ASTM D7121-2005(2018) 0000 Standard Test Method for Rubber Property&x2014 Resilience Using Schob Type Rebound Pendulum.pdf

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1、Designation: D7121 05 (Reapproved 2018)Standard Test Method forRubber PropertyResilience Using Schob Type ReboundPendulum1This standard is issued under the fixed designation D7121; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th

2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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

3、strainrate, by 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

4、TestMethod D1415) or A/30 and A/85 (see Test Method D2240). Itmay also be applicable to some polyester, polyether foam, andplastic 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

5、 Standards and 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, assoc

6、iated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally rec

7、ognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D832 Practice for R

8、ubber Conditioning For Low Tempera-ture TestingD1349 Practice for RubberStandard Conditions for Test-ingD1415 Test Method for Rubber PropertyInternationalHardnessD2240 Test Method for Rubber PropertyDurometer Hard-nessD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard

9、 Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3. Summary of Test Method3.1 This test method describe

10、s the determination ofresilience, expressed as percentage resilience or reboundresilience, by a Schob Type pendulum rebound device as a ratiobetween the returned and applied energy when a sphericallyterminated mass impacts a test specimen under the conditionsspecified in this test method.3.2 Resilie

11、nce of the materials described is infinitely vari-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 te

12、stmethod, will have effects on the outcomes of test results.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand Rubber-like Materials and is the direct responsibility of Subcommittee D11.10on Physical Testing.Current edition approved June 1, 2018. Published August 2018. Or

13、iginallyapproved in 2005. Last previous edition approved in 2012 as D7121 05 (2012).DOI: 10.1520/D7121-05R18.2For 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 sta

14、ndards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the De

15、cision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1Repetitive tests, under the defined conditions, on comparablematerials, will provide meaningful, repeatable, and reproduc

16、-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 hysteretic energy loss that can also be defined bythe relationship between storage modulus and loss modulus.The percent rebound measured is in

17、versely proportional to thehysteretic loss.4.1.1 Percentage resilience or rebound resilience are com-monly used in quality control testing of polymers and com-pounding chemicals.4.1.2 Rebound resilience is determined by a freely fallingpendulum hammer that is dropped from a given height thatimpacts

18、a test specimen and imparts to it a certain amount ofenergy. A portion of that energy is returned by the specimen tothe pendulum and may be measured by the extent to which thependulum rebounds, whereby the restoring force is determinedby gravity.4.1.2.1 Since the energy of the pendulum is proportion

19、al tothe vertical component of the displacement of the pendulum, itmay be expressed as 1 cos (of the angle of displacement) andpercentage rebound resilience. RB, commonly called percent-age rebound, is determined from the equation:RB 51 2 cos angle of rebound!1 2 cos original angle!3100 (1)4.1.2.2 T

20、he 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 bythe measurement of the angle of rebound . From the reboundangle , the rebound resilience in percent is obtained accordingto the follo

21、wing formula:R 5 1 2 cos ! 3100 (3)5. Apparatus5.1 Rebound resilience shall be measured by means of aSchob Type pendulum rebound device (see Fig. 1), which maybe described as a pendulum-like, one-degree-of-freedom, me-chanical oscillatory rebound device.5.1.1 The device shall consist of a pendulum r

22、od 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 restoring force, which may bedue to gravity or the elastic reactions of a torsion wire orsprings. It shall also incorporate a specimen hold

23、er 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 scale or display shall read either, or both, the angleof rebound and the horizontal rebound distance. The scale ordisplay may be graduated

24、 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 surface against which the back of the test speci-men is applied shall be metallic, flat, and smoothly finished,vertical and perpendicular t

25、o 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 of suitable holding device may be usedprovided that it gives rebound resilience values that deviate notmore than 0.2 (absolute rebound resi

26、lience) 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), mechanical 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

27、 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 shall be operated in accordance with Prac-tices D832 and D1349.5.4.1 The apparatus shall be checked for correct operation inthe range of t

28、emperatures 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 specimens shall be prepared in accordance withPractices D3182 and D3183 either by molding or by cutting.They shall be free of fabric or any other r

29、einforcing 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 specimens shall have flat, smooth, and parallelsurfaces, finished, if necessary, by buffing. If the impactedsurface is cohesive, the effect shall

30、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 Practices D3182 and D3183).These samples shall be plied, without cementing, to thethickness required. Such plies shall be smooth, flat, and ofuni

31、form thickness. The results obtained with these specimensso prepared will not necessarily be identical with thoseobtained using a solid specimen of the same 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

32、 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 introduces additionaluncertainties, and shall be used only for comparative measure-ments.6.4 The test shall be performed no earlier than 16 h an

33、d nolater than 28 days beyond the time of vulcanization.D7121 05 (2018)26.5 The time between vulcanization and testing shall notexceed 120 days for finished articles.6.5.1 Alternatively, the time between vulcanization andtesting may be agreed upon between laboratories or customerand supplier.6.6 Sam

34、ples 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, the interval betweenbuffing and testing shall not exceed 72 h.1 Bubble Level2 Release3 Pendulum Angle Adjusting Screw4 Pendulum Ma

35、ss5 Hammer (indentor)6 Anvil7 Leveling Feet8 Anvil Positioning Screw9 Power Switch10 Display11 Observation Window12 Specimen HolderFIG. 1 Typical Schob Type Pendulum Rebound ApparatusFIG. 2 Schematic Detail of the Schob DeviceD7121 05 (2018)37. Tester Verification7.1 Since there are no absolute stan

36、dards available for thistester, the instruments performance should be verified on aregular basis:7.1.1 Follow manufacturers recommendations for physicalverification of the instrument.7.1.2 Obtain or produce one or two standard samples,preferably one with high (90 %) resilience and one with low(20 to

37、 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 preferred temperature of the test.8.1.1 Tests may also be carried out at other temperatures asagreed upon between laboratories or cu

38、stomer 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 conditioned for at least 30 minor until uniformity of temperature is reached, then removedquickly to the tester to reduce the temperatur

39、e change beforetesting.9. Procedure9.1 After conditioning and mounting the test specimen inthe holding device, carry out mechanical conditioning bysubjecting the test specimen to no fewer than three and notmore than seven successive impacts, so as to reach a practicallyconstant rebound amplitude.9.2

40、 Immediately after the impacts for mechanicalconditioning, apply three more impacts at the same velocity totest specimen and note the three rebound readings.9.3 Convert these three readings, if necessary (see Section4), to resilience values, expressed as a percentage. Theirmedian shall be taken as t

41、he rebound resilience of the testspecimen.9.4 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 of the sample and its origin, includ-ing vulcanization date,10.2.2 Dimensions of the test

42、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 history of testspecimens,10.2.6 Apparatus employed, and10.2.7 Methodology used.10.3 Test

43、 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. Aninterlaboratory test program (ITP) will be conducted within theallotted time.11.2 The st

44、andard definitions relative to precision and bias,as defined in Practice D4483, have been included for reference.12. Keywords12.1 impact; oscillatory device; pendulum rebound; re-bound; resilience; rubberASTM International takes no position respecting the validity of any patent rights asserted in co

45、nnection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the respo

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