1、Designation: D1388 08 (Reapproved 2012)D1388 14Standard Test Method forStiffness of Fabrics1This standard is issued under the fixed designation D1388; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the measurement of stiffness
3、 properties of fabrics. Bending length is measured and flexural rigidityis calculated. Two procedures are provided.1.1.1 Option ACantilever Test, employing the principle of cantilever bending of the fabric under its own mass.1.1.2 Option BHeart Loop Test, employing the principle of a loop formed in
4、a fabric strip and hung vertically.1.2 This test method applies to most fabrics including woven fabrics, air bag fabrics, blankets, napped fabrics, knitted fabrics,layered fabrics, pile fabrics. The fabrics may be untreated, heavily sized, coated, resin-treated, or otherwise treated.1.3 The values s
5、tated in SI units are to be regarded as the standard. The U.S. customary units may be approximate.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health
6、 practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2904 Practice for InterlaboratoryTesting of aTextileTest Method that Produces Normally
7、 Distributed Data (Withdrawn 2008)3D2906 Practice for Statements on Precision and Bias for Textiles (Withdrawn 2008)3D3776 Test Methods for Mass Per Unit Area (Weight) of FabricD4850 Terminology Relating to Fabrics and Fabric Test Methods3. Terminology3.1 For all terminology relating to D13.59, Fabr
8、ic Test Methods, General, refer to Terminology D4850.3.1.1 The following terms are relevant to this standard: bending length, cross-machine direction, CD, fabric, flexural rigidity,machine direction, MD, stiffness.3.2 For all other terminology related to textiles, refer to Terminology D123.4. Summar
9、y of Test Method Options4.1 Option A, Cantilever TestAspecimen is slid at a specified rate in a direction parallel to its long dimension, until its leadingedge projects from the edge of a horizontal surface. The length of the overhang is measured when the tip of the specimen isdepressed under its ow
10、n mass to the point where the line joining the top to the edge of the platform makes a 0.724 rad (41.5) anglewith the horizontal. From this measured length, the bending length and flexural rigidity are calculated.4.2 Option B, Heart Loop TestA strip of fabric is formed into a heart-shaped loop. The
11、length of the loop is measured whenit is hanging vertically under its own mass. From this measured length, the bending length and flexural rigidity are calculated.1 This test method is under the jurisdiction ofASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.60 on
12、Fabric Test Methods, Specific.Current edition approved July 1, 2012July 1, 2014. Published August 2012August 2014. Originally approved in 1956. Discontinued 1995 and reinstated as D1388 96.Last previous edition approved in 20082012 as D1388D138808(2012).08. DOI: 10.1520/D1388-08R12.10.1520/D1388-14.
13、2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is re
14、ferenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends tha
15、t users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use
16、5.1 Both test options in this test method are considered satisfactory for acceptance testing of commercial shipments since currentestimates of between-laboratory precision are acceptable and the method is used extensively in the trade for acceptance testing.5.1.1 In case of a dispute arising from di
17、fferences in reported test results when using this test method for acceptance testing ofcommercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical biasbetween their laboratories. Competent statistical assistance is recommended for the
18、 investigation of bias. As a minimum, the twoparties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the typein question. Test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average resu
19、ltsfrom the two laboratories should be compared using the appropriate statistical analysis and an acceptable probability level chosenby the two parties before testing is begun. If a bias is found, either its cause must be found and corrected or the purchaser and thesupplier must agree to interpret f
20、uture test results with consideration to the known bias.5.2 In general, these procedures are more suitable for testing woven fabrics than knit fabrics.5.3 The Cantilever Test Option is the preferred procedure because it is simpler to perform. It is, however, not suitable for verylimp fabrics or thos
21、e that show a marked tendency to curl or twist at a cut edge.5.4 The Heart Loop Test Option is suitable for fabrics that show a tendency to curl or twist.5.5 Both options can provide a correlation with a subjective evaluation of a given fabric type. That is, a higher numberrepresents a stiffer fabri
22、c.5.6 The stiffness of a fabric may change with storage.5.7 No evidence has been found showing that bending length is dependent on the width. The tendency for specimens to curlor twist will affect the result, because of the rigidity provided at the edge. Consequently, the wider the strip, the less i
23、mportant isthe edge effect.6. Apparatus6.1 Option ACantilever Bending Tester4 (Fig. 1).6.1.1 Horizontal Platform, with a minimum area of 38 by 200 mm (1.5 by 8 in.) and having a smooth low-friction, flat surfacesuch as polished metal or plastic. A leveling bubble shall be incorporated in the platfor
24、m.6.1.1.1 Indicator, inclined at an angle of 0.724 6 0.01 rad (41.5 6 0.5) below the plane of the platform surface.6.1.1.2 Movable Slide, consisting of a metal bar not less than 25 by 200 mm (1 by 8 in.) by approximately 3 mm (18 in.) thickand having a mass of 270 6 5 g (0.6 6 0.01 lb).6.1.1.3 Scale
25、 and Reference Point, to measure the length of the overhang.6.1.1.4 Specimen Feed Unit, motorized4 (see Fig. 1) set to 120 mm/min (4.75 in./min) 65 %, or manual equivalent.6.1.2 Cutting Die25 6 1 mm by 200 6 1 mm (1 6 0.04 in. by 8 6 0.04 in.).6.2 Option BHeart Loop Tester.6.2.1 Clamp and Stand, for
26、 hanging the specimen.4 Apparatus is available commercially.FIG. 1 Example of a Motorized Cantilever Test ApparatusD1388 1426.2.2 Scale, suitably mounted on the stand for measuring the length of the specimen loop and calibrated either in cm (in.) ordirectly in bending length.NOTE 1If a constant stri
27、p length is adopted, the scale may be calibrated to read directly in units of bending length.6.2.3 Brass Bars, two, 25 75 3 6 0.1 mm (1 3 0.1256 0.005 in.).6.2.4 Pressure Sensitive Tape.6.2.5 Jig, constructed to allow positioning of the two bars with their inner edges parallel and at a distance from
28、 each other equalto the selected strip length.7. Sampling and Test Specimens7.1 Lot SampleAs a lot sample for acceptance testing, randomly select the number of rolls or pieces of fabric directed in anapplicable material specification or other agreement between the purchaser and the supplier. Conside
29、r the rolls or pieces of fabricto be the primary sampling units. In the absence of such an agreement, take the number of fabric rolls specified in Table 1.NOTE 2An adequate specification or other agreement between the purchaser and supplier requires taking into account the variability between rollso
30、r pieces of fabric and between specimens from a swatch from a roll or piece of fabric to provide a sampling plan with a meaningful producers risk,consumers risk, acceptable quality level, and limiting quality level.7.2 Laboratory SampleFor acceptance testing, take a swatch extending the width of the
31、 fabric and approximately 1 m (1 yd)along the machine direction from each roll or piece in the lot sample. For rolls of fabric, take a sample that will exclude fabricfrom the outer wrap of the roll or the inner wrap around the core of the roll of fabric, or any end piece.7.3 Direction of TestConside
32、r the long dimension of the specimen as the direction of test.7.4 Number of Test SpecimensFrom each laboratory sampling unit, take four specimens from the machine direction and fourspecimens from the cross-machine direction as applicable to a material specification or contract order.7.5 Cutting Test
33、 SpecimensCut the specimens to be used for the measurement of machine direction with the longer dimensionparallel to the machine direction. Cut the specimens to be used for the measurement of the cross-machine direction with the longerdimension parallel to the cross-machine direction. Label to maint
34、ain specimen identity.7.5.1 Take specimens, representing a broad distribution across the width and length, preferably along the diagonal of thelaboratory sample, and no nearer the edge than one-tenth its width. Ensure specimens are free of folds, creases, or wrinkles.Avoidgetting oil, water, grease,
35、 etc. on the specimens when handling.7.5.2 Cantilever TestCut test specimens 25 by 200 mm, 61 mm (1 by 8 in. 6 0.04 in.).7.5.3 Heart Loop TestNo standard size for the test specimen is required. Cut test specimens 50 mm (2 in.) longer than theselected strip length to allow for clamping at the ends. S
36、ee Table 2.7.5.3.1 Select a specimen width at least 25 mm (1 in.) and no more than 75 mm (3 in.) with respect to the tendency of the fabricto curl. For fabrics having a slight tendency to curl, a 25 6 1 mm (1 6 0.04 in.) wide specimen has been found to be satisfactory.As the tendency to curl becomes
37、 greater, increase the width up to a maximum of 75 mm (3 in.).7.5.3.2 Make several trial tests using various strip lengths selected from Table 2. Select a suitable strip length for acorresponding loop length from Table 2, such that the bending length is relatively independent of strip length.NOTE 3S
38、trip length is the circumferential length of the unclamped portion of the specimen.NOTE 4Specimen strip widths greater than 75 mm (3 in.) have not been investigated and are not recommended since reliability of results arequestionable.NOTE 5The bending length using the heart loop option is not entire
39、ly independent of the strip length. In general, the bending length rises with thestrip length up to a value that remains relatively constant as the strip length is further increased. An additional rise may further be encountered for muchlonger strip lengths. Whenever possible, compare fabrics in the
40、 range where bending length is independent of strip length.8. Preparation of Test Apparatus and Calibration8.1 Option ACantilever Test:8.1.1 Set the tester on a table or bench with the horizontal platform and inclined reference lines. Adjust the platform tohorizontal as indicated by the leveling bub
41、ble.8.1.2 Verify that the bend angle indicator is at the 0.724 rad (41.5) angle marked on the scale.TABLE 1 Number of Rolls, or Pieces, of Fabric in the Lot SampleNumber of Rolls or Piecesin Lot, Inclusive Number of Rolls or Pieces in Lot Sample1 to 3 all4 to 24 425 to 50 5over 50 10 % to a max of 1
42、0 rolls or piecesD1388 1439. Conditioning9.1 Precondition the specimens by bringing them to approximate moisture equilibrium in the standard atmosphere forpreconditioning textiles as directed in Practice D1776, unless otherwise directed in a material specification or contract order.9.2 After precond
43、itioning, bring the test specimens to moisture equilibrium for testing in the standard atmosphere for testingtextiles as directed in Practice D1776 or, if applicable, in the specified atmosphere in which the testing is to be performed, unlessotherwise directed in a material specification or contract
44、 order.10. Procedure10.1 Test the conditioned specimens in the standard atmosphere for testing textiles, which is 21 6 1C (70 6 2F) and 65 62 % relative humidity, unless otherwise directed in a material specification or contract order.10.2 Option ACantilever Test:10.2.1 Remove the movable slide. Pla
45、ce the specimen on the horizontal platform with the length of the specimen parallel to theplatform edge. Align the edge of the specimen with the line scribed on the right-hand edge of the horizontal platform.NOTE 6When known, place the specimen face-side up.10.2.2 Place the movable slide on the spec
46、imen, being careful not to change its initial position.10.2.3 For automatic testers, turn the tester switch on and watch the leading edge of the specimen closely. Turn the switch offthe instant the edge of the specimen touches the knife edge.10.2.4 For manual testers, move the clamped specimen by ha
47、nd in a smooth manner at approximately 120 mm/min (4.75in./min)6 5 % until the edge of the specimen touches the knife edge.10.2.5 Read and record the overhang length from the linear scale to the nearest 0.1 cm (0.1 in.).NOTE 7If the specimen has a tendency to twist, take the reference point at the c
48、enter of the leading edge. Do not measure specimens that twist morethan 0.785 rad (45).10.2.6 Test the face and back of both ends of each specimen for a total of four readings per specimen.10.3 Option BHeart Loop Test:10.3.1 Place the two bars parallel to one another on a horizontal surface such tha
49、t the inner edges are separated by a distanceequal to the selected strip length (see 6.2.5).10.3.2 Lay the test specimen across the two bars with the outer edge approximately 5 6 1 mm (0.5 6 0.005 in.) from one endof each bar.10.3.3 Attach one end of the specimen strip to one bar using pressure-sensitive tape, being careful to align to one edge of thebar. Apply just enough tension to the specimen to hold it taut, but without stretching, and attach the other specimen end to thesecond bar in a similar manner.TABLE 2 Table of Bending Lengt
