1、Designation: D1388 18Standard 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 indicat
2、es 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 stiffnessproperties of fabrics. Ben
3、ding 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 under its own mass.1.1.2 Option BHeart Loop Test, employing the principleof a loop formed in a fabric strip and hung verti
4、cally.1.2 This test method applies to most fabrics includingwoven fabrics, air bag fabrics, blankets, napped fabrics, knittedfabrics, layered fabrics, pile fabrics. The fabrics may beuntreated, heavily sized, coated, resin-treated, or otherwisetreated.1.3 The values stated in SI units are to be rega
5、rded 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 theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and de
6、ter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mend
7、ations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD2904 Practice for Interlaboratory Testing of a Textile TestMethod that Produce
8、s Normally Distributed Data (With-drawn 2008)3D2906 Practice for Statements on Precision and Bias forTextiles (Withdrawn 2008)3D3776 Test Methods for Mass Per Unit Area (Weight) ofFabricD4850 Terminology Relating to Fabrics and Fabric TestMethods3. Terminology3.1 For all terminology relating to D13.
9、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, stiffness.3.2 For all other terminology related to textiles, refer toTerminology D123.4. S
10、ummary 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 length of the overhang is measured when the tip of thespecimen is depressed under it
11、s 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.4.2 Option B, Heart Loop TestA strip of fabric is formedinto a heart-shaped loop. Th
12、e 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 test method are consideredsatisfactory for acceptance testing of commercial shipment
13、s1This 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, 2018. Published October 2018. Originallyapproved in 1956. Last previous edition approved in 2014 as D1
14、388141. DOI:10.1520/D1388-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of th
15、is historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in th
16、e Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1since current estimates of between-laboratory precision areacceptable and the method is used extensively in the trade
17、 foracceptance testing.5.1.1 In case of a dispute arising from differences inreported test results when using this test method for acceptancetesting of commercial shipments, the purchaser and the sup-plier should conduct comparative tests to determine if there isa statistical bias between their labo
18、ratories. 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 possible and that arefrom a lot of material of the type in question. Test specimensshould then be randomly assigned i
19、n equal numbers to eachlaboratory for testing. The average results from the twolaboratories should be compared using the appropriate statis-tical analysis and an acceptable probability level chosen by thetwo parties before testing is begun. If a bias is found, either itscause must be found and corre
20、cted 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 testingwoven fabrics than knit fabrics.5.3 The Cantilever Test Option is the preferred procedurebecause it is simpler to perf
21、orm. 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 thatshow a tendency to curl or twist.5.5 Both options can provide a correlation with a subjectiveevaluation of a given fabr
22、ic 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 dependent on the width. The tendency for specimensto curl or twist will affect the result, because of the rigidityprovided a
23、t 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 minimum area of 38 by200 mm (1.5 by 8 in.) and having a smooth low-friction, flatsurface such as polished metal or plastic.
24、 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 Movable Slide, consisting of a metal bar not lessthan 25 by 200 mm (1 by 8 in.) by approximately 3 mm (18 in.)thick and havi
25、ng 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 (4.75 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 BHea
26、rt 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.) ordirectly in bending length.NOTE 1If a constant strip length is adopted, the scale may becalibrated to read direct
27、ly 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 barswith their inner edges parallel and at a distance from each otherequal to the selected strip length (see Fig. 2).7. Sampl
28、ing 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 agreementbetween the purchaser and the supplier. Consider the rolls or4Apparatus is available commercially.FIG.
29、1 Example of a Motorized Cantilever Test ApparatusFIG. 2 Example of a Heart Loop TesterD1388 182pieces 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 thepur
30、chaser and supplier requires taking 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 Lab
31、oratory SampleFor acceptance testing, 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 th
32、e core of the roll of fabric, or any end piece.7.3 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 a
33、s applicableto a material 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
34、longer dimension parallel 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 a
35、re free of folds, creases, 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 t
36、hanthe selected strip 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 be
37、en found to besatisfactory. 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 bending
38、length is relatively 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 be
39、nding length using 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 stri
40、p lengths. Whenever 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 plat
41、form tohorizontal as 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 texti
42、les as directed in 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 spe
43、cified atmosphere in 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 otherwi
44、se directed in amaterial specification or contract order.TABLE 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 10 rolls or piecesTABLE 2 Table of Bending Length
45、sLoop Length,cmBending Length, cm15-cm StripLength20-cm StripLength25-cm StripLength4.0 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 3.80
46、6.6 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 . 1.76 3.127.8 . 1.66 3.028.0 . . 2.918.2 . . 2.828.4 . . 2.72D1388 18310.2 Option ACantilever Test:10.2.1 Remove the movable slide. Place the specimen onthe horizontal platform with the length of the specimen pa
47、rallelto the platform edge. Align the edge of the specimen with theline 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 specimen, beingcareful not to change its initial position.10.2.3 For automatic tes
48、ters, turn the tester switch on andwatch the leading edge of the specimen closely. Turn theswitch off the instant the edge 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 edg
49、e of the specimen touches the knifeedge.10.2.5 Read and record the overhang length from the linearscale to the nearest 0.1 cm (0.1 in.) (see Fig. 3).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).10.2.6 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 are
