1、Designation: D945 06 (Reapproved 2012)Standard Test Methods forRubber Properties in Compression or Shear (MechanicalOscillograph)1This standard is issued under the fixed designation D945; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods c
3、over the use of 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 s
4、et under a given 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 % deform
5、ation, and havingresilience 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
6、conditions.1.3 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 es
7、tablish appro-priate 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:4D832 Practice for Rubber Conditioning For Low Tempera-ture TestingD1207 Recommended Practice for Classi
8、fying ElastomericCompounds for Resilient Automotive Mountings (With-drawn 1971)5D4483 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 Mountings6,7
9、3. Terminology3.1 Descriptions of Terms Specific to This Standard:3.2 effective dynamic moduluscalculated from the formulafor simple harmonic motion in a damped free oscillation. It isa composite index which includes the effect of such diversefactors as nonlinearity of stress-strain, changing molecu
10、larenergies, and heat losses.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 “secantmodulus,” it is equal to the slope of a line from the origin to thechosen point.3.4 static mo
11、dulussynonymous with “tangent 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 edi
12、tion approved Dec. 1, 2012. Published February 2013. Originallyapproved in 1948. Last previous edition approved in 2006 as D945 06. DOI:10.1520/D0945-06R12.2A survey of some aspects of hysteresis and modulus in dynamic performanceof polymers is available in a paper by Payne, A. R., “The Role of Hyst
13、eresis inPolymers,” Rubber Journal, January 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
14、 Yerzley Oscillograph,” The Rubber Age, April 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.5The last
15、approved version of this historical standard is referenced onwww.astm.org.6Available from Society of Automotive Engineers, 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 Te
16、sts of Rubber andRubber-Like Materials,” Proceedings, ASTM, Vol 39, 1939, p. 1180; also RubberChemistry and Technology, Vol XIII, No. 1, January 1940, p. 149.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1chosen point. It can provide
17、 a reference for comparison withthe effective dynamic modulus at that point.4. Summary of Test Methods4.1 Specimens 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
18、 unloading schedule. Creep andrecovery rates, including set under prescribed conditions, canbe obtained. Since the 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 freq
19、uency, and a measurementof stored energy.5. Significance and Use5.1 The rubber properties that are measurable by these 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 compre
20、ssion are influenced by speci-men shape. This shape factor may be described as the ratio ofthe loaded surface area 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 esse
21、ntial features of the apparatus7,8(illustrated inFig. 1 and Fig. 2) are as follows:6.1.1 The beam shall be supported 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 por
22、tions of thecross-rod, F, at the pen end of the beam. A second knife-edge,B, and a stabilizing arm, B, (as shown in 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 oscillo
23、graph.6.1.2 Apen shall extend lengthwise from the beam to recorddeflections on the oscillogram automatically. From 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
24、 inner testposition, B. Therefore, a deformation of 2.5 mm, for example,will be registered on the oscillogram as a vertical displacementof 25 mm.8The 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 ar
25、e awareof 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 OscillographD945 06 (2012)26.1.3 The masses, MF,MG, an
26、d MH, derive from the mass ofaccurately machined disks, 99.06 mm in diameter with acentral hole 12.7 mm in diameter. Standard 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 tes
27、ting in SI units. The lever ratiofor the masses is 6.25:1 for the outer mass position in referenceto the inner specimen position. 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 ValueFo
28、rce 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 positioning 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 Speci
29、mens:7.1.1 At least two specimens shall be tested, except that atleast three shall be required if measurement of creep is to beincluded. The test specimens for measurements in compressionshall be right circular cylinders chosen from the followingalternatives:Shape PrimaryFactor Practice Diameter0.39
30、0 SI units 19.5 0.13 mm0.375 Inch-pound units 0.75 0.005 in.Reference AreaShape of NominalFactor Height Circle0.390 12.5 0.25 mm 300 mm20.375 0.5 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
31、from porosity, nicks, and cuts. (Moldedspecimens are preferred for dimensional accuracy and consis-tency.)7.2 Cellular 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
32、in.) ininside diameter for cutting the specimen in a drill press orsimilar device for rotating the die. The pressure 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 spe
33、cimen in orderto obtain parallel cut surfaces. To facilitate cutting of thespecimen with smooth-cut surfaces and square 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 speci
34、men is cut. IfFIG. 2 Diagrammatic Sketch of Advanced Yerzley OscillographD945 06 (2012)3a lubricant is used, the specimen shall be permitted to drybefore testing. The circular bases of the specimens shall beparallel to each other and at right angles to the axis of thecylinder. The area of the circul
35、ar bases is 15.00 cm2(2.323 in.2).7.2.2 The specimen shall be not less than 6.4 mm (0.25 in.)and not more than 29 mm (1.125 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
36、 6.4 mm (0.25 in.) shall be plied up toobtain the required thickness, in which case the report is toinclude the number of 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 temper
37、atures (below roomtemperature), the section of the oscillograph to be enclosedshall be one of those shown by broken lines 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,
38、 the coldchamber and testing conditions shall conform to the conditionsspecified in Practice D832. After the test specimens have beenconditioned at the test temperature, proceed in accordance withSection 9. Similar conditioning requirements apply also to testsat elevated temperatures.9. Procedure9.1
39、 Procedure for Solid Rubber SpecimensThree catago-ries of test operation are described separately under subsequentsection 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, pointmodulu
40、s, frequency in hertz, effective dynamic modulus, andmaximum impact energy absorbed at a given test load value.FIG. 3 Section of Oscillograph to be Enclosed for Tests at Other than Room TemperatureD945 06 (2012)49.1.3 In 9.10-9.14 for stepwise loading and unloading andhysteresis loop, and stresses i
41、n 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, or upon allthree. It is important, however, to record adequately all datarequi
42、red to identify the test conditions fully.9.2 Lock the beam of the oscillograph in position by meansof the release hook at the left 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). Adju
43、st the micrometer until the upperplaten rests snugly against the sandpaper without deformingthe test specimens; then lock the micrometer 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 disengagi
44、ng the release hook the pen end shouldretain its position. If the pen drops noticeably, a change of0.02 mm (0.001 in.) may be visibly 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
45、 the pen end of the beam. If the added force depressesthe pen, the micrometer platen is too low. Readjust themicrometer until the 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 andadju
46、st its position so that the zero position of the pen point ison one of the horizontal lines of the paper. An engineeringgrade of graph 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
47、 1 cmsquares subdivided in millimeter squares is preferable formeasurements in SI units, although it should be noted that for4 rpm 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
48、the hook engaged prepare to add masses tothe pen end of the beam prior to recording both the initialimpact on the sample and the subsequent 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 deformati
49、on thus would be 20+2%,or22%.Atoleranceof 62 % has been found convenient. Trial and error with onesample may be used to establish 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
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