1、Designation: D 7121 05Standard Test Method forRubber PropertyResilience Using Schob Type ReboundPendulum1This standard is issued under the fixed designation D 7121; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number 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 a means of determining theresilience of rubber, within a range of impact strain and strainrate, by
3、means of the impacting and measuring apparatusconforming to the requirements described in this test method.1.2 This test method is applicable to thermoset rubbers andthermoplastic elastomers, the hardness of which, at the speci-fied test temperatures, lies between 30 and 85 IRHD (see TestMethod D 14
4、15) or A/30 and A/85 (see Test Method D 2240).It may also be applicable to some polyester, polyether foam,and plastic foam materials.1.3 All materials, instruments, or equipment used for thedetermination of mass, force, or dimension shall have trace-ability to the National Institute for Standards an
5、d Technology,or other internationally recognized organization parallel innature.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with it
6、s 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:2D 832 Practice for Rubber Conditioning for Low-Temperature TestingD 134
7、9 Practice for RubberStandard Temperatures forTestingD 1415 Test Method for Rubber PropertyInternationalHardnessD 2240 Test Method for Rubber PropertyDurometerHardnessD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized Sheets
8、D 3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3. Summary of Test Method3.1 This test method describes the determination of resil-ience, expressed as
9、 percentage resilience or rebound resilience,by a Schob Type pendulum rebound device as a ratio betweenthe returned and applied energy when a spherically terminatedmass impacts a test specimen under the conditions specified inthis test method.3.2 Resilience of the materials described is infinitely v
10、ari-able. It varies with temperature, strain rate (specifically relatedto the velocity of the indentor), and strain energy (specificallyrelated to the mass of the indentor, coupled with velocity).3.3 The variable factors, described and defined in this testmethod, will have effects on the outcomes of
11、 test results.Repetitive tests, under the defined conditions, on comparablematerials, will provide meaningful, repeatable, and reproduc-ible data.4. Significance and Use4.1 The Schob Type rebound pendulum is designed tomeasure the percentage resilience of a rubber compound as anindication of hystere
12、tic energy loss that can also be defined bythe relationship between storage modulus and loss modulus.The percent rebound measured is inversely proportional to thehysteretic loss.4.1.1 Percentage resilience or rebound resilience are com-monly used in quality control testing of polymers and com-poundi
13、ng chemicals.4.1.2 Rebound resilience is determined by a freely fallingpendulum hammer that is dropped from a given height thatimpacts a test specimen and imparts to it a certain amount ofenergy. A portion of that energy is returned by the specimen to1This test method is under the jurisdiction of AS
14、TM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.14 on Time and Temperature-Dependent Physical Properties.Current edition approved June 1, 2005. Published June 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、serviceastm.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.the pendulum and may be measured by the extent to w
16、hich thependulum rebounds, whereby the restoring force is determinedby gravity.4.1.2.1 Since the energy of the pendulum is proportional tothe vertical component of the displacement of the pendulum, itmay be expressed as 1 cos (of the angle of displacement) andpercentage rebound resilience. RB, commo
17、nly called percent-age rebound, is determined from the equation:RB 51 2 cos angle of rebound!1 2 cos original angle!3 100 (1)4.1.2.2 The rebound resilience may be calculated as:R 5hH(2)where:h = apex height of the rebound, andH = initial height.4.1.2.3 The rebound resilience may also be determined b
18、ythe measurement of the angle of rebound a. From the reboundangle a, the rebound resilience in percent is obtained accordingto the following formula:R 5 1 2 cos a! 3 100 (3)5. Apparatus5.1 Rebound resilience shall be measured by means of aSchob Type pendulum rebound device (see Fig. 1), which maybe
19、described as a pendulum-like, one-degree-of-freedom, me-chanical oscillatory rebound device.5.1.1 The device shall consist of a pendulum rod terminat-ing in a hammer and hammer peen (spherical indentor)supported by a frame (see Fig. 2) so as to oscillate linearly orcircularly under the action of a r
20、estoring force, which may bedue to gravity or the elastic reactions of a torsion wire orsprings. It shall also incorporate a specimen holder and adevice by which to determine the outcome of the resiliencetest, either an analog scale with a pointer, or an equivalentdigital electronic display.5.2 The
21、scale or display shall read either, or both, the angleof rebound and the horizontal rebound distance. The scale ordisplay may be graduated uniformly or be calibrated in units ofresilience.5.3 The test specimen shall be securely held during me-chanical conditioning and rebound measurement.5.3.1 The s
22、urface against which the back of the test speci-men is applied shall be metallic, flat, and smoothly finished,vertical and perpendicular to the impact velocity direction.5.3.2 This flat face is a part of an anvil which shall, if free,have a mass of least 200 times the impacting mass.5.3.3 Any type o
23、f suitable holding device may be usedprovided that it gives rebound resilience values that deviate notmore than 0.2 (absolute rebound resilience) from those ob-tained with test specimens bonded to a rigid back plate.5.3.3.1 Examples of suitable holding devices include suc-tion (by vacuum), mechanica
24、l clamping devices, and combi-nations of the two.5.3.3.2 No lateral restraint shall be applied to the testspecimen in order to allow it to bulge freely when impacted.5.4 If measurements are to be carried out at a series oftemperatures different from the ambient temperature, the pen-dulum instrument
25、shall be operated in accordance with Prac-tices D 832 and D 1349.5.4.1 The apparatus shall be checked for correct operation inthe range of temperatures used.5.4.2 Samples shall be conditioned at temperature andremoved as quickly as possible to the tester (see 8.1.3).6. Test Specimens6.1 Test specime
26、ns shall be prepared in accordance withPractices D 3182 and D 3183 either by molding or by cutting.They shall be free of fabric or any other reinforcing materials.6.2 Test specimen size shall be as described by the instru-ment manufacturer or as agreed upon by supplier and customer.6.3 The test spec
27、imens shall have flat, smooth, and parallelsurfaces, finished, if necessary, by buffing. If the impactedsurface is cohesive, the effect shall be minimized by dustingthe surface with talc or an equivalent material.6.3.1 Specimens may be prepared by plying samples cutfrom a standard test slab (see Pra
28、ctices D 3182 and D 3183).These samples shall be plied, without cementing, to thethickness required. Such plies shall be smooth, flat, and ofuniform thickness. The results obtained with these specimensso prepared will not necessarily be identical with thoseobtained using a solid specimen of the same
29、 material and stateof cure.6.3.1.1 Plying of no more than three test specimens of thesame material may be used to obtain a greater thickness. It isnecessary that the surfaces of the test specimens be verysmooth, and lateral suction may help in ensuring their contact.6.3.1.2 Plying of test specimens
30、introduces additional un-certainties, and shall be used only for comparative measure-ments.6.4 The test shall be performed no earlier than 16 h and nolater than 28 days beyond the time of vulcanization.6.5 The time between vulcanization and testing shall notexceed 120 days for finished articles.6.5.
31、1 Alternatively, the time between vulcanization andtesting may be agreed upon between laboratories or customerand supplier.6.6 Samples and test specimens shall be protected from lightas completely as possible during the interval between vulcani-zation and testing.6.7 If the test specimen is buffed,
32、the interval betweenbuffing and testing shall not exceed 72 h.7. Tester Verification7.1 Since there are no absolute standards available for thistester, the instruments performance should be verified on aregular basis:7.1.1 Follow manufacturers recommendations for physicalverification of the instrume
33、nt.7.1.2 Obtain or produce one or two standard samples,preferably one with high (90 %) resilience and one with lowD7121052(20 to 30 %) resilience. Test these samples normally to verifyinstrument performance.8. Test Conditions8.1 The standard laboratory temperature of 23 6 2C (73.46 3.6F) is the pref
34、erred temperature of the test.8.1.1 Tests may also be carried out at other temperatures asagreed upon between laboratories or customer and supplier.8.1.2 The temperature tolerance shall not exceed 61C.8.1.3 When tests are conducted at temperatures other thanthat in 8.1, the sample should be conditio
35、ned for at least 30 minor until uniformity of temperature is reached, then removedquickly to the tester to reduce the temperature change beforetesting.9. Procedure9.1 After conditioning and mounting the test specimen inthe holding device, carry out mechanical conditioning bysubjecting the test speci
36、men to no fewer than three and notmore than seven successive impacts, so as to reach a practicallyconstant rebound amplitude.9.2 Immediately after the impacts for mechanical condition-ing, apply three more impacts at the same velocity to testspecimen and note the three rebound readings.9.3 Convert t
37、hese three readings, if necessary (see Section4), to resilience values, expressed as a percentage. Theirmedian shall be taken as the rebound resilience of the testspecimen.1 Bubble Level2 Release3 Pendulum Angle Adjusting Screw4 Pendulum Mass5 Hammer (indentor)6 Anvil7 Leveling Feet8 Anvil Positioni
38、ng Screw9 Power Switch10 Display11 Observation Window12 Specimen HolderFIG. 1 Typical Schob Type Pendulum Rebound ApparatusD71210539.4 Calculate the average of the values for the two (or more)test specimens.10. Test Report10.1 The test report shall include:10.2 Test Details:10.2.1 Full description o
39、f the sample and its origin, includ-ing vulcanization date,10.2.2 Dimensions of the test specimen,10.2.3 Compound details and curing conditions, if known,10.2.4 Preparation of test specimens, for example whethermolded or cut and if the specimens were plied,10.2.5 Any relevant facts about the pretest
40、 history of testspecimens,10.2.6 Apparatus employed, and10.2.7 Methodology used.10.3 Test Results:10.3.1 Number of test specimens tested, and10.3.2 Calculated mean value or rebound resilience, inpercent, for the test specimens.11. Precision and Bias11.1 Precision and bias have not been determined. A
41、ninterlaboratory test program (ITP) will be conducted within theallotted time.11.2 The standard definitions relative to precision and bias,as defined in Practice D 4483, have been included for refer-ence.12. Keywords12.1 impact; oscillatory device; pendulum rebound; re-bound; resilience; rubberASTM
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44、 should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on
45、 Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 2 Schematic Detail of the Schob DeviceD7121054
