1、Designation: D6588/D6588M 11Standard Test Method forFatigue of Tire Cords (Disc Fatigue Test)1This standard is issued under the fixed designation D6588/D6588M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of fatigue oftire cords in rubber due to compression or extension, or both,using a disc
3、 fatigue tester. The fatigue is measured as a loss instrength.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combining
4、values from the two systems may result in non-conformancewith the standard.1.3 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 and health practices to determine
5、 the applicabilityof regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD885 Test Methods for Tire Cords, Tire Cord Fabrics, andIndustrial Filament Yarns Made from Manufactured
6、Organic-Base FibersD1776 Practice for Conditioning and Testing TextilesD6477 Terminology Relating to Tire Cord, Bead Wire,Hose Reinforcing Wire, and FabricsD7269 Test Methods for Tensile Testing of Aramid Yarns3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to tire cord andfabr
7、ics, see Terminology D6477.3.1.2 For definitions of other terms related to textiles, seeTerminology D123.4. Summary of Test Method4.1 disc fatigue is a measure of the strength loss of a tirecord, which is subjected to repeated stresses. The stresses areaccomplished by subjecting the tire cords, afte
8、r being cured inrubber, to repeated cycles of compression and extension.4.2 The specimen of interest is the cord after it has beenstressed and later removed from the rubber in which it wasimbedded. Cord specimens are placed between strips of rubbercompound and molded into blocks. The specimen block
9、is thenmounted between two rotating discs that are positioned in sucha way that the specimen will undergo compression or exten-sion, or both, as the discs rotate. After a specified number ofcycles, the cords are removed from the blocks and theirbreaking force measured on a tensile testing machine. T
10、hefatigue, based on the unfatigued specimen strength, is ex-pressed as a percent strength loss in fatigued specimens.5. Significance and Use5.1 This test method is not recommended for acceptancetesting of commercial shipments in the absence of reliableinformation on between-laboratory precision.5.1.
11、1 If there are differences of practical significance be-tween the reported test results for two laboratories (or more), acomparative test should be performed to determine if there is astatistical bias between them, using competent statistical assis-tance. As a minimum, test samples should be used th
12、at are ashomogeneous as possible, that are drawn from a material fromwhich the disparate test results were obtained, and that arerandomly assigned in equal numbers to each laboratory fortesting. Other fabrics with established test values may be usedfor this purpose. The test results from the two lab
13、oratoriesshould be compared using a statistical test for unpaired data, ata probability level chosen prior to the testing series. If a bias isfound, either its cause must be found and corrected, or futuretest results must be adjusted in consideration of the knownbias.1This test method is under the j
14、urisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.19 on Industrial Fibers andMetallic ReinforcementsCurrent edition approved Jan. 1, 2011. Published January 2011. Originallyapproved in 2000. Last previous edition approved in 2010 as D658810a. DOI:10.15
15、20/D6588_D6588M-11.2For 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.1Copyright ASTM International, 100 Barr Ha
16、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus, Materials, and Reagents6.1 Disc Fatigue Tester (see schematic drawing in Fig. 1),with capacity for 12 specimens. For actual dimensions, seepatent US 2595069. Testers with different capacity are accept-able.6.2 Dis
17、placement Transducer, with digital readout or dialgage for setting distance between disc fatigue flanges to thenearest 0.01 mm 0.004 in.6.3 Mold, top and bottom sections with cavities in each for12 or 24 specimens with the dimensions of 10.8 by 12.7 by76.2 mm 716 by12 by 3 in. (See schematic drawing
18、 in Fig.2). All dimensions given require an accuracy of 0.1 mm 0.04in. The top of the mold may be coated with TFE-fluorocarbonto release the specimens easily. Molds with other numbers ofcavities may be used.6.4 Weights, having a mass of 50 6 5gor1006 10 g, orboth, for tensioning yarns or cords while
19、 building specimenblocks.6.5 Curing press, capable of maintaining a minimum pres-sure of 3.5 MPa 500 psi over the total area of the moldsurface, and capable of a platen temperature control within63C 65F of the temperature specified for curing therubber compound.6.6 Guillotine, Hand-operated, capable
20、 of slicing thesample blocks (see 11.2.2).6.7 Tensile Testing Machine, CRE type, in accordance withSpecification D76.6.8 Clamps, air-actuated, flat, rubber-faced or bollard-type.6.9 Rubber Compound, with a thickness of 6.0 6 0.3 mm0.24 6 0.01 in., rolled up in polyethylene liner and free frommoistur
21、e and contamination.NOTE 1The rubber type used, especially rubber modulus, will affectthe results.6.10 Gloves, neoprene or other solvent-resistant rubber.6.11 Solvent, 1.1.2.2 tetrachloroethylene, CHCl2CHCl2or1.1.1 trichloroethane CCl3CH3) for removing cords fromrubber.6.12 Tachometer or Stroboscope
22、.6.13 Screwdriver, or other tightening device.7. Hazards7.1 The manufacturers material data sheets (MSDSs) shallbe used to obtain information on handling, storage, use, anddisposal of chemicals used in this test method.8. Sampling and Test Specimens8.1 Primary Sampling UnitConsider one roll of dippe
23、dtire cord fabric or a cord package as the primary sampling unit.8.2 Laboratory Sampling UnitAs a laboratory samplingunit, from each primary sampling unit prepare tabby samplesby taking a sample equal to the length of cord between theregular tabby woven at the end of the roll and a special tabbywove
24、n a short distance from the end when the roll of fabric ismanufactured. For rolls that do not have a special woven tabby,improvise a tabby by the use of gummed tape or strips ofcemented fabric applied across a section of the cord fabric togive a tabby sample length at least 0.5 m 18 in. long and atl
25、east one tenth of the roll width wide.8.2.1 Preparation of Tabby SamplesThe handling of thesamples must be done with care. The person obtaining thesample should wear clean gloves. Cut the warp cords of thedipped fabric along the centerline of the special tabby for adistance equal to the width of the
26、 sample. If this distance is lessthan the full width of the fabric, cut the filling yarns of thesample and of the special and regular tabbies in the directionparallel with the warp cords. The resulting section of cordfabric is the tabby sample. Attach the tabby sample to a pieceof cardboard or fiber
27、board, the length of which shall be equalto at least the length of the cord warp between tabbies. Fold thetabby portions of the sample over each end of the board, andsecure the sample to the board with pressure-sensitive tape orstaples. Use care to avoid contact of tape or staples with thearea to be
28、 tested. Handle the sample carefully. Discard anyspecimen subjected to any bend with a diameter less than tentimes the yarn/cord thickness (or diameter). The board with theFIG. 1 Schematic Top View of the Disc Fatigue Tester with Two SpecimensD6588/D6588M 112sample may be folded lengthwise and paral
29、lel with the warp forconvenience. Place the board with the fabric sample in a blackpolyethylene bag, or wrap it with several layers of blackpolyethylene film to protect the sample from ultraviolet (UV)and ozone.8.3 Test Specimens:8.3.1 Specimens Yarns or CordFrom the laboratorysample, take the numbe
30、r of specimens needed for each block,multiplied by the number of blocks that have to be built asshown in Table 1. For Nylon, Polyester, and Rayon, take aduplicate number of specimens for unfatigued control testing.For Aramids, the unfatigued control testing is done on thelaboratory sample.8.3.2 Numb
31、er of Blocks for Fatigue and Control TestingPrepare the number of blocks to be fatigue tested as shown inTable 1. For Nylon, Polyester, and Rayon, take a duplicatednumber of blocks for unfatigued control testing. For Aramids,the unfatigued control testing is done on the laboratory sample.8.3.3 Label
32、 both yarn/cord specimens and block specimensto maintain specimen identity.8.4 Building Test Specimen BlocksPrepare test specimenblocks in accordance with the directions in 8.4.1 through 8.4.58.4.1 Cut a piece of rubber stock large enough to cut twostrips of 6.0 6 0.3 mm 0.24 6 0.01 in. for each cav
33、ity in themold. Cut sufficient number of strips of the rubber stock.Remove polyethylene backing from one side of rubber stripsjust prior to using. Place a strip in each of the cavities of thetwo halves of the mold with the polyethylene side up. Press theFIG. 2 Schematic View of the MoldTABLE 1 Numbe
34、r of Specimens (Cords) per BlockMaterial Nominal LinearDensity, DtexNumber ofSpecimens (Cords)per BlockNumberof BlocksNylon #220022005333Polyester #220022005333Rayon all 1 6Aramid all 1 6Twisted yarn ofany materialall 1 6D6588/D6588M 113rubber firmly into the cavities. A cold press may be used.Remov
35、e the polyethylene backing from the top of the rubber,leaving the rubber surface free of contamination and finger-prints.8.4.2 For packages, discard the outer layer of cord. Cutapproximately1m1ydofdipped cord. Simultaneously loadtwo adjacent cavities in the bottom mold by one end of a singlecord at
36、the first clamp. Position the cord in the center of the firstcavity, loop it through the second clamp at the end of the mold(hang a tensioning mass on the loop to ease loading) then downthe center of the second cavity and back through the firstclamp. Tighten the first clamp on the two cord ends. Ten
37、sioneach cord with a tensioning mass of 50 g by hanging 100 g onthe loop end. Examine rear and front cord slots to be certainthat all cords are properly aligned. Adjust cords as necessarythen hold in position with masking tape at the ends of eachblock. Once the cords have been tensioned and aligned,
38、 closethe second clamp and remove the mass. Put an identificationtag on the ends of each cord. Continue filling the remainingcavities in the bottom of the mold (see schematic drawing inFig. 2). Place top half of the mold on the bottom half.8.4.3 Place the mold assembly in the press, preheated to the
39、specified temperature and apply a minimum pressure of 3.5MPa 500 psi over the total area of the mold surface.Vulcanize for the specified time at the temperature.8.4.4 Reduce the pressure and remove the mold.8.4.5 Open the mold and remove the specimen blocks. Markeach block with identification. Trim
40、the rubber overflow andcut the cords so that the total length in rubber and lengthextending on each side will be not less than 150 mm 6 in.Condition the specimen blocks for at least 16 h at ambientroom temperature9. Preparation of Apparatus9.1 Disc Fatigue Tester:9.1.1 Set disc in the tester paralle
41、l and 25.40 6 0.02 mm 16 0.001 in. apart. Do this by setting the angle of the right discat 0 rad 0 and adjusting the left disc to the proper distance.9.1.2 Set the tester for compression and extension condi-tions using Table 2 orEq1orEq2.M 5 DOE2C!/2 (1)Dt5 DO1 M (2)where:M = change of the original
42、distance, mm in., if M isnegative, the distance is decreased by that amountand if M is positive, the distance is increased,DO= original distance, (25.4 mm) 1 in.,Dt= parallel testing distance of the discs,E = percent elongation/100, andC = percent compression/100.9.1.3 Make the appropriate M change
43、in the distance be-tween each pair of discs by moving the left disc in a straightline toward, or away from, the right disc until the specifiedparallel distance between the two discs has been achieved.9.1.4 Next, set the left disc to the required compression andextension settings as obtained from Tab
44、le 2,Eq1,Eq2orbychanging the angle of the left disc. Read (and record) themaximum and minimum distances between the discs.9.2 Tensile Testing Machine Setup:9.2.1 Set the gage length at 30 mm 1.2 in., except foraramid where a gage length of 250 mm 10.0 in. is required.9.2.2 For nylon, polyester, and
45、rayon, use flat or bollard typeclamps and set the crosshead speed at 100 % of the gage lengthper minute (Test Methods D885). For aramid, use suitablebollard type clamps and set the crosshead speed at 50 % of thegage length per minute (Test Methods D7269).10. Conditioning10.1 Rubber compound properti
46、es are best maintained bystorage in a cool, dry atmosphere. Excessive rubber compoundmoisture may lower adhesion of some fiber/rubber composites.10.2 Store samples (tabbies) or adhesive-treated cord inmoisture-proof, UV, and ozone protective bags (aluminum-coated or black polythene bags may be suffi
47、cient) at tempera-tures below 24C 75F.10.3 Condition fatigued cords and non-fatigued controlcords for at least 16 h in the standard atmosphere for testingtextiles, as described for tire cords (see Practice D1776) priorto determining breaking force.11. Procedure11.1 Flexing Specimen Blocks:11.1.1 Det
48、ermine the 25.4-mm 1.0-in. position (loadingposition) for the discs and load the specimens (blocks) in thisposition. Distribute blocks of one sample evenly between bothends of the testing device. Place the specimens in slots in theTABLE 2 Values for Compression and Elongation of the Different CordsF
49、iber Compression C, (%) Elongation E, (%) Compression, (mmin.)Extension, (mm in.) Correction M, (mmin.)Parallel, Dt(mm in.)Nylon 12.5 6.3 3.18 0.875 1.60 1.063 .79 0.031 24.61 0.969Polyester 12.5 6.3 3.18 0.875 1.60 1.063 .79 .031 24.61 0.969Rayon 12.5 6.3 3.18 0.875 1.60 1.063 .79 .031 24.61 0.969Aramid 14 2 3.56 0.86 .51 1.020 1.52 .06 23.88 0.940Twisted yarn of anymaterial6 2 1.52 0.940 .51 1.060 .51 .02 24.89 0.980D6588/D6588M 114discs and slip ends of cords un
