1、Designation: D430 06 (Reapproved 2012)Standard Test Methods forRubber DeteriorationDynamic Fatigue1This standard is issued under the fixed designation D430; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates 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 Department of Defense.1. Scope1.1 These test methods cover testing procedures that es
3、ti-mate the ability of soft rubber materials to resist dynamicfatigue. No exact correlation between these test results andservice is given or implied. This is due to the varied nature ofservice conditions. These test procedures do yield data that canbe used for the comparative evaluation of rubber o
4、r compositerubber-fabric materials for their ability to resist dynamicfatigue.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with
5、its use. It is theresponsibility 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:2D412 Test Methods for Vulcanized Rubber and Thermo-plastic Elastomers
6、TensionD1349 Practice for RubberStandard Temperatures forTestingD1682 Standard Methods of Test for Breaking Load andElongation of Textile Fabrics3D3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD3767 Practice for RubberMeasurement of DimensionsD4483 Practice for Evaluati
7、ng Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3. Summary of Test Methods3.1 Three test methods are covered, using the followingdifferent types of apparatus:3.1.1 Method AScott Flexing Machine.3.1.2 Method BDeMattia Flexing Machine.3.1.3 Method CE. I. DuP
8、ont de Nemours and Co. FlexingMachine.3.1.4 The Scott flexing machine is used principally for testsof Type I, the DeMattia flexing machine for tests of Type II,while the DuPont apparatus is adapted to tests of either Type Ior II, refer to 4.2.4. Significance and Use4.1 Tests for dynamic fatigue are
9、designed to simulate thecontinually repeated distortions received in service by manyrubber articles, such as tires, belts, footwear, and moldedgoods.4.1.1 These distortions may be produced by extension,compressive, and bending forces or combinations thereof.4.1.2 The effect of the distortions is to
10、weaken the rubberuntil surface cracking or rupture occurs. Where rubber iscombined with other flexible materials such as fabric, the effectmay be evidenced by separation at the interface between thematerials, caused either by breaking of the rubber or failure ofthe adhesion or both.4.2 These tests a
11、re, therefore, of the following two types:4.2.1 Type ITests designed to produce separation ofrubber-fabric combinations by controlled bending of the speci-mens.4.2.2 Type IITests designed to produce cracking on thesurface of rubber by either repeated bending or extension asmay occur in service.5. Ap
12、plication5.1 Established specifications, practices or methods of testas agreed upon between customer and supplier take precedenceover those contained herein.1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.15 on Degra
13、dationTests.Current edition approved May 1, 2012. Published May 2012. Originallyapproved in 1935. Last previous edition approved in 2006 as D430 061. DOI:10.1520/D0430-06R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
14、Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
15、28-2959, United States.6. Preparation of Test Specimens6.1 Except as may be otherwise specified herein, specimenpreparation shall comply with the requirements of PracticeD3183.7. Test Temperatures and Conditioning7.1 The standard temperature for testing shall be as de-scribed in Practice D1349 for t
16、he Standard Laboratory Atmo-sphere 23 6 2C (73.4 6 3.6F).7.2 Controlled temperatures outside the standard range areacceptable and often desirable. Notation of nonstandard testtemperatures shall appear in the report.7.3 Specimens shall be conditioned at the specified tempera-ture for no less than 12
17、h prior to testing.METHOD A: SCOTT FLEXING MACHINE48. Type of Strain8.1 The Scott flexing machine test method is used to test forply separation in test specimens composed of plies of fabricbonded to rubber compounds (belts, tires, etc.) by controlledbending.9. Test Specimens from Belts9.1 The specim
18、ens shall be 209.5 mm (8.25 in.) in length by25 6 2mm(16 0.08 in.) in width.9.2 The thickness shall be measured in accordance withPractice D3767, Procedure A, recorded and reported.9.3 Test specimens selected from samples of belts shall becut lengthwise of the belt and their locations recorded andre
19、ported.9.4 The seam area of a folded belt shall not be included inany of the test specimens and the folded edge shall be removedbefore cutting the specimens.9.5 The specimens shall consist of four plies for routinetests, any excess plies being removed by carefully stripping soas not to weaken the re
20、maining bonds.9.5.1 When another number of plies are used in nonroutinetests, the number of plies shall be recorded and reported.10. Test Specimens from Tires10.1 Test specimens from tires shall be cut to the dimen-sions indicated in 10.2.3.1. If suitable test specimens cannot becut from tires it is
21、 necessary to prepare special flexing padsamples as described in 10.2.1-10.2.3 from the cord fabric andrubber compounds that are to be tested.10.2 Specimen thickness measurements shall be determinedin accordance with Practice D3767, Procedure A.10.2.1 Preparing Unvulcanized Flex Specimen Pads:10.2.1
22、.1 Solution coated, frictioned, or bare cord fabric shallbe calendered with the rubber compound to a total thickness of1.25 mm (0.050 in.).10.2.1.2 Six plies of this material shall be assembled usinga hand roller so that the plies run in alternate directions. Thefirst, third, and fifth plies shall h
23、ave the cords lengthwise andthe second, fourth, and sixth plies crosswise of the pad.10.2.1.3 Care shall be taken that the same calendered side ofeach piece is facing up and that each alternate ply crosses atright angles.10.2.1.4 The pad, which shall have a thickness of 7.6 mm(0.300 in.) shall be cu
24、t by means of a template and knife todimensions of 125 3 202 mm (4.94 3 7.94 in.). The long edgeof the template shall be held parallel with the lengthwise cordsin the specimen pad.10.2.2 Vulcanization of Flexing Pad Specimens:10.2.2.1 The specimen pad shall be vulcanized in a steelmold having single
25、, or multiple, cavities measuring 125 3 2033 8.25 mm (5 3 8 3 0.325 in.).10.2.2.2 Uniform compression shall be applied over theentire top surface of the specimen pad. This compression,together with slight stretching produced by the unvulcanizedpad being cut slightly smaller than the cavity, ensures
26、straightcords in the cured specimen pad.10.2.2.3 In order to obtain uniform compression, it isnecessary to make up the difference between the specimen padthickness and the mold depth by means of filler layers ofHolland cloth or aluminum foil placed on top of the specimenpad.10.2.2.4 These filler lay
27、ers shall be added until the totalthickness of the assembly is 7.75 mm (0.305 in.).10.2.2.5 A sheet of rubber compound containing curingingredients and measuring 152 3 228 3 0.5 mm (6 3 9 3 0.02in.) shall be placed on top of the specimen pad and filler layersover the cavity of the mold before the mo
28、ld cover is placed inposition.10.2.2.6 The purpose of the top rubber layer is to fill theoverflow space and seal the mold. In placing the specimen padin the mold, care shall be taken to keep uppermost that side ofthe specimen pad having the cords running crosswise.10.2.2.7 The total thickness of the
29、 material in the mold isthen 8.25 mm (0.325 in.) and expansion will produce anundistorted specimen pad.10.2.2.8 The mold shall be placed in a press under theconditions of pressure, temperature, and time to achievevulcanization of the material.10.2.2.9 After curing, the filler layers shall be removed
30、 andthe specimen pad allowed to equilibrate at an ambient tem-perature of between 21 and 32C (70 and 90F) for no less than36 h before being tested.10.2.2.10 Specimen pads made in this manner shall be 2033 127 3 7.07.1 mm (8 3 5 3 0.2750.280 in.).10.2.2.11 Any pads having distorted cords shall not be
31、tested.10.2.3 Cutting the Tire Test Specimens from the Pad:10.2.3.1 Four strips, each 203 3 25 mm (8 3 1 in.) shall becut from the tire specimen pad.10.2.3.2 First cut a strip 6.3 to 12.5 mm (0.250 to 0.50 in.)in width from one longitudinal edge of the specimen. Removeand discard this piece.4MethodA
32、was originated by General Laboratories, U.S. Rubber Co. For furtherinformation concerning this test see Gibbons, W. A.,“ Flexing Test for Tire CarcassStocks,” Industrial and Engineering Chemistry, Analytical Edition, Vol 2, No. 1,Jan. 15, 1930, p. 99; also Sturtevant, W. L., “Rubber Power Transmissi
33、on Belting,Part IIIFlexing Machine and Dynamometers for Testing Belting Quality,” IndiaRubber World, Vol 83, No. 3, 1930, p. 67.D430 06 (2012)210.2.3.3 Beginning from the first cut, remove four addi-tional strips, taking care to cut the strips straight with smoothedges. It is recommended to use a te
34、mplate as a cutting guide.10.2.3.4 In cutting the specimens, there should not be morethan five or six cut longitudinal threads exposed on the twoedges of a six ply specimen. A number of cut threads beyondfive or six is excessive and indicates that many of the threadsof alternate plies are not parall
35、el.11. Number of Test Specimens11.1 At least five specimens from each belt sample or tireand no less than four specimens from each tire specimen padshall be tested and the results averaged as indicated in Section16. Precision may be increased by testing a greater number ofspecimens.12. Scott Flexing
36、 Machine12.1 The essential features of the apparatus, illustrated inFig. 1, are as follows:12.1.1 The Scott flexing machine has five hubs and iscapable of testing up to five specimens at one time. Each hubrotates on a double row, radial type, ball bearing of the greasesealed type with double shields
37、.12.1.2 The test specimens shall be bent around the hubshaving an arc of contact of approximately 165, and the endsshall be gripped by clamps that are oscillated, up and down, byrocker arms driven through a chain of gears by a 190 W(0.25 hp) 1750 rpm motor.12.1.3 The action on the specimen is a flex
38、ing, back andforth, over the hub while held in tension by the loading leverand weight.12.1.4 The specimen has a travel in one direction of66.5 mm (2.62 in.) and a full cycle travel of 132.0 mm (5.2 in.).The speed of operation is approximately 2.7 Hz (160 cpm) withthe number of cycles in each test be
39、ing recorded by a counteraffixed to each rocker arm.13. Hub Size and Flexing Force13.1 Specimens from belts shall be tested using hubs31.7 mm (1.250 in.) in diameter with a 445 N (100 lbf) flexingforce.13.2 Specimens from tires or tire specimen pads shall betested using hubs 14.3 mm (0.563 in.) in d
40、iameter with a 445 N(100 lbf) flexing force.14. Procedure for Belt Specimens14.1 Bend the belt test specimens around the hubs with thepulley side of the belt against the metal and the ends clampedin the grips.14.2 Carefully apply the flexing load without shock, set thecounter to zero, and start the
41、machine. Allow it to run untilsome fine particles, dislodged by friction, may be seen on thewhite plate beneath the hub, which indicates that separation ofthe plies has started.14.3 Frequent inspection of the specimens undergoing testis imperative if reliable results are to be expected.14.4 When the
42、 first indication of ply separation appears,note and record the counter reading. Thereafter watch thespecimen more closely and increase the frequency of theinspection to ensure proper determination of the end point.14.5 When there is a clear separation across the width of thespecimen it shall be con
43、sidered to have failed. Record theminimum counter reading for this failure as the end point. Alsorecord the location of the separation.14.6 When a test is started, continue to completion withoutinterruption. However, for the purpose of examining thespecimen, each hub may be released momentarily from
44、 itsforce by means of the foot lever provided.15. Procedure for Tire Specimens15.1 Mount the tire test specimens with the lengthwise outerply cords against the hub of the machine and test in a mannersimilar to the procedure for belts (Section 14).15.2 After the tire specimen has been run about 10 mi
45、n, butbefore separation begins, brush a thick coat of molten carnaubawax on the outer side of the specimen at the flexing region.15.3 As soon as separation begins, the temperature of theflexing region increases very rapidly and the wax melts. Themelting of the wax starts with a small area and gradua
46、llyspreads as separation increases. This serves as a warning thatcomplete separation will occur shortly thereafter. The intervalbetween the melting of the wax (the time at which separationactually starts) and complete separation across the specimenmay not always be the same.NOTE 1A specimen with a s
47、hort flexing life will show completeseparation soon after the wax melts, whereas a sample with a greaterflexing life might require a time interval two or three times as long.However, with specimens having similar flexing life, the time intervalbetween the melting of the wax and complete separation i
48、s fairly constant.FIG. 1 Scott Flexing Machine with Five HubsD430 06 (2012)316. Calculation16.1 Calculate the result of the test of any sample as theaverage of the number of flexing cycles required to producecomplete separation of each test specimen as determined fromthe counter readings.METHOD B: D
49、EMATTIA FLEXING MACHINE517. Type of Strain17.1 The DeMattia flexing machine test method may beused to test rubber specimens for resistance to crackingproduced either by extension or bending, depending on therelative adjustment of the stationary and movable grips, and thedistance of travel of the latter. The choice of type of strain isoptional but notation shall be made of the type actually used,giving full details of the relative positions of the grips and ofthe travel.NOTE 2In choosing the type of strain, it should be remembered thatthe phenomenon of cracki
