BS 3356-1990 Method for determination of bending length and flexural rigidity of fabrics《织物弯曲长度和挠曲硬度的测定方法》.pdf

1、BRITISH STANDARD BS3356:1990 Incorporating Amendment No.1 Method for Determination of bending length and flexural rigidity of fabricsBS3356:1990 This British Standard, having been prepared under the directionof the Textiles and Clothing Standards Policy Committee, was published underthe authority of

2、 the Board of BSI and comes intoeffecton 31 August1990 BSI06-1999 First published March1961 Second edition August1990 The following BSI references relate to the work on this standard: Committee referenceTCM/24 Draft for comment89/36835DC ISBN 0 580 19293 8 Committees responsible for this British Sta

3、ndard The preparation of this British Standard was entrusted by the Textiles and Clothing Standards Policy Committee (TCM/-) to Technical Committees TCM/24, upon which the following bodies were represented: Association of Consulting Scientists British Nonwovens Manufacturers Association British Poly

4、olefin Textiles Association British Textile Employers Association British Textile Machinery Association British Textile Technology Group Confederation of British Wool Textiles Limited International Wool Secretariat Man-made Fibres Producers Committee Ministry of Defence SATRA Footwear Technology Cen

5、tre Soap and Detergent Industry Association Society of Dyers and Colourists Textile Institute Amendments issued since publication Amd. No. Date of issue Comments 6337 June 1991 Indicated by a sideline in the marginBS3356:1990 BSI 06-1999 i Contents Page Committees responsible Inside front cover Fore

6、word ii 1 Scope 1 2 Principle 1 3 Definitions 1 4 Apparatus 1 5 Atmospheres for conditioning and testing 1 6 Test specimens 2 7 Procedure 2 8 Calculation and expression of results 3 9 Test report 3 Figure 1 Apparatus for determining flexural rigidity 2 Publications referred to Inside back coverBS335

7、6:1990 ii BSI 06-1999 Foreword This British Standard has been prepared under the direction of the Textiles and Clothing Standards Policy Committee and forms a revision of BS3356:1961 which is withdrawn. The principal change introduced in this revision is that the method has been brought up to date b

8、y making minor changes throughout the text. At the time of publication of this British Standard no corresponding international standard exists. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct appl

9、ication. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyright date) a

10、nd may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS3356:1990 BSI 06-1999 1 1 Scope This British Standard describes a method for determination of the bending length and flexural rigidity of textile fabrics and certain nonwovens by means

11、of a fixed-angle flexometer. The method is not applicable to fabrics that curl or twist badly when cut into small pieces, nor to fabrics that show a noticeable time effect when allowed to bend under their own mass. NOTE 1The use of this method for nonwovens should be agreed between the interested pa

12、rties. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle A rectangular strip of fabric is supported on a horizontal platform in a direction perpendicular to one edge of the platform. The strip is extended in the direction of its length

13、 so that an increasing part overhangs and bends down under its own mass. When the tip of the specimen has reached a plane passing through the edge of the platform and inclined at an angle of41.5 below the horizontal, the overhanging length is equal to twice the bending length of the specimen. The fl

14、exural rigidity is obtained from the bending length and the mass per unit area of the fabric. NOTEFor the majority of fabrics the bending length will not exceed100mm, in which case the overhanging length will not exceed200mm. 3 Definitions For the purposes of this British Standard the following defi

15、nitions apply. 3.1 flexural rigidity the ratio of the small change in bending movement per unit width of the material to the corresponding small change in curvature, expressed in mgcm NOTEThis quantity is a measure of the resistance of the fabric to bending by external forces. It is related to the q

16、uality of stiffness that is appreciated when a fabric is handled, in the sense that fabric having a high flexural rigidity tends to feel stiff. 3.2 bending length the cube root of the ratio of the flexural rigidity to the mass per unit area of the fabric expressed in cm. It is equal to the length of

17、 a rectangular strip of material that will bend under its own mass to an angle of7.1 NOTE 1This quantity is one of the factors that determines the manner in which a fabric drapes. It is related to the quality of stiffness that is appreciated by visual examination of the draped material, in the sense

18、 that fabrics having a high bending length tend to drape stiffly. NOTE 2Samples with the warp threads parallel to the long edge are identified by warp bending length and warp flexural rigidity. Samples with the weft threads parallel to the long edge are identified by weft bending length and weft fle

19、xural rigidity. 4 Apparatus 4.1 Fixed-angle flexometer as shown in Figure 1, comprising the following essential features. A slide S rests on a horizontal platform P. The upper surface of the slide is calibrated with a scale which indicates bending length directly in units and tenths of a unit. For t

20、he angle of inclination of41.5 (see clause3) unit graduations of the scale on the slide are uniformly spaced20mm apart. When the front edge of the slide coincides with the front edge of P, the zero of the scale on S coincides with a datum line D on the instrument. Two sighting lines L 1and L 2pass t

21、hrough the upper forward edge of P and are inclined at an angle of41.5 below the horizontal, and are inscribed on the transparent side pieces of the instrument. The under surface of S is covered with a layer of high friction material such as sheet rubber and the upper surface of P is polished so tha

22、t, when S is moved, it will carry forward a specimen placed between the slide and the surface P. The width of the slide S shall be25mm and its mass shall be180 2g. NOTE 1The range of the instrument is governed by its size. It is convenient to be able to determine bending lengths of about80mm to100mm

23、 in which case the overhanging length of the specimen is160mm to200mm. NOTE 2Except where otherwise indicated the above requirements are nominal. 4.2 Means of measuring length to an accuracy of at least1mm. 4.3 Means of measuring time to an accuracy of1s. 5 Atmospheres for conditioning and testing A

24、tmospheres for conditioning and testing shall be as follows. a) For preconditioning, an atmosphere of relative humidity not more than10% and of temperature not more than50C shall be used 1) . 1) An oven at50C under ordinary room conditions will give the required low humidity. For some fabrics the te

25、mperature of50C may not be permissible. In such case the relative humidity of10% should be obtained by the removal of moisture from the air used for preconditioning.BS3356:1990 2 BSI 06-1999 b) The conditioning and testing atmosphere shall be the standard temperate atmosphere for testing textiles de

26、fined in BS1051, i.e.an atmosphere of652% relative humidity at a temperature of20 2 C. NOTEThe results can vary considerably if the specified conditions are not used. 6 Test specimens Cut rectangular specimens251mm wide and2001mm long from the fabric to be tested. At least three specimens shall be t

27、aken with their warp threads parallel to the long edge (subsequently referred to as warp specimens), and an equal number with their weft threads parallel to the long edge (subsequently referred to as weft specimens). Cut the specimens so that, as far as possible, no two warp specimens contain the sa

28、me warp threads and no two weft specimens contain the same weft threads. Selvedges, end pieces and creased or folded places shall not be included in the specimens. Handle the fabric and the specimens as little as possible. NOTEFor fabrics other than woven fabrics, specimens should be taken in the ma

29、chine and cross machine directions. 7 Procedure Precondition the test specimens for at least4h in the atmosphere specified in clause5 a) and then expose them to the standard atmosphere for testing see clause5 b) for not less than24h or until the mass of a specimen does not change by more than0.25% a

30、t intervals of2h. Test the specimens without their removal from this atmosphere. Lay the specimen on a smooth horizontal surface terminated at one end by a straight edge, so that the length of the specimen is at right angles to, and one end is level with, that edge. Move the specimen lengthwise over

31、 the edge at a uniform rate of approximately25mm in5s, until the end of the specimen comes into line with the two lines L 1and L 2 . Measure the length of fabric protruding beyond the edge. Make a similar determination with the other face of the same end of the specimen uppermost. Test the other fiv

32、e specimens in the same way. NOTEIt will be found helpful in carrying out this procedure to place the flexometer so that the zero of the scale lies towards the observer and at a level that enables the scale to be read with comfort. The position of the end of the specimen relative to the sighting lin

33、es may then be observed in a mirror suitably placed or attached to one side of the instrument. Figure 1 Apparatus for determining flexural rigidityBS3356:1990 BSI 06-1999 3 8 Calculation and expression of results Read the bending length direct from the scale. Calculate the mean bending length C for

34、warp and weft directions separately. Using the appropriate mean value, calculate the flexural rigidity G, in mgcm, separately for the warp and weft directions by the following formula: G=0.10MC 39 Test report The test report shall include the following particulars: a) number and date of this British

35、 Standard, i.e.BS3356:1990; b) details of the sample tested; c) mean warp bending length; d) mean weft bending length; e) mean warp flexural rigidity; f) mean weft flexural rigidity; g) number of warp specimens tested; h) number of weft specimens tested. where M is the mass per unit area of the fabr

36、ic, in gm 2determined in accordance with BS2471.4 blankBS3356:1990 BSI 06-1999 Publications referred to BS1051, Glossary of terms relating to the conditioning, testing and mass determination of textiles. BS2471, Methods of test for textiles woven fabrics determination of mass per unit length and mas

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