ASTM D945-2006 Standard Test Methods for Rubber Properties in Compression or Shear (Mechanical Oscillograph)《在压缩应力和剪切应力下橡胶特性的试验方法（机械示波器）》.pdf

《ASTM D945-2006 Standard Test Methods for Rubber Properties in Compression or Shear (Mechanical Oscillograph)《在压缩应力和剪切应力下橡胶特性的试验方法（机械示波器）》.pdf》由会员分享，可在线阅读，更多相关《ASTM D945-2006 Standard Test Methods for Rubber Properties in Compression or Shear (Mechanical Oscillograph)《在压缩应力和剪切应力下橡胶特性的试验方法（机械示波器）》.pdf（11页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 945 06Standard Test Methods forRubber Properties in Compression or Shear (MechanicalOscillograph)1This standard is issued under the fixed designation D 945; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of

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

3、 the Yerzley me-chanical oscillograph for measuring mechanical properties ofrubber vulcanizates in the generally small range of deformationthat characterizes many technical applications. These proper-ties include resilience, dynamic modulus, static modulus,kinetic energy, creep, and set under a give

4、n force. Measure-ments in compression and shear are described.2,31.2 The test is applicable primarily, but not exclusively, tomaterials having static moduli at the test temperature such thatforces below 2 MPa (280 psi) in compression or 1 MPa(140 psi) in shear will produce 20 % deformation, and havi

5、ngresilience such that at least three complete cycles are producedwhen obtaining the damped oscillatory curve. The range maybe extended, however, by use of supplementary masses andrefined methods of analysis. Materials may be compared eitherunder comparable mean stress or mean strain conditions.1.3

6、The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 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-p

7、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specificwarning see 12.14.2. Referenced Documents2.1 ASTM Standards:4D 832 Practice for Rubber Conditioning For Low Tempera-ture TestingD 1207 Recommended Practice for Classifying Elastom

8、ericCompounds for Resilient Automotive Mountings5D 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2 SAE Standard:SAE J16 Classification of Elastomer Compounds for Auto-motive Resilient Mountings6,73. Terminology3.1 Descriptions

9、 of Terms Specific to This Standard:3.2 effective dynamic moduluscalculated from the for-mula for simple harmonic motion in a damped free oscillation.It is a composite index which includes the effect of suchdiverse factors as nonlinearity of stress-strain, changing mo-lecular energies, and heat loss

10、es.3.3 point modulusratio of total stress (force/area) to totalstrain (change in dimension/unstressed dimension) at one pointof the stress-strain curve. Sometimes called the “secant modu-lus,” it is equal to the slope of a line from the origin to thechosen point.3.4 static modulussynonymous with “ta

11、ngent modulus”and is the slope of the tangent to the stress-strain curve at a1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.14 on Time andTemperature-Dependent Physical Properties.Current edition approved July 1, 20

12、06. Published July 2006. Originally approvedin 1948. Last previous edition approved in 2001 as D 945 92 (2001)e1.2A survey of some aspects of hysteresis and modulus in dynamic performanceof polymers is available in a paper by Payne, A. R., “The Role of Hysteresis inPolymers,” Rubber Journal, January

13、 1964, p. 36.3One method of correlating fundamental data from theYerzley oscillograph withdynamic tests at constant amplitude is described by Baldwin, F. P., in his paper,“Determination of the Dynamic Properties of Rubberlike Materials by Means of aModified Yerzley Oscillograph,” The Rubber Age, Apr

14、il 1950.4For 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 standards Document Summary page onthe ASTM website.5Withdrawn.6Available from Society of Automotive Engi

15、neers, 400 Commonwealth Drive,Warrendale, PA 15096.7The Yerzley oscillograph was originally described in detail in the paper byYerzley, F. L., “A Mechanical Oscillograph for Routine Tests of Rubber andRubber-Like Materials,” Proceedings, ASTM, Vol 39, 1939, p. 1180; also RubberChemistry and Technolo

16、gy, Vol XIII, No. 1, January 1940, p. 149.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.chosen point. It can provide a reference for comparison withthe effective dynamic modulus at that point.4. Summary of Test Methods4.1 Specimens

17、 are loaded by an unbalanced lever and theresultant deflections are recorded on a chronograph. Thispermits calculations to be made of static modulus at any stageof a stepwise loading or unloading schedule. Creep andrecovery rates, including set under prescribed conditions, canbe obtained. Since the

18、lever is supported on a knife edge, thesystem can be impact-loaded to produce a damped freeoscillation trace. This trace yields a dynamic modulus, aresilience index, an oscillation frequency, and a measurementof stored energy.5. Significance and Use5.1 The rubber properties that are measurable by th

19、ese testmethods are important for the isolation and absorption of shockand vibration.These properties may be used for quality control,development and research.5.2 Measurements in compression are influenced by speci-men shape. This shape factor may be described as the ratio ofthe loaded surface area

20、to the unloaded surface area. Inapplying data from a compression specimen, shape factor mustbe incorporated into the mathematical transferal to the appli-cation.6. Apparatus6.1 The essential features of the apparatus7,8(illustrated inFig. 1 and Fig. 2) are as follows:6.1.1 The beam shall be supporte

21、d at its center by aknife-edge, A, and shall be so designed that a test specimenplaced beneath the micrometer can be loaded by placingstandard masses alternatively on front and back portions of thecross-rod, F, at the pen end of the beam. A second knife-edge,B, and a stabilizing arm, B8, (as shown i

22、n Fig. 2), shall be usedto apply load to the test specimen and to maintain parallelismof the loading platens. Optional knife-edges, C and D, may beused to extend the range of the oscillograph.6.1.2 Apen shall extend lengthwise from the beam to recorddeflections on the oscillogram automatically. From

23、 Fig. 2,itisapparent that the deflection of the specimen under test will bemagnified by the travel of the pen in proportion to the leverratio which will be 10:1 when the sample is on the inner testposition, B. Therefore, a deformation of 2.5 mm, for example,will be registered on the oscillogram as a

24、 vertical displacementof 25 mm.6.1.3 The masses, MF,MG, and MH, derive from the mass ofaccurately machined disks, 99.06 mm in diameter with a8The sole source of supply of the Yerzley oscillograph known to the committeeat this time is Tavdi Co., Inc., P.O. Box 298, Barrington, RI 02806. If you are aw

25、areof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.FIG. 1 Advanced Yerzley OscillographD945062central hole 12.7 mm in diameter. Stand

26、ard masses shall be anintegral or fractional multiple either of 641.252 g (1.41372 lb)for convenience of testing in inch-pound units or of 489.464 gfor greater convenience of testing in SI units. The lever ratiofor the masses is 6.25:1 for the outer mass position in referenceto the inner specimen po

27、sition. Using the 6.25:1 ratio, eachunbalanced mass on the pen end of the beam therefore willproduce the following forces on the specimen on the innerposition at W5r:Mass ValueForce ResultingFrom 6.25:1 RatioSI units 489.46 g 30.000 NInch-pound units 1.4137 lb 8.8357 lbf6.1.4 It follows that positio

28、ning the masses on the innermass position, MG, will reduce the load values to half of theforegoing values.PART AMEASUREMENTS IN COMPRESSION7. Test Specimens7.1 Solid Rubber Specimens:7.1.1 At least two specimens shall be tested, except that atleast three shall be required if measurement of creep is

29、to beincluded. The test specimens for measurements in compressionshall be right circular cylinders chosen from the followingalternatives:Shape PrimaryFactor Practice Diameter0.390 SI units 19.5 6 0.13 mm0.375 Inch-pound units 0.75 6 0.005 in.Reference AreaShape of NominalFactor Height Circle0.390 12

30、.5 6 0.25 mm 300 mm20.375 0.5 6 0.010 in. 0.442 in.27.1.2 The specimens may be molded, or cut from finishedproducts and buffed to the specified dimensions. Test speci-mens shall be free from porosity, nicks, and cuts. (Moldedspecimens are preferred for dimensional accuracy and consis-tency.)7.2 Cell

31、ular Test Specimens:7.2.1 Specimens of cellular rubber shall be prepared asfollows: The specimen shall be a circular cylinder cut with acircular metal die 43.70 6 0.01 mm (1.720 6 0.001 in.) ininside diameter for cutting the specimen in a drill press orsimilar device for rotating the die. The pressu

32、re applied to thedie shall be sufficiently small to keep “cupping” of the cutsurfaces to a minimum. In some cases, it may be necessary tofreeze the cellular rubber before cutting the specimen in orderto obtain parallel cut surfaces. To facilitate cutting of thespecimen with smooth-cut surfaces and s

33、quare edges, the diemay be lubricated with water containing a wetting agent and acorrosion inhibitor such as 0.5 % sodium chromate or withsilicone mold release emulsion before each specimen is cut. Ifa lubricant is used, the specimen shall be permitted to drybefore testing. The circular bases of the

34、 specimens shall beparallel to each other and at right angles to the axis of thecylinder. The area of the circular bases is 15.00 cm2(2.323 in.2).FIG. 2 Diagrammatic Sketch of Advanced Yerzley OscillographD9450637.2.2 The specimen shall be not less than 6.4 mm (0.25 in.)and not more than 29 mm (1.12

35、5 in.) in thickness. If thematerial is too thick, it shall be sliced to the required thickness.7.2.3 Unless otherwise specified in the detail specification,materials thinner than 6.4 mm (0.25 in.) shall be plied up toobtain the required thickness, in which case the report is toinclude the number of

36、plies.8. Conditioning8.1 Expose the test specimens and the apparatus to thetemperature of the test for sufficient time to ensure temperatureequilibrium. For testing at low temperatures (below roomtemperature), the section of the oscillograph to be enclosedshall be one of those shown by broken lines

37、in Fig. 3. Theenclosure shall be equipped with a shelf for storing testspecimens and supplied with a circulating atmosphere at thetemperature of test. Unless otherwise specified, the coldchamber and testing conditions shall conform to the conditionsspecified in Practice D 832.After the test specimen

38、s have beenconditioned at the test temperature, proceed in accordance withSection 9. Similar conditioning requirements apply also to testsat elevated temperatures.9. Procedure9.1 Procedure for Solid Rubber SpecimensThree catago-ries of test operation are described separately under subsequentsection

39、headings to provide data for purposes as follows:9.1.1 In 9.4-9.6 for initial creep and set under a given load.9.1.2 In 9.7-9.9 for Yerzley resilience and hysteresis, pointmodulus, frequency in hertz, effective dynamic modulus, andmaximum impact energy absorbed at a given test load value.9.1.3 In 9.

40、10-9.14 for stepwise loading and unloading andhysteresis loop, and stresses in pascals or in pounds-force persquare inch at any deformation.9.1.4 Depending on the purpose of any test program, pri-mary reliance may be placed on any one of the foregoingcategories, on a combination of two categories, o

41、r upon allFIG. 3 Section of Oscillograph to be Enclosed for Tests at Other than Room TemperatureD945064three. It is important, however, to record adequately all datarequired to identify the test conditions fully.9.2 Lock the beam of the oscillograph in position by meansof the release hook at the lef

42、t end of the machine and removeall masses. Place the test specimen centrally on the lowerplaten between the grit sides of two pieces of 400 grit Asandpaper (Note 1). Adjust the micrometer until the upperplaten rests snugly against the sandpaper without deformingthe test specimens; then lock the micr

43、ometer by means of theset screw or lock nut. This setting can be verified as follows:NOTE 1Silicon carbide particles have an average size of 22 6 2 m.9.2.1 Upon disengaging the release hook the pen end shouldretain its position. If the pen drops noticeably, a change of0.02 mm (0.001 in.) may be visi

44、bly observed, the micrometermust be readjusted downward.9.2.2 When this adjustment is completed and verified,reengage the hook. Now apply a small downward force byhand on the pen end of the beam. If the added force depressesthe pen, the micrometer platen is too low. Readjust themicrometer until the

45、micrometer setting is correct. Openingand closing the release hook should then have no effect on thepen position.9.3 Place the graph paper on the chronograph drum andadjust its position so that the zero position of the pen point ison one of the horizontal lines of the paper. An engineeringgrade of g

46、raph paper ruled in 1 in. squares and subdivided intoten equal squares per inch shall be used for measurements ininch-pound units. A quality grade of graph paper ruled in 1 cmsquares subdivided in millimeter squares is preferable formeasurements in SI units, although it should be noted that for4 rpm

47、 and 1 rpm speeds of the chronograph 25.4 mm on thehorizontal scale equals 1 and 4 s, respectively.9.4 Measurement of Initial Creep and SetWith the beamelevated and with the hook engaged prepare to add masses tothe pen end of the beam prior to recording both the initialimpact on the sample and the s

48、ubsequent creep. Normally thetest will be directed toward a final total deformation of 20 %plus the value of the creep. If creep of 2 % should develop, thetotal deformation thus would be 20+2%,or22%.Atoleranceof 62 % has been found convenient. Trial and error with onesample may be used to establish

49、the necessary number ofmasses. When the load value is established, proceed.9.5 With the hook engaged, a fresh test specimen, sandpaperin position, the correct micrometer setting, and the establishednumber of masses installed, switch on the power to the drum,to rotate at 4 rpm in order to draw the horizontal reference lineat the top of the chart. This will also take up slack in the geartrain driving the drum. As the drum approaches the beginningof the second revolution, change the drum speed to 1 rpm.About three small squares into the second revolution releasethe hook, allowi