1、 ISO 2013 Paper and board Determination of fracture toughness Constant rate of elongation method (1,7 mm/s) Papier et carton Dtermination de la rsistance la rupture Mthode gradient dallongement constant (1,7 mm/s) TECHNICAL SPECIFICATION ISO/TS 17958 First edition 2013-04-15 Reference number ISO/TS
2、17958:2013(E) ISO/TS 17958:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
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4、l copyrightiso.org Web www.iso.org Published in Switzerland ISO/TS 17958:2013(E) ISO 2013 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Principle 3 5 Apparatus . 3 6 Calibration and adjustment of apparatus 5 7 Sam
5、pling and preparation of test pieces . 5 7.1 Sampling . 5 7.2 Conditioning 5 7.3 Determination of grammage . 6 7.4 Preparation of test pieces for tensile testing 6 7.5 Preparation of test pieces for fracture toughness testing 6 8 Procedure. 6 8.1 Tensile testing 6 8.2 Fracture toughness testing . 6
6、9 Calculations 7 9.1 General . 7 9.2 Tensile testing and evaluation of tensile properties . 7 9.3 Fracture toughness testing and evaluation of fracture toughness . 8 9.4 Determination of ISO fracture strength and ISO fracture strain 9 9.5 Indexed parameters .11 10 Report .11 Annex A (normative) Unce
7、rtainty determination .13 Bibliography .16 ISO/TS 17958:2013(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 co
8、mmittees. 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 th
9、e International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for
10、the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2. www.iso.org/directives Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO s
11、hall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received. www.iso.org/patents Any trade name used in this document is i
12、nformation given for the convenience of users and does not constitute an endorsement. The committee responsible for this document is ISO/TC 6, Paper, board and pulps, Subcommittee SC 2, Test methods and quality specifications for paper and board.iv ISO 2013 All rights reserved ISO/TS 17958:2013(E) I
13、ntroduction The essence of fracture mechanics theory is that the material parameter fracture toughness is determined by controlled laboratory testing before it is used to predict the fracture properties of structures or structural components containing defects. This Technical Specification describes
14、 a laboratory test method for determination of the fracture toughness of paper materials and a numerical method to predict the fracture strength and fracture strain of notched paper webs for a given reference paper web geometry called ISO paper web geometry. The specified methods are based on nonlin
15、ear fracture mechanics theory (J-integral theory). 1 23 The experimental procedure for determining the fracture toughness of this Technical Specification consists of two material tests: tensile testing and fracture toughness testing. Both these tests are performed following ISO 1924-3, with the exce
16、ption that 50 mm wide test pieces containing 20 mm- wide centre notches are used in the fracture toughness test. For material ranking and material development purposes, it is advantageous to define a notched reference geometry for predictions of fracture strength (stress at break) and fracture strai
17、n (strain at break). Such notched reference geometry makes it easier to compare fracture properties of different paper materials and to communicate results in reports and articles. The main application of fracture mechanics to paper materials is related to breaks in continuous web handling operation
18、s, such as in manufacture, winding, and printing. The characteristic dimensions of paper webs in such operations generally are in the order of metres, while defects in the paper webs commonly have a characteristic size in the order of millimetres. Furthermore, the most severe defects from a web brea
19、k perspective are located in the region of the edges of the paper web. In this Technical Specification, a 2 m long and 1 m wide paper web, containing a 10 mm edge notch, is used as the notched ISO paper web geometry for predicting and ranking of the fracture properties of paper materials. The terms
20、ISO fracture strength and ISO fracture strain are used to indicate that the fracture properties are determined for this particular notched ISO paper web geometry following this Technical Specification. A successful experimental validation of the procedure for determining the fracture properties for
21、the assigned ISO web geometry has been performed. 1 2 3 NOTE 1 The determined fracture toughness may also be utilized to predict fracture properties of paper webs and paper products that have different dimensions and shapes than the introduced ISO paper web geometry. The procedure for such predictio
22、ns is given in References 1, 2, and 3. NOTE 2 The fracture toughness alone does not constitute sufficient information to determine the fracture behaviour of structures or structural components. Consider the stress/strain curves for two materials, A and B, obtained by tensile testing of notched test
23、pieces (see Figure 1). The exemplified materials have equal fracture toughness but different fracture strengths and fracture strains. Materials A and B, which have different stress/strain behaviours, could for instance originate from machine direction (MD) and cross-machine direction (CD) of a parti
24、cular paper grade or could be two papers of different origin. Clearly, materials A and B are expected to behave very differently in converting operations, although they have equal fracture toughness. This example illustrates that the fracture toughness cannot be used to rank the fracture properties
25、of papers that show different stress/strain behaviour. However, the ISO fracture strength and ISO fracture strain, according to this Technical Specification, can be used to accurately rank the fracture properties of materials A and B. ISO 2013 All rights reserved v ISO/TS 17958:2013(E) Figure 1 Stre
26、ss/strain curves for two materials, A and B, obtained by tensile testing of notched test piecesvi ISO 2013 All rights reserved TECHNICAL SPECIFICATION ISO/TS 17958:2013(E) Paper and board Determination of fracture toughness Constant rate of elongation method (1,7 mm/s) 1 Scope This Technical Specifi
27、cation describes a method for determining the fracture toughness of paper and board using a tensile testing machine operated with a constant rate of elongation. This Technical Specification also describes the determination of the fracture strength and fracture strain of a notched paper web with an a
28、ssigned standard web geometry. This information is used to rank the fracture properties of paper materials. This Technical Specification is applicable to all kinds of paper and paperboard, except for certain special grades, such as creped paper and other paper materials that significantly deviate fr
29、om exhibiting monotonically decreasing tangential stiffness during tensile testing. This Technical Specification does not apply to corrugated fibreboard. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its app
30、lication. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 186, Paper and board Sampling to determine average quality ISO 187, Paper, board and pulps Standard atmosphere for conditionin
31、g and testing and procedure for monitoring the atmosphere and conditioning of samples ISO 536, Paper and board Determination of grammage ISO 1924-3, Paper and board Determination of tensile properties Part 3: Constant rate of elongation method (100 mm/min) 3 T erms a nd definiti ons For the purposes
32、 of this document, the following terms and definitions apply. 3.1 tensile stiffness E b maximum slope of the curve obtained when tensile force per unit width is plotted versus strain SOURCE: ISO 1924-3:2005, definition 3.8 3.2 tensile strength T b maximum tensile force per unit width that paper and
33、board will withstand before breaking under the conditions defined in this Technical Specification SOURCE: ISO 1924-3:2005, definition 3.1 ISO 2013 All rights reserved 1 ISO/TS 17958:2013(E) 3.3 tensile energy absorption T amount of energy per unit surface area (test length width) of a test piece whe
34、n it is strained to the maximum tensile force SOURCE: ISO 1924-3:2005, definition 3.6 3.4 strain at break T strain at the maximum tensile force SOURCE: ISO 1924-3:2005, definition 3.5 3.5 strain-hardening exponent N mathematically determined exponent describing the non-linear part of the stress/stra
35、in curve of the test material Note 1 to entry: The strainhardening exponent is dimensionless. 3.6 strain-hardening modulus 0 mathematically determined modulus describing the non-linear part of the stress/strain curve of the test material Note 1 to entry: The strainhardening modulus is expressed in n
36、ewtons per metre (N/m). 3.7 apparent tensile strength b tensile strength of the centre-notched fracture toughness test piece Note 1 to entry: The apparent tensile strength is reported in newtons per metre (N/m). 3.8 apparent strain at break strain at break of the centre-notched fracture toughness te
37、st piece Note 1 to entry: The apparent strain at break is dimensionless and usually reported as a percentage. 3.9 fracture toughness energy release rate at structural instabilit y of notched paper or board panels under in-plane tensile loading 3.10 ISO fracture strength b tensile strength of the edg
38、e-notched ISO paper web geometry used in this Technical Specification2 ISO 2013 All rights reserved ISO/TS 17958:2013(E) 3.11 ISO fracture strain strain at break of the edge-notched ISO paper web geometry used in this Technical Specification 4 Principle Two different kinds of test pieces, un-notched
39、 and notched, of given dimensions are subjected to constant rate of elongation using a tensile testing machine recording the tensile force and elongation. From the recorded data of the un-notched test pieces, the tensile strength, strain at break, tensile energy absorption, and tensile stiffness are
40、 determined. From the recorded data of the notched test pieces, the apparent tensile strength and apparent strain at break are determined. The parameters of the un- notched test pieces in combination with the parameters of the notched test pieces are used to calculate the fracture toughness of the m
41、aterial. The required calculations are treated in Clause 9. 5 Apparatus 5.1 Tensile testing machine, as described in ISO 1924-3. The tensile testing machine shall be capable of testing both 15 mm wide and 50 mm wide test pieces. 5.2 Anti-buckling guide, used to keep the notched region of the fractur
42、e toughness test piece flat during the fracture toughness test. The anti-buckling guide shall consist of two supports with parallel, flat, smooth low-friction surfaces, preferably made of steel or aluminium that shall cover the total width of the test piece and a length of 15 mm on each side of the
43、notch. A compression force of (0,6 0,2) N shall be applied to the fracture toughness test piece by the supports, before the separation of the supports is fixed. The fixed separation of the supports shall then be retained during the reminder of the fracture toughness test. One possible solution to pr
44、event out-of-plane buckling of the fracture toughness test piece is shown in Figure 2. The paper test piece (1) is placed between a stationary upper support (2) and a movable lower support (3). The lower support, which is free to slide vertically on roller bearings (7), is brought into contact with
45、the test piece. The specified compression force is applied by the spring (5) to the paper test piece via the lower support. The position of the lower support is then fixed by the pneumatic cylinder (4) via the thin metal blade (6). ISO 2013 All rights reserved 3 ISO/TS 17958:2013(E) Key 1 paper test
46、 piece 2 upper support 3 lower support 4 pneumatic cylinder 5 spring 6 thin metal blade 7 roller bearings Figure 2 Illustration of one possible solution to achieve anti-buckling 5.3 Computer, means for numerical calculation of fracture toughness and predictions of fracture strength and fracture stra
47、in, in accordance with the formulae given in this Technical Specification. 5.4 Cutting device(s), used for cutting tensile and fracture toughness test pieces. The cutting device(s) shall be able to cut (15 0,1) mm wide tensile test pieces and (50 0,1) mm wide fracture toughness test pieces (2W), res
48、pectively. 5.5 Device for making a notch, used to manufacture a centre-notch in each fracture toughness test piece. The device shall be able to produce a (20 0,1) mm long straight centre-notch (2a). The notch shall be oriented perpendicular to the loading direction with a precision of 5 and have a c
49、entral location with respect to both the width and the length of the test piece. The end of the notch shall be situated (15 0,1) mm from the edge of the test piece. The position of the notch in the length direction shall be (50 5) mm (h) from each clamp in the testing apparatus. A description of the test piece is given in Figure 3. NOTE One possible device that is able to cut the notch with the required precision consists of a sharp razor bl
