1、Designation: D1388 141Standard 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 number in parentheses indica
2、tes 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.1NOTEIn 10.3.4, “Rotate.the right-hand bar in a clockwise direction” was corrected to “co
3、unterclockwise” in October2015.1. Scope1.1 This test method covers the measurement of stiffnessproperties of fabrics. Bending length is measured and flexuralrigidity is calculated. Two procedures are provided.1.1.1 Option ACantilever Test, employing the principle ofcantilever bending of the fabric u
4、nder its own mass.1.1.2 Option BHeart Loop Test, employing the principleof a loop formed in a fabric strip and hung vertically.1.2 This test method applies to most fabrics includingwoven fabrics, air bag fabrics, blankets, napped fabrics, knittedfabrics, layered fabrics, pile fabrics. The fabrics ma
5、y beuntreated, heavily sized, coated, resin-treated, or otherwisetreated.1.3 The values stated in SI units are to be regarded as thestandard. The U.S. customary units may be approximate.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is th
6、eresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing Texti
7、lesD2904 Practice for Interlaboratory Testing of a Textile TestMethod that Produces Normally Distributed Data (With-drawn 2008)3D2906 Practice for Statements on Precision and Bias forTextiles (Withdrawn 2008)3D3776 Test Methods for Mass Per Unit Area (Weight) ofFabricD4850 Terminology Relating to Fa
8、brics and Fabric TestMethods3. Terminology3.1 For all terminology relating to D13.59, Fabric TestMethods, General, refer to Terminology D4850.3.1.1 The following terms are relevant to this standard:bending length, cross-machine direction, CD, fabric, flexuralrigidity, machine direction, MD, stiffnes
9、s.3.2 For all other terminology related to textiles, refer toTerminology D123.4. Summary of Test Method Options4.1 Option A, Cantilever TestA specimen is slid at aspecified rate in a direction parallel to its long dimension, untilits leading edge projects from the edge of a horizontal surface.The le
10、ngth of the overhang is measured when the tip of thespecimen is depressed under its own mass to the point wherethe line joining the top to the edge of the platform makes a0.724 rad (41.5) angle with the horizontal. From this mea-sured length, the bending length and flexural rigidity arecalculated.4.
11、2 Option B, Heart Loop TestA strip of fabric is formedinto a heart-shaped loop. The length of the loop is measuredwhen it is hanging vertically under its own mass. From thismeasured length, the bending length and flexural rigidity arecalculated.5. Significance and Use5.1 Both test options in this te
12、st method are consideredsatisfactory for acceptance testing of commercial shipmentssince current estimates of between-laboratory precision areacceptable and the method is used extensively in the trade foracceptance testing.5.1.1 In case of a dispute arising from differences inreported test results w
13、hen using this test method for acceptance1This test method is under the jurisdiction ofASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.60 on Fabric Test Methods,Specific.Current edition approved July 1, 2014. Published August 2014. Originallyapproved in 1956. Disco
14、ntinued 1995 and reinstated as D1388 96. Last previousedition approved in 2012 as D138808(2012). DOI: 10.1520/D1388-14E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, ref
15、er to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1testing of commercial shipments, the purc
16、haser and the sup-plier should conduct comparative tests to determine if there isa statistical bias between their laboratories. Competent statis-tical assistance is recommended for the investigation of bias.As a minimum, the two parties should take a group of testspecimens that are as homogeneous as
17、 possible and that arefrom a lot of material of the type in question. Test specimensshould then be randomly assigned in equal numbers to eachlaboratory for testing. The average results from the twolaboratories should be compared using the appropriate statis-tical analysis and an acceptable probabili
18、ty level chosen by thetwo parties before testing is begun. If a bias is found, either itscause must be found and corrected or the purchaser and thesupplier must agree to interpret future test results with consid-eration to the known bias.5.2 In general, these procedures are more suitable for testing
19、woven fabrics than knit fabrics.5.3 The Cantilever Test Option is the preferred procedurebecause it is simpler to perform. It is, however, not suitable forvery limp fabrics or those that show a marked tendency to curlor twist at a cut edge.5.4 The Heart Loop Test Option is suitable for fabrics thats
20、how a tendency to curl or twist.5.5 Both options can provide a correlation with a subjectiveevaluation of a given fabric type. That is, a higher numberrepresents a stiffer fabric.5.6 The stiffness of a fabric may change with storage.5.7 No evidence has been found showing that bendinglength is depend
21、ent on the width. The tendency for specimensto curl or twist will affect the result, because of the rigidityprovided at the edge. Consequently, the wider the strip, the lessimportant is the edge effect.6. Apparatus6.1 Option ACantilever Bending Tester4(Fig. 1).6.1.1 Horizontal Platform, with a minim
22、um area of 38 by200 mm (1.5 by 8 in.) and having a smooth low-friction, flatsurface such as polished metal or plastic. A leveling bubbleshall be incorporated in the platform.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 Movabl
23、e Slide, consisting of a metal bar not lessthan 25 by 200 mm (1 by 8 in.) by approximately 3 mm (18 in.)thick and having a mass of 270 6 5 g (0.6 6 0.01 lb).6.1.1.3 Scale and Reference Point, to measure the length ofthe overhang.6.1.1.4 Specimen Feed Unit, motorized4(see Fig. 1) set to120 mm/min (4.
24、75 in./min) 65 %, or manual equivalent.6.1.2 Cutting Die25 6 1mmby2006 1mm(16 0.04in. by 8 6 0.04 in.).6.2 Option BHeart Loop Tester.6.2.1 Clamp and Stand, for hanging the specimen.6.2.2 Scale, suitably mounted on the stand for measuring thelength of the specimen loop and calibrated either in cm (in
25、.) ordirectly in bending length.NOTE 1If a constant strip length is adopted, the scale may becalibrated to read directly in units of bending length.6.2.3 Brass Bars, two, 25 75 3 6 0.1 mm(130.1256 0.005 in.).6.2.4 Pressure Sensitive Tape.6.2.5 Jig, constructed to allow positioning of the two barswit
26、h their inner edges parallel and at a distance from each otherequal to 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 directedin an applicable material specification or other agreeme
27、ntbetween the purchaser and the supplier. Consider the rolls orpieces of fabric to be the primary sampling units. In theabsence of such an agreement, take the number of fabric rollsspecified in Table 1.NOTE 2An adequate specification or other agreement between thepurchaser and supplier requires taki
28、ng into account the variability betweenrolls or pieces of fabric and between specimens from a swatch from a rollor piece of fabric to provide a sampling plan with a meaningful producersrisk, consumers risk, acceptable quality level, and limiting quality level.7.2 Laboratory SampleFor acceptance test
29、ing, take aswatch extending the width of the fabric and approximately 1m (1 yd) along the machine direction from each roll or piece inthe lot sample. For rolls of fabric, take a sample that willexclude fabric from the outer wrap of the roll or the inner wraparound the core of the roll of fabric, or
30、any end piece.4Apparatus is available commercially.FIG. 1 Example of a Motorized Cantilever Test ApparatusTABLE 1 Number of Rolls, or Pieces, of Fabric in the Lot SampleNumber of Rolls or Piecesin Lot, InclusiveNumber of Rolls or Pieces in Lot Sample1to3 all4to24 425 to 50 5over 50 10 % to a max of
31、10 rolls or piecesD1388 14127.3 Direction of TestConsider the long dimension of thespecimen as the direction of test.7.4 Number of Test SpecimensFrom each laboratory sam-pling unit, take four specimens from the machine direction andfour specimens from the cross-machine direction as applicableto a ma
32、terial specification or contract order.7.5 Cutting Test SpecimensCut the specimens to be usedfor the measurement of machine direction with the longerdimension parallel to the machine direction. Cut the specimensto be used for the measurement of the cross-machine directionwith the longer dimension pa
33、rallel to the cross-machine direc-tion. Label to maintain specimen identity.7.5.1 Take specimens, representing a broad distributionacross the width and length, preferably along the diagonal ofthe laboratory sample, and no nearer the edge than one-tenth itswidth. Ensure specimens are free of folds, c
34、reases, or wrinkles.Avoid getting oil, water, grease, etc. on the specimens whenhandling.7.5.2 Cantilever TestCut test specimens 25 by 200 mm,61mm(1by8in.6 0.04 in.).7.5.3 Heart Loop TestNo standard size for the test speci-men is required. Cut test specimens 50 mm (2 in.) longer thanthe selected str
35、ip length to allow for clamping at the ends. SeeTable 2.7.5.3.1 Select a specimen width at least 25 mm (1 in.) andno more than 75 mm (3 in.) with respect to the tendency of thefabric to curl. For fabrics having a slight tendency to curl, a 256 1mm(16 0.04 in.) wide specimen has been found to besatis
36、factory. As the tendency to curl becomes greater, increasethe width up to a maximum of 75 mm (3 in.).7.5.3.2 Make several trial tests using various strip lengthsselected from Table 2. Select a suitable strip length for acorresponding loop length from Table 2, such that the bendinglength is relativel
37、y independent of strip length.NOTE 3Strip length is the circumferential length of the unclampedportion of the specimen.NOTE 4Specimen strip widths greater than 75 mm (3 in.) have notbeen investigated and are not recommended since reliability of results arequestionable.NOTE 5The bending length using
38、the heart loop option is not entirelyindependent of the strip length. In general, the bending length rises withthe strip length up to a value that remains relatively constant as the striplength is further increased. An additional rise may further be encounteredfor much longer strip lengths. Whenever
39、 possible, compare fabrics in therange 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 horizontalplatform and inclined reference lines. Adjust the platform tohorizontal a
40、s indicated by the leveling bubble.8.1.2 Verify that the bend angle indicator is at the 0.724 rad(41.5) angle marked on the scale.9. Conditioning9.1 Precondition the specimens by bringing them to ap-proximate moisture equilibrium in the standard atmosphere forpreconditioning textiles as directed in
41、Practice D1776, unlessotherwise directed in a material specification or contract order.9.2 After preconditioning, bring the test specimens to mois-ture equilibrium for testing in the standard atmosphere fortesting textiles as directed in Practice D1776 or, if applicable,in the specified atmosphere i
42、n which the testing is to beperformed, unless otherwise directed in a material specificationor contract order.10. Procedure10.1 Test the conditioned specimens in the standard atmo-sphere for testing textiles, which is 21 6 1C (70 6 2F) and65 6 2 % relative humidity, unless otherwise directed in amat
43、erial specification or contract order.10.2 Option ACantilever Test:10.2.1 Remove the movable slide. Place the specimen onthe horizontal platform with the length of the specimen parallelto the platform edge. Align the edge of the specimen with theline scribed on the right-hand edge of the horizontal
44、platform.NOTE 6When known, place the specimen face-side up.10.2.2 Place the movable slide on the specimen, beingcareful not to change its initial position.10.2.3 For automatic testers, turn the tester switch on andwatch the leading edge of the specimen closely. Turn theswitch off the instant the edg
45、e of the specimen touches theknife edge.10.2.4 For manual testers, move the clamped specimen byhand in a smooth manner at approximately 120 mm/min (4.75in./min)6 5 % until the edge of the specimen touches the knifeedge.10.2.5 Read and record the overhang length from the linearscale to the nearest 0.
46、1 cm (0.1 in.).NOTE 7If the specimen has a tendency to twist, take the referencepoint at the center of the leading edge. Do not measure specimens thattwist more than 0.785 rad (45).TABLE 2 Table of Bending LengthsLoop Length,cmBending Length, cm15-cm StripLength20-cm StripLength25-cm StripLength4.0
47、2.19 . .4.2 2.07 . .4.4 1.99 . .4.6 1.86 3.44 5.434.8 1.76 3.30 5.165.0 1.65 3.17 4.915.2 1.56 3.03 4.715.4 1.45 2.90 4.535.6 1.35 2.80 4.365.8 1.25 2.67 4.206.0 1.14 2.57 4.066.2 1.04 2.47 3.926.4 0.93 2.37 3.806.6 0.81 2.26 3.676.8 0.69 2.16 3.567.0 0.53 2.06 3.457.2 . 1.96 3.347.4 . 1.86 3.217.6
48、. 1.76 3.127.8 . 1.66 3.028.0 . . 2.918.2 . . 2.828.4 . . 2.72D1388 141310.2.6 Test the face and back of both ends of each specimenfor 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 ahorizontal surface such that the inner edges
49、 are separated by adistance equal to the selected strip length (see 6.2.5).10.3.2 Lay the test specimen across the two bars with theouter edge approximately 5 6 1 mm (0.5 6 0.005 in.) from oneend of each bar.10.3.3 Attach one end of the specimen strip to one bar usingpressure-sensitive tape, being careful to align to one edge ofthe bar. Apply just enough tension to the specimen to hold ittaut, but without stretching, and attach the other specimen endto the second bar in a similar manner.10.3.3.1 A suitable procedure for mounting and mea
