1、BRITISH STANDARD BS 1932-2: 1989 Incorporating Amendment No. 1 Testing the strength of yarns and threads from packages Part 2: Methods for determination of knot strength and loop strengthBS1932-2:1989 This British Standard, having been prepared under the direction of the Textiles and Clothing Standa
2、rds Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 31 March 1989 BSI 08-1999 First published January 1953 First revision July 1966 Second revision March 1989 The following BSI references relate to the work on this standard: Committee reference TCM/24 Draft fo
3、r comment 87/38880 DC ISBN 0 580 17058 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Textiles and Clothing Standards Committee (TCM/-) to Technical Committee TCM/24, upon which the following bodies were represented: Association of Co
4、nsulting Scientists British Polyolefin Textiles Association British Textile Employers Association Confederation of British Wool Textiles Limited International Wool Secretariat Man-made Fibres Producers Committee Ministry of Defence SATRA Footwear Technology Centre Soap and Detergent Industry Associa
5、tion Society of Dyers and Colourists Society of Motor Manufacturers and Traders Limited Textile Institute Textile Research Council Amendments issued since publication Amd. No. Date of issue Comments 9046 June 1996 Indicated by a sideline in the marginBS1932-2:1989 BSI 08-1999 i Contents Page Committ
6、ees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Apparatus 1 5 Atmospheres for conditioning and testing 1 6 Test specimens 1 7 Procedure 1 8 Calculation and expression of results 2 9 Test report 2 Figure 1 Knots in yarn 2 Publications referred to Inside back c
7、overBS1932-2:1989 ii BSI 08-1999 Foreword This revision of BS 1932-2 has been prepared under the direction of the Textiles and Clothing Standards Committee. It supersedes BS1932-2:1966, which is withdrawn. Methods for determination of breaking strength and breaking extension are given in BSENISO2062
8、. If a textile yarn is looped or knotted, its tensile strength may be reduced. This can arise when a yarn is bent to a small radius of curvature (as in sewing or knitting) or knotted (as in the manufacture of nets). In order to assess the importance of these effects, two tests are described. One ass
9、esses the strength of interlinked looped lengths of yarn and the other the strength of a knotted yarn. The knot strength test described in this Part of BS1932 is not intended to assess the efficiency of any given type of knot for joining together two separate lengths of yarn. This revision of BS 193
10、2-2 is based on the recently revised BSENISO2062, in which the principal change was replacement of the previous method, involving a fixed time to break, by a constant rate of extension method. At the time of publication of this standard, no corresponding International Standard exists. A British Stan
11、dard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover,
12、 an inside front cover, pages i and ii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS1932-2:1989 BSI 08-1999 1 1 Scope This
13、Part of BS 1932 describes methods for determination of the knot strength of specimens of yarn in each of which a single overhand knot has been tied and the loop strength of interlinked looped lengths of yarn. The methods provide for determination of the strength of yarns both in equilibrium with the
14、 standard temperate atmosphere for testing and in the wet state. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS1932, the definitions in BSENISO2062 apply, together with the following. 2.1 knot bre
15、aking strength the maximum force applied in stretching to rupture a specimen of yarn in which a single overhand knot has been tied 2.2 knot strength ratio the ratio of the knot breaking strength measured in accordance with this Part of BS1932 to the yarn breaking strength measured in accordance with
16、 BSENISO2062, both breaking strengths being determined under the same conditions (e.g. type of machine, grips) 2.3 loop breaking strength the maximum force applied to a specimen comprising two interlinked lengths of yarn in stretching it to rupture 2.4 loop strength ratio the ratio of the loop break
17、ing strength determined in accordance with this Part ofBS1932 to twice the yarn breaking strength measured in accordance withBS EN ISO2062, both breaking strengths being determined under the same conditions(e.g.type of machine, grips) 3 Principle 3.1 Knot strength A length of yarn, in the middle of
18、which a single overhand knot has been tied, is extended until it breaks. The knot breaking strength is recorded. 3.2 Loop strength Two interlinked looped lengths of yarn are extended until breakage of one loop occurs. The loop breaking strength is recorded. 4 Apparatus The apparatus described in BS
19、EN ISO2062 shall be used. 5 Atmospheres for conditioning and testing The atmospheres for pre-conditioning, conditioning and testing shall be as defined in BS1051, i.e.: a) for pre-conditioning: an atmosphere having a relative humidity between10% and25% and a temperature not exceeding50 C; b) for con
20、ditioning and testing: an atmosphere having a relative humidity of65 2% and a temperature of20 2 C. 6 Test specimens The number of test specimens shall be as described in BSENISO2062. 7 Procedure 7.1 General Carry out the procedure described in BSENISO2062, with the modifications given in7.2 and7.3.
21、 7.2 Knot strength Withdraw 60cm to 70cm of yarn from the sample to be tested. Tie a single overhand knot at approximately the middle of the specimen taking care to avoid any displacement of twist, and mount the specimen in the tensile testing machine. For S-twisted yarns 1)and for twistless yarns,
22、use an S-knot and for Z-twisted yarns use a Z-knot (seeFigure 1). Apply a pretension to the specimen before it is finally secured in the grips as follows: a) for conditioned specimens: 0.5 0.1 cN/tex; b) for wet specimens: 0.25 0.05 cN/tex. Record the breaking strength of each specimen. Note whether
23、 or not failure occurs at the knot, i.e.actually at the point of the knot and not merely in the vicinity of it. If the yarn breaks within 5mm of the point of contact of the yarn and the gripping device, obtain another specimen and make a fresh test. 1) For plied and cabled yarns the twist direction
24、refers to the final twist.BS1932-2:1989 2 BSI 08-1999 7.3 Loop strength Form a length of yarn from the sample to be tested into a loop and clamp the two ends of the yarn close together and parallel to each other in one grip of the tensile testing machine. Pass a second length of yarn 2)through the l
25、oop to form another looped length and clamp its two ends similarly in the other grip so that the point of contact of the two loops is approximately midway between the gripping points, taking precautions to avoid any displacement of the twist. Apply a pretension to the composite specimen before it is
26、 finally secured in the grips, as follows: a) for conditioned specimens: 1.0 0.1 cN/tex 3) ; b) for wet specimens: 0.5 0.05 cN/tex 3) . Set the machine in operation and stretch the yarn until it breaks. Record the breaking strength of each specimen. Note whether or not failure occurs at the point of
27、 intersection of the loops. If the yarn breaks within 5 mm of the point of contact of the yarn and the gripping device, obtain another specimen and make a fresh test. 8 Calculation and expression of results 8.1 General For the calculations described in 8.2 to 8.7, do not use the results of any tests
28、 in which the specimens broke within5mm of the point of contact of the yarn with the gripping device. 8.2 Knot breaking strength Calculate the mean of the knot breaking strength results, expressing the result in newtons to two significant figures. Calculate the coefficient of variation of the knot b
29、reaking strength. 8.3 Knot strength ratio Calculate the knot strength ratio by dividing the mean knot breaking strength (see 8.2) by the mean yarn breaking strength, as measured in accordance with BSENISO2062, both breaking strengths being determined under the same testing conditions (e.g. type of m
30、achine, grips). 8.4 Loop breaking strength Calculate the mean of the loop breaking strength results, expressing the result in newtons to two significant figures. Calculate the coefficient of variation of the loop breaking strength. 8.5 Loop strength ratio Calculate the loop strength ratio by dividin
31、g the mean loop breaking strength (see 8.4) by twice the mean yarn breaking strength, as measured in accordance with BSENISO 2062, both breaking strengths being determined under the same testing conditions (e.g. type of machine, grips). 9 Test report The test report shall include the following parti
32、culars: a) the number and date of this British Standard, i.e. BS 1932-2:1989; b) the identification of the sample tested; c) the results obtained, expressed as in clause 8; d) the condition in which the specimens were tested, i.e. conditioned or wet; e) the number of results rejected; f) whether len
33、gths of yarn from two packages were used for determination of loop strength (see7.3). 2) This yarn should be from the same package. If required, yarn from a different package may be used and this fact reported in accordance with item f) of clause 9. 3) Tex here refers to the linear density (in the c
34、onditioned state) of the yarn being tested and not to the resultant linear density of the looped specimen. Figure 1 Knots in yarnBS1932-2:1989 BSI 08-1999 Publications referred to BS 1051, Glossary of terms relating to the conditioning, testing and mass determination of textiles. BS EN ISO 2062, Tex
35、tiles Yarns from packages Determination of single-end breaking force and elongation a break. BS 1932-2: 1989 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards i
36、n Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our p
37、roducts and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel:02089969000. Fax:02089967400. BSI offers membe
38、rs an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel:02089969001. Fax:02089967001. In re
39、sponse to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as BritishStandards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards throu
40、gh its Library and its Technical Help to Exporters Service. Various BSI electronic information services are also available which give details on all its products and services. Contact the Information Centre. Tel:02089967111. Fax:02089967048. Subscribing members of BSI are kept up to date with standa
41、rds developments and receive substantial discounts on the purchase price of standards. For details of these and other benefits contact Membership Administration. Tel:02089967002. Fax:02089967001. Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the pu
42、blications of the internationalstandardization bodies. Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, photocopying, recording or otherwise without prior written pe
43、rmission from BSI. This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size, type or grade designations. If these details are to be used for any other purpose than implementation then the prior written permission of BSI must be obtained. If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel:02089967070.
