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BS EN ISO 844:2021 pdf free

BS EN ISO 844:2021 pdf free.Rigid cellular plastics – Determination of compression properties.
This document specifies methods for determining the compressive strength and corresponding relative deformation, the compressive stress at 10 % relative deformation, and the compressive modulus of rigid cellular plastics.
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 291. Plastics — Standard atmospheres for conditioning and testing
ISO 1923. Cellular plastics and rubbers — Determination of linear dimensions
ISO 7500-1. Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and ver!fication of the force-measuring system
ISO 9513. Metallic materials — Calibration of extensometer systems used in uniaxial testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
5 Principle
A compressive force is applied in an axial direction and perpendicular to the faces of test specimen.
There are two procedures:
— Procedure A employs crosshead motion for determination of compressive properties. Procedure A shall be used to determine:
— compressive strength and the corresponding nominal relative deformation;
— compressive stress at 10 % nominal relative deformation;
— nominal compressive modulus.
— Procedure B employs strain measuring devices connected to the specimen contact or optical extensometer) or similar device which directly measures the specimen deformation. Procedure B shall be used to determine:
— compressive strength and the corresponding relative deformation:
— compressive modulus.
6 Apparatus
6.1 Compression-testing machine
Use a 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. The compression plates shall be of any convenient size which ensures that test specimens are compressed over their whole areas. The following conditions have been found acceptable:
a) surface roughness of Ra < 0,4 tm;
b) steel plate thickness oft  8 mm in the loading direction;
c) in case of thin samples, platens dimensions shall be so that clip on short travel extensometers with stop stud, can be appropriately clamped to the specimen when it is put in the centre of the platens.BS EN ISO 844 pdf free download.

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