1、Designation: D 6588 02Standard Test Method forFatigue of Tire Cords (Disc Fatigue Test)1This standard is issued under the fixed designation D 6588; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 fatigue te
3、ster. The fatigue is measured as a loss instrength.1.2 The values stated in either SI units or other units (inparentheses) are to be regarded separately as standard. Thevalues stated in each system are not exact equivalents; there-fore, each system shall be used independently of the other.1.3 This s
4、tandard 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 the applicabilityof regulatory limitations prior to use.2. Referenced Documents2.1 A
5、STM Standards:D 76 Specification for Tensile Testing Machines for Tex-tiles2D 123 Terminology Relating to Textiles2D 885 Methods of Testing Tire Cords, Tire Cord Fabrics,and Industrial Filament Yarns Made from Man-MadeOrganic-Base Fibers2D 1776 Practice for Conditioning Textiles for Testing2D 6477 T
6、erminology Relating to Tire Cord and Fabrics3. Terminology3.1 Definitions:3.1.1 For definitions of terms relating to tire cord andfabrics, see Terminology D 6477.3.1.2 For definitions of other terms related to textiles, seeTerminology D 123.4. Summary of Test Method4.1 disc fatigue is a measure of t
7、he strength loss of a tirecord, which is subjected to repeated stresses. The stresses areaccomplished by subjecting 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 th
8、e rubber in which it wasimbedded. Cord specimens are placed between strips of rubbercompound and molded into 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. A
9、fter a specified number ofcycles, the cords are removed from the blocks and theirbreaking force measured on 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
10、not recommended for acceptancetesting of commercial shipments in the absence of reliableinformation on between-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 det
11、ermine if there is astatistical bias between them, using competent statistical assis-tance. As a minimum, 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
12、to each laboratory fortesting. Other fabrics with established test values may be usedfor this purpose. The 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 isfound, either its caus
13、e must be found and corrected, 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 c
14、apacity are accept-able.6.2 Transducer, with digital readout or dial gage for settingdistance between disc fatigue flanges to the nearest 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 (716by12 by 3 in.).
15、 (See schematic drawing in Fig. 2).All dimensions given require an accuracy of 0.1 mm (0.04 in.).1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.19 on Tire Cord and FabricsCurrent edition approved April 10, 2002. Publi
16、shed June 2002. Originallypublished as D658800. Last previous edition D658800.2Annual Book of ASTM Standards, Vol 07.01.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.The top of the mold may be coated with TFE-fluorocarbon torelease
17、 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 specimenblocks.6.5 Curing press, capable of maintaining a minimum pres-sure of 3.5 MPa (500 psi) over the total area of the mo
18、ldsurface, 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 thesample blocks (see 11.2.2).6.7 Tensile Testing Machine, CRE type, in accordance withSpecification D 76.6.8 Clamps, ai
19、r-actuated, flat, rubber-faced or bollard-type.6.9 Rubber Compound, with a thickness of 6.0 6 0.3 mm(0.24 6 0.01 in.), rolled up in polyethylene liner and free frommoisture and contamination.NOTE 1The rubber type used, especially rubber modulus, will affectthe results.6.10 Gloves, neoprene or other
20、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 Screwdriver, or other tightening device.7. Hazards7.1 The manufacturers material data sheets (MSDSs) shallbe used to obtain i
21、nformation 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 fabric or a cord package as the primary sampling unit.8.2 Laboratory Sampling UnitAs a laboratory samplingunit, from eac
22、h 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 distance from the end when the roll of fabric ismanufactured. For rolls that do not have a special woven tabby,improvise
23、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 of the roll width wide.8.2.1 Preparation of Tabby SamplesThe handling of thesamples must be done with care. The pe
24、rson 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 distance is lessthan the full width of the fabric, cut the filling yarns of thesample and of the special and reg
25、ular 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 length of which shall be equalto at least the length of the cord warp between tabbies. Fold thetabby portions of the s
26、ample 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 tested. Handle the sample carefully. Discard anyspecimen subjected to any bend with a diameter less than 10times the yarn/cord t
27、hickness (or diameter). The board with thesample may be folded lengthwise and parallel 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 Te
28、st Specimens:8.3.1 Specimens Yarns or CordFrom the laboratorysample, take the number of specimens needed 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 a
29、nd Control TestingPrepare the number of blocks to be fatigue tested as shown inFIG. 1 Schematic Top View of the Disc Fatigue Tester with Two SpecimensD6588022Table 1. Prepare a duplicated number of blocks for unfatiguedcontrol testing. The number of blocks specified is the minimumneeded to constitut
30、e 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 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
31、.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 backing from one side of rubber stripsjust prior to using. Place a strip in each of the cavities of thetwo halves of the mo
32、ld with the polyethylene side up. Press therubber firmly into the cavities. A cold press may be used.Remove 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. Cutapproximately1m(1
33、yd)ofdipped 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 second clamp at the end of the mold(hang a tensioning mass on the loop to ease loading) then downthe ce
34、nter 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 are loaded in the same manner asa single cord, however, they are loaded and clamped simulta-neously
35、. Tension each cord with a tensioning mass of 50 g byhanging 100 g on each cord loop. Examine rear and front cordFIG. 2 Schematic View of the MoldTABLE 1 Number of Specimens (Cords) per BlockMaterial Nominal LinearDensity, DtexNumber ofSpecimens (Cords)per BlockNumberof BlocksNylon #220022005333Poly
36、ester #220022005333Rayon all 1 6Aramid all 1 6Twisted yarn ofany materialall 1 6D6588023slots to be certain that all cords are properly aligned. Adjustcords as necessary then hold in position with masking tape atthe ends of each block. Once the cords have been tensioned andaligned, close the second
37、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). Place top half of the mold on the bottomhalf.8.4.3 Place the mold assembly in the press, preheated to thespecified temperat
38、ure 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 the rubber overf
39、low 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 parallel and 25.40 6
40、 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 or Eq 1 or Eq 2.M 5 DOE2C!/2 (1)Dt5 DO1 M (2)where:M = change of the original dist
41、ance, 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
42、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
43、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,
44、 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 % of the gage lengthper minute.10. Conditioning10.1 Rubber compound properties are best maintained b
45、ystorage 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 sufficient) at tempera-tures
46、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 D 1776) priorto determining breaking force.11. Procedure11.1 Flexing Specimen Blocks:11.1.1 Determine the 25.4-mm (1
47、.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 ends tobecome damaged during tester operation. Screw the holdingclamps on top of the block ends
48、 in each disc and tighten withair driven screwdriver or other tightening device.NOTE 2If the blocks are loaded position, the elongation and compres-sion will be different from the calculated values.11.1.2 Adjust the tester to run at a speed of 2 300 to 2 700rpm (3 600 000 cycles/24 h per 24 h) using
49、 a tachometer. Otherspeeds in the range of 2 300 to 2 700 can be selected. Run thetester for the desired time (see Note 3).NOTE 3Usual running times are 6, 24, 48, and 72 h. The strength lossis not linear with the running time. Retained strength values between 90and 40 % are recommended.11.1.3 Stop the tester at the completion of flexing timerequired and promptly remove the specimen blocks (see Note4).NOTE 4The clamps can be removed while in the top position and thesamples pulled from the front position. Pull one end of sample at a timefrom slots.11.2 Cord Preparatio
