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

General Information

Status
Withdrawn
Publication Date
09-Jun-2004
Withdrawal Date
09-Jun-2004
Current Stage
9599 - Withdrawal of International Standard
Start Date
04-Apr-2007
Completion Date
04-Apr-2007
Ref Project

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ISO 844:2004 - Rigid cellular plastics -- Determination of compression properties
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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
---------------------- Page: 1 ----------------------
ISO 844:2004(E)
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© ISO 2004

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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

© ISO 2004 – All rights reserved iii
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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
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

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
© ISO 2004 – All rights reserved 1
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ISO 844:2004(E)
3.2
compressive strength

maximum compressive force F divided by the initial cross-sectional area of the test specimen when the

relative deformation ε is < 10 %
3.3
compressive stress at 10 % relative deformation

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

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
E compressive modulus of elasticity, in kilopascals
F force corresponding to x (conventional proportional limit), in newtons
e e
F maximum force, in newtons
F force at 10 % relative deformation, in newtons
h initial thickness of test specimen, in millimetres
ε relative deformation ε corresponding to compressive strength σ , in percent
m m
σ compressive strength, in kilopascals
σ compressive stress at 10 % relative deformation, in kilopascals
x displacement at F in the conventional elastic zone, in millimetres
e e
x displacement at maximum force, in millimetres
x displacement at 10 % relative deformation, in millimetres
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”.
2 © ISO 2004 – All rights reserved
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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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