ISO 5629:2017 紙と板—曲げ剛性の決定—共振法 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee SC 2, Test methods and quality specifications for paper and board.

This second edition cancels and replaces the first edition (ISO 5629:1983), of which it constitutes a minor revision.

The main changes compared with the previous edition are as follows:

• Annex B with precision data has been added;
• Bibliography has been added.

Introduction

There are many methods of measuring the resistance of paper and board to bending forces. Because of the visco-elastic nature of the material, results will depend to a considerable extent on the test method used. In this method, the bending stiffness is determined under dynamic conditions (vibration) using only a relatively small bending angle.

1 Scope

This document specifies a method for the determination of bending stiffness using the resonance method.

This method gives only a single result for each test piece tested, although in general, bending stiffness values may depend on which surface of the material forms the inner surface of the arc resulting from bending forces.

The bending stiffness of a very wide range of papers and boards can be measured using this method. However, for some materials, such as those listed below, the measured numerical values will not be strictly identical with bending stiffness as defined in 3.1:

• a) multi-ply papers and boards in which the component plies can move separately during a test;
• b) papers and boards with appreciable curl, especially if the axis of the curl is in the long direction of the test piece;
• c) some soft papers with grammage below about 40 g/m².

This method is not applicable to corrugated boards.

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.

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:

3.1

bending stiffness

S

moment of the resistance per unit width that a paper or board offers to bending in the region of elastic deformation. It can be defined mathematically by Formula (1):

(1)

where
	E	is the modulus of elasticity, i.e. Young's modulus;
	I	is the second moment of area (moment of inertia) of the cross-sectional area, about an axis through the centre of that area, in its plane, and perpendicular to the direction of bending;
	b	is the width of the test piece.

Bibliography