ASTM D6588 D6588M-2010 9375 Standard Test Method for Fatigue of Tire Cords (Disc Fatigue Test).pdf

1、Designation: D6588/D6588M 10Standard 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 Fabrics3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to tire cord andfabrics, see Terminology D6477.3.1.1.1 The following terms

7、 are relevant to this standard:cord, tire, and tire cord.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 s

8、ubjecting the tire cords, after 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 in

9、to blocks. The specimen block 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 o

10、n a tensile testing machine. Thefatigue, 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 bet

11、ween-laboratory precision.5.1.1 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,

12、test samples should be used that 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

13、 test results from the two laboratoriesshould be compared using a statistical test for unpaired data, ata probability level chosen prior to the testing series. If a bias is1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D1

14、3.19 on Tire Cord and FabricsCurrent edition approved Jan. 1, 2010. Published January 2010. Originallyapproved in 2000. Last previous edition approved in 2002 as D6588 02. DOI:10.1520/D6588-02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se

15、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.found, either its cause must be found and corrected,

16、or futuretest results must be adjusted in consideration of the knownbias.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 Tra

17、nsducer, with digital readout or dial gage for settingdistance between disc fatigue flanges to the nearest 0.01 mm0.004 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 in Fig.2). A

18、ll 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 building spe

19、cimenblocks.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 of slicing t

20、hesample 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 frommoisture and contami

21、nation.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 Strobotac.6.13 Screwdrive

22、r, 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 dippedtire cord fabri

23、c 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 tabbywoven a short distan

24、ce 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 atleast one tenth o

25、f 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 sample. If this

26、 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 fiberboard, the lengt

27、h 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 theFIG. 1 Schematic Top View

28、of the Disc Fatigue Tester with Two SpecimensD6588/D6588M 102area to be tested. Handle the sample carefully. Discard anyspecimen subjected to any bend with a diameter less than 10times the yarn/cord thickness (or diameter). The board with thesample may be folded lengthwise and parallel with the warp

29、 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 (UVand ozone.8.3 Test Specimens:8.3.1 Specimens Yarns or CordFrom the laboratorysample, take the number of specimens nee

30、ded for each block,multiplied by the number of blocks that have to be built asshown in Table 1. Take a duplicate number of specimens forunfatigued control testing.8.3.2 Number of Blocks for Fatigue and Control TestingPrepare the number of blocks to be fatigue tested as shown inTable 1. Prepare a dup

31、licated number of blocks for unfatiguedcontrol testing. The number of blocks specified is the minimumneeded to constitute a valid test.8.3.3 Label both yarn/cord specimens and block specimensto maintain specimen identity.8.4 Building Test Specimen BlocksPrepare test specimenblocks in accordance with

32、 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 cavity in themold. Cut sufficient number of strips with the long directionparallel to the calendering direction of the rubber stock.Remove polyethylene backi

33、ng 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 therubber firmly into the cavities. A cold press may be used.FIG. 2 Schematic View of the MoldTABLE 1 Number of Specimens (Cords) per BlockMat

34、erial Nominal LinearDensity, DtexNumber ofSpecimens (Cords)per BlockNumberof BlocksNylon #220022005333Polyester #220022005333Rayon all 1 6Aramid all 1 6Twisted yarn ofany materialall 1 6D6588/D6588M 103Remove the polyethylene backing from the top of the rubber,leaving the rubber surface free of cont

35、amination 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 the first clamp. Position the cord in the center of the firstcavity, loop it through the seco

36、nd 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. Tensioneach cord with a tensioning mass of 50 g by hanging 100 g onthe loop end. Multiple cords

37、are loaded in the same manner asa single cord, however, they are loaded and clamped simulta-neously. Tension each cord with a tensioning mass of 50 g byhanging 100 g on each cord loop. Examine rear and front cordslots to be certain that all cords are properly aligned. Adjustcords as necessary then h

38、old in position with masking tape atthe ends of each block. Once the cords have been tensioned andaligned, close the second clamp and remove the mass. Put anidentification tag on the ends of each cord. Continue filling theremaining cavities in the bottom of the mold (see schematicdrawing in Fig. 2).

39、 Place top half of the mold on the bottomhalf.8.4.3 Place the mold assembly in the press, preheated to thespecified 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 rem

40、ove the mold.8.4.5 Open the mold and remove the specimen blocks. Markeach block with identification. Trim 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 ambi

41、entroom temperature9. Preparation of Apparatus9.1 Disc Fatigue Tester:9.1.1 Set disc in the tester parallel 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 ext

42、ension condi-tions using Table 2 orEq1orEq2.M 5 DOE2C!/2 (1)Dt5 DO1 M (2)where:M = change of the original 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 t

43、he discs,E = percent elongation/100, andC = percent compression/100.9.1.3 Make the appropriate M change 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 achie

44、ved.9.1.4 Next, set the left disc to the required compression andextension settings as obtained from Table 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

45、in., except foraramid where a gage length of 250 mm (10.0 in. is required.9.2.2 For nylon, polyester, and rayon, use flat or bollard typeclamps and set the crosshead speed at 100 or 50 % of the gagelength per minute. For aramid, use suitable bollard type clampsand set the crosshead speed at 50 or 25

46、 % of the gage lengthper minute.10. Conditioning10.1 Rubber compound properties 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, an

47、d ozone protective bags (aluminum-coated or black polythene bags may be sufficient) 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 de

48、termining breaking force.11. Procedure11.1 Flexing Specimen Blocks:11.1.1 Determine the 25.4-mm 1.0-in. position (loadingposition) for the discs and load the specimens blocks) in thisposition. Place the specimens in slots in the discs and slip endsof cords under the disc enclosure. Do not allow the

49、ends tobecome damaged during tester operation. Screw the holdingclamps on top of the block ends in each disc and tighten withair driven screwdriver or other tightening device.TABLE 2 Common Values for Compression and Elongation of the Different CordsFiber Compression C, (%) Elongation E, (%) Compression, mm(in.)Extension, mm (in.) Correction M, mm(in.)Parallel, Dtmm (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 0.969R