1、BRITISH STANDARD BS 4952:1992 Methods of test for Elastic fabricsBS4952:1992 This British Standard, having been prepared under the directionof the Textiles and Clothing Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 March 1992 BSI 01-
2、1999 First published October 1973 Second edition March 1992 The following BSI references relate to the work on this standard: Committee reference TCM/24 Draft for comment 90/46489 DC ISBN 0 580 20491 X Committees responsible for this British Standard The preparation of this British Standard was entr
3、usted by the Textiles and Clothing Standards Policy Committee (TCM/-) to Technical Committee TCM/24, upon which the following bodies were represented: Association of Consulting Scientists British Nonwovens Manufacturers Association British Polyolefin Textiles Association British Textile Confederatio
4、n British Textile Machinery Association British Textile Technology Group British Throwsters Association Confederation of British Wool Textiles Limited Furniture Industry Research Association International Wool Secretariat Ministry of Defence North East Lancashire Textile Manufacturers Association SA
5、TRA Footwear Technology Centre Soap and Detergent Industry Association Society of Dyers and Colourists Textile Finishers Association Textile Institute Amendments issued since publication Amd. No. Date CommentsBS4952:1992 BSI 01-1999 i Contents Page Committees responsible Inside front cover Foreword
6、ii Section 1. General 1.1 Scope 1 1.2 Definitions 1 1.3 Apparatus 1 1.4 Test specimens 1 1.5 Conditioning and testing 4 1.6 Properties to be tested in accordance with existing British Standards 4 Section 2. Test methods 2.1 Determination of extension at a specified force 5 2.2 Determination of modul
7、us 5 2.3 Determination of tension decay 5 2.4 Determination of residual extension 6 2.5 Method for fatiguing specimens 6 2.6 Determination of fatigue set 7 2.7 Determination of elastomeric thread breaks 7 2.8 Determination of runback 7 2.9 Method for ageing specimens 8 Figure 1 Line contact clamps 2
8、 Figure 2 Loop assembly clamps 2 Figure 3 Looped specimen 3 Publication(s) referred to Inside back coverBS4952:1992 ii BSI 01-1999 Foreword This British Standard has been prepared under the direction of the Textiles and Clothing Standards Policy Committee. It supersedes BS4952:1973 and BS4294:1968 w
9、hich are withdrawn. The principal changes introduced by this revision are that this edition of BS 4952 uses a similar format to BS 5441 and lists properties which can be tested in accordance with existing British Standards. The test procedures have been brought up-to-date by deleting test variants t
10、hat are no longer in use and the retained techniques have been refined. The standard also includes provisions for testing looped specimens in addition to straight specimens. Methods already published as British Standards have not been reproduced, but a list is given, in 1.6, of other test methods th
11、at can be of use in the assessment of elastic fabrics. A British Standard 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
12、 obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 8, 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
13、 on theinside front cover.BS4952:1992 BSI 01-1999 1 Section 1. General 1.1 Scope This British Standard describes methods of test specific to both narrow and wide elastic fabrics. The test methods are applicable to woven and to warp knitted and weft knitted fabrics but certain tests can also be appli
14、cable to stretch fabrics which are obtained by the use of elastomeric bulked yarns or by a process such as slack mercerization. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 1.2 Definitions For the purposes of this British Standard the following
15、 definitions apply. 1.2.1 elastic fabrics fabrics, which incorporate elastomeric threads 1.2.2 elastomer a macromolecular material which returns rapidly to approximately its initial dimensions and shape after substantial deformation by a weak stress and release of stress 1.2.3 modulus the tensile fo
16、rce in the test specimen required to produce a specified elongation 1.3 Apparatus 1.3.1 Metal scale, graduated in millimetres. 1.3.2 Autographic constant rate-of-extension stress/strain apparatus (unless otherwise indicated in the particular test procedure) capable of cycling between zero extension
17、and either a predetermined force or a predetermined extension and capable of maintaining a specimen either under a constant tension or at a constant elongation. The apparatus shall be provided with means for recording the extension of the test specimen and the corresponding force. It shall be equipp
18、ed with either line contact clamps for straight specimens (see1.3.3.2) or loop assembly clamps (see 1.3.3.3). 1.3.3 Clamps 1.3.3.1 General The central points of the two clamps shall be in the line of pull and the testing device shall be calibrated with the clamps in position. The clamps shall be cap
19、able of allowing the specimens to be maintained either at a constant elongation or under a constant force as appropriate for the test to be performed. 1.3.3.2 Line contact clamps Line contact clamps as shown in Figure 1 shall consist of two jaws, one being a flat steel plate, the other having a conv
20、ex 3 mm radius. The line of contact of the jaws shall be at right angles to the line of pull, and their clamping faces shall be in the same plane. The jaws shall be capable of holding the test specimen without allowing it to slip, shall be designed so that they do not cut or otherwise weaken the spe
21、cimen and shall be not less than the width of the specimen. 1.3.3.3 Loop assembly clamps Loop assembly clamps shall be as shown in Figure 2 and shall essentially comprise two removable steel bars of circular cross section and 4mm in diameter, around which the specimen passes and by which it is exten
22、ded as the bars move apart. The axes of the bars shall be at right angles to the line of pull and shall be in the same plane. 1.3.3.4 Gauge length and specimen length under extension In the case of line contact clamps, the gauge length and the length of the extended test specimen at any time is meas
23、ured as the distance between the lines of contact of the two jaws. Where specimen length is to be measured after removal of the specimen from the jaws, the gauge length marks shall be drawn on the specimen before it is inserted into the clamps. NOTEThe method of marking should be such as to prevent
24、damage to the specimen. In the case of loop assembly jaws, the gauge length is measured as the circumference around the loop bars. 1.4 Test specimens 1.4.1 General Take samples of fabric from which test specimens will be cut to represent the fabric under test. Prepare the specimens according to whet
25、her machine direction or cross direction stretch of the fabric is to be tested. Where possible test at least five specimens in each direction. 1.4.2 Preparation of specimens 1.4.2.1 General Prepare specimens in accordance with 1.4.2.2 to1.4.2.5 as appropriate. NOTEStraight specimens and looped speci
26、mens do not necessarily give the same results. BS4952:1992 2 BSI 01-1999 Figure 1 Line contact clamps Figure 2 Loop assembly clampsBS4952:1992 BSI 01-1999 3 1.4.2.2 Straight specimens Fabrics 50mm and below in width shall be tested full width in a lengthwise direction. For fabrics greater than 50mm
27、in width, specimens 50mm wide, excluding any fringe, shall be prepared such that they are of sufficient length to provide a nominal gauge length of 100mm. 1.4.2.3 Looped specimens Fabrics 75mm and below in width shall be tested full width in a lengthwise direction. For fabrics greater than 75mm in w
28、idth, specimens 75 mm wide, excluding any fringe shall be prepared of length 250mm. Mark a line 25mm from each end, parallel to the short dimension see Figure 3(a). Fold the specimen in half parallel to the short dimension and, starting in the centre of the line, sew along the line to form the strip
29、 into a loop, turning at the edge without breaking the threads, returning along the same line to the other edge and turning again to finish in the centre see Figure 3(b). The stitch, sewing thread and stitch density shall be such as to withstand the testing forces, i.e. to prevent the specimen openi
30、ng on extending. Figure 3 Looped specimenBS4952:1992 4 BSI 01-1999 1.4.2.4 Specimens of woven fabric For fabrics liable to fray during testing, cut specimens 25 mm wider than the required testing width and fray them down by removing excess threads in approximately equal numbers from each of the long
31、er edges of the cut strip until the width of the specimen is as specified in 1.4.2.2 or 1.4.2.3. 1.4.2.5 Specimens of weft knitted fabrics Prevent the cut edges of weft knitted test specimens from laddering by a method which will neither restrict the extension and retraction of the fabric, nor alter
32、 its stress/strain characteristics to any significant extent. NOTEIn some cases it is possible to use an expandable seam, or alternatively the cut edges could be sealed with a light application of latex adhesive followed, when the latex is dry, by a dusting of talc to prevent sticking. 1.5 Condition
33、ing and testing 1.5.1 Atmosphere Conditioning and testing shall be carried out in the standard temperate atmosphere for testing textiles as defined in BS 1051, i.e. a temperature of 20 2 C and relative humidity of 652%. 1.5.2 Conditioning of samples Condition the samples from which the test specimen
34、s are to be taken for a period of not less than 16h in a free, unrestrained state in the standard temperate atmosphere for testing textiles (see1.5.1). In cases of dispute, precondition the test specimens for 4 h at a relative humidity not exceeding 10% at a temperature not greater than 52C. An oven
35、 at 52 C under ordinary room conditions will give the required low humidity. Then expose the test specimens to the standard temperate atmosphere for testing textiles (see 1.5.1) for at least 24h before testing in, and without removal from, this atmosphere. 1.6 Properties to be tested in accordance w
36、ith existing British Standards A number of properties of elastic fabrics can be tested in accordance with other appropriate British Standards, which include the following. BS 1006:E03 at an active chlorine concentration of 100 mg/L for determination of colour fastness to swimming-bath water. BS 1930
37、 for determination of width of woven or knitted fabrics when relaxed at zero tension. BS 2471 for determination of mass per unit length and mass per unit area. BS 2862 for determination of number of threads per unit length. BS 4323 for determination of dimensional change of fabrics induced by free s
38、team. BS 5441 for determination of wales and courses per unit length in knitted fabrics. BS 5807 for determination of dimensional change on domestic laundering.BS4952:1992 BSI 01-1999 5 Section 2. Test methods 2.1 Determination of extension at a specified force 2.1.1 Apparatus Use apparatus as descr
39、ibed in 1.3.2 and 1.3.3. 2.1.2 Procedure 2.1.2.1 Straight specimens Set the clamps of the tensile testing machine to 100mm apart. Clamp a test specimen centrally in the stationary clamp so that its longitudinal axis passes through the centre points of the front edges of the jaws. Either: a) apply a
40、pre-tension of 2 N; or b) slack-mount the specimen, with any extension that occurs prior to the force reaching the pre-tension level (as indicated on an autographic recording) being considered as part of the slack, ultimately to be added to the gauge length. Clamp the free end of the test specimen i
41、n the second clamp. Set the rate of extension and retraction of the specimen to 500 mm/min. Cycle the specimen twice between zero extension and the specified force. Record, from the force versus extension graph produced, the elongation at the specified force on the second cycle. 2.1.2.2 Looped speci
42、mens Set the gauge length such that the circumference around the loop bars is 200 mm. Slide the loop bars open in order to position the looped specimen, after which, close the bars. Adjust the position of the specimen around the bars so that the seam lies midway between the bars. Set the rate of ext
43、ension and retraction of the specimen to 500 mm/min. Cycle the specimen twice between zero extension and the specified force. Record, from the force versus extension graph produced, the elongation at the specified force on the second cycle. 2.1.3 Test report The following shall be reported: a) speci
44、fied force used; b) percentage elongation for each specimen and their arithmetic mean; c) direction of test of the fabric, i.e. either machine direction or cross direction; d) specimen type, i.e. whether straight or looped; e) specimen width. 2.2 Determination of modulus 2.2.1 Apparatus Use apparatu
45、s as described in 1.3.2 and 1.3.3. 2.2.2 Procedure Read from the force versus extension curves as described in 2.1, the force on the extension and/or recovery curves on the second cycle, at intervals of elongation as arranged between the interested parties. 2.2.3 Test report The following shall be r
46、eported: a) modulus, i.e. force (in N) at each value of elongation where readings have been taken, the value of each elongation at which modulus reading has been taken and whether these were from the extension or retraction portion of the cycle, and their arithmetic mean; b) direction of test of the
47、 fabric, i.e. either machine direction or cross direction; c) specimen type, whether straight or looped; d) specimen width. 2.3 Determination of tension decay 2.3.1 Principle The test specimen is stretched to a specified elongation and the tension recorded. The elongation is maintained for 5min duri
48、ng which the decay of tension over this period is determined. 2.3.2 Apparatus Use apparatus as described in 1.3.2 and 1.3.3.2. 2.3.3 Test specimens Straight specimens as described in 1.4.2.2 shall be used. 2.3.4 Procedure The rate of extension and retraction shall be500mm/min. Set the separation of
49、the clamps to give a specimen gauge length L 1of 100mm. Mount the test specimen in such a way that it is straight and untensioned. Set the cycling controls to cycle between zero extension and a force of either5.0N/cm or 10.0 N/cm as agreed between interested parties. After cycling twice to this force, and without a pause, extend the specimen at the specified rate, to the specified elongation and record the maximum force. Maintain the specimen at this elongation for 5min after which time again record the force.BS4952:1992 6 BSI 01-1999 The tension decay
