm. One of the plates shall be fixed and the other movable; the latter
shall be capable of moving at a constant rate of displacement in accordance with the conditions laid down in
Clause 8. Neither plate shall be self-aligning.
6.2 Devices for measuring displacement and force
6.2.1 Measurement of displacement
The compression-testing machine shall be fitted with a system allowing continuous measurement of the
displacement x of the movable plate with an accuracy of ± 5 % or ± 0,1 mm if this latter value is a more
accurate measurement (see Note to 6.2.2).
6.2.2 Measurement of force
A force sensor shall be fixed to one of the machine plates in order to measure the force F produced by the
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