1、Designation: D945 16Standard 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 revision, the year of l
2、ast 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 U.S. Department of Defense.1. Scope1.1 These test methods cover the use
3、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 set under a gi
4、ven 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 ha
5、vingresilience 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.
6、3 Computerized data acquisition systems and data evalu-ation methods for Yerzley Mechanical Oscillograph are in-cluded The mechanical portion of the oscillograph remains thesame. In the computerized type (digital data acquisition andrecording), the mechanical recording mechanism has beenreplaced wit
7、h a displacement transducer and digital dataacquisition system, by which the required calculations are suchthat the results are available immediately and recorded in realtime.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.
8、1.5 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-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specific
9、warning see 12.14.2. Referenced Documents2.1 ASTM Standards:4D832 Practice for Rubber Conditioning For Low Tempera-ture TestingD1207 Recommended Practice for Classifying ElastomericCompounds for Resilient Automotive Mountings (With-drawn 1971)5D4483 Practice for Evaluating Precision for Test MethodS
10、tandards 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 of Terms Specific to This Standard:3.2 effective dynamic moduluscalculated from the formulafor simple har
11、monic motion in a damped free oscillation. It isa composite index which includes the effect of such diversefactors as nonlinearity of stress-strain, changing molecularenergies, and heat losses.3.3 point modulusratio of total stress (force/area) to totalstrain (change in dimension/unstressed dimensio
12、n) at one point1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.10 on PhysicalTesting.Current edition approved July 1, 2016. Published July 2016. Originally approvedin 1948. Last previous edition approved in 2012 as D
13、945 06 (2012). DOI:10.1520/D0945-16.2A 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 1964, p. 36.3One method of correlating fundamental data from theYerzley osci
14、llograph 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, April 1950.4For referenced ASTM standards, visit the ASTM website, www.astm.org,
15、 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 approved version of this historical standard is referenced onwww.astm.org.6Available from Society of Automotive Engineer
16、s, 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 Technology,
17、Vol XIII, No. 1, January 1940, p. 149.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1of 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 m
18、odulussynonymous with “tangent modulus”and is the slope of the tangent to the stress-strain curve at achosen point. It can provide 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 def
19、lections 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 lever is supported on a knife edge, thesystem can be im
20、pact-loaded to produce a damped freeoscillation trace. This trace yields a dynamic modulus, aresilience index, an oscillation frequency, and a measurementof stored energy.4.2 Two test methods are described:4.2.1 Method A employs the the original Yerzley oscillo-graph with the mechanical data recordi
21、ng equipment consistingof a chronograph and a pen attached to the end of the beam.4.2.2 Method B introduces the displacement transducer anda data acquisition system, replacing the pen and chronograph.5. Significance and Use5.1 The rubber properties that are measurable by these testmethods are import
22、ant 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 to the unloaded surface ar
23、ea. 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(Method Aillustrated in illustrated in Fig. 1 and Fig. 2; Method Billustrated in Fig. 3) are as follows:6.1
24、.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 portions of thecross-rod, F, at the pen end of the beam. A second knife-edge,B, and a sta
25、bilizing 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 oscillograph.6.1.2 Method AA pen shall extend lengthwise from thebeam to record deflections o
26、n the oscillogram automatically.From Fig. 2, it is apparent that the deflection of the specimenunder test will be magnified by the travel of the pen inproportion to the lever ratio which will be 10:1 when thesample is on the inner test position, B.Therefore, a deformation8The sole source of supply o
27、f the Yerzley oscillograph known to the committeeat this time is Tavdi Co., Inc., P.O. Box 298, Barrington, RI 02806, www.tavdico-.com. If you are aware of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful consider-ation at a
28、 meeting of the responsible technical committee,1which you may attend.FIG. 1 Advanced Yerzley OscillographD945 162of 2.5 mm, for example, will be registered on the oscillogramas a vertical displacement of 25 mm.6.1.3 Method BThe pen and chronograph have beenreplaced with a displacement transducer an
29、d a data acquisitionsubsystem.6.1.4 The masses, MF,MG, and 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-
30、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 position. Using the 6.25:1 ratio, eachunbalanced mass on the pen end of the beam therefore willproduce the following forces
31、 on the specimen on the innerposition at W5r:FIG. 2 Diagrammatic Sketch of Advanced Yerzley OscillographFIG. 3 Method B Yerzley Oscillograph AYO-IV With Displacement Sensor and Computer SystemD945 163Mass ValueForce ResultingFrom 6.25:1 RatioSI units 489.46 g 30.000 NInch-pound units 1.4137 lb 8.835
32、7 lbf6.1.5 It follows that positioning the masses on the innermass position, MG, will reduce the load values to half of theforegoing values.PART IMEASUREMENTS IN COMPRESSION7. Test Specimens for Methods A then lock the micrometer by means of theset screw or lock nut. This setting can be verified as
33、follows:NOTE 1Silicon carbide particles have an average size of 22 6 2 m.9.2.1 Upon disengaging the release hook the recordingdevice (pen or transducer) end should retain its position. If therecording device (pen or transducer) drops noticeably, a changeof 0.02 mm (0.001 in.) may be visibly observed
34、, the microm-eter must 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 recording device (pen or transducer) end of thebeam. If the added force depresses the beam, the micrometerplaten is too low. Readjust t
35、he micrometer until the micrometersetting is correct. Opening and closing the release hook shouldthen have no effect on the position of the recording device (penor transducer).9.3 Method APlace the graph paper on the chronographdrum and adjust its position so that the zero position of the penpoint i
36、s on one of the horizontal lines of the paper. AnD945 164engineering grade of graph paper ruled in 1 in. squares andsubdivided into ten equal squares per inch shall be used formeasurements in inch-pound units. A quality grade of graphpaper ruled in 1 cm squares subdivided in millimeter squares ispre
37、ferable for measurements in SI units, although it should benoted that for 4 rpm and 1 rpm speeds of the chronograph 25.4mm on the horizontal 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 record
38、ing device end of the beam prior to recording boththe initial impact on the sample and the subsequent creep.Normally the test will be directed toward a final total defor-mation of 20 % plus the value of the creep. If creep of 2 %should develop, the total deformation thus would be 20+2%,or 22 %.Atole
39、rance of 62 % has been found convenient. Trialand error with one sample may be used to establish thenecessary number of masses. When the load value isestablished, proceed.9.5 With the hook engaged, a fresh test specimen, sandpaperin position, the correct micrometer setting, and the establishednumber
40、 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
41、.About three small squares into the second revolution releasethe hook, allowing the beam to fall in an impact on thespecimen, as indicated in Fig. 5. Allow the drum to rotate oneor more complete revolutions beyond the end of any oscilla-tions. Stop the motor. The creep of the sample after the end of
42、FIG. 4 Section of Oscillograph to be Enclosed for Tests at Other than Room TemperatureD945 165the oscillations will be recorded on the chart for 1 min or more.If desired, the creep for a longer time may be recorded bytiming a longer period and observing the further slow down-ward motion of the pen a
43、s a vertical downward trace. Theamount of further drift after the longer time interval can bemarked by a rotation of the drum one or two small squares tothe left and right by hand to form a cross on the trace line.9.6 Set may be measured at any time by reengaging thehook to remove the load from the
44、specimen, and then carefullyturning the micrometer platen downward a measured distanceinto contact with the sample to close the gap caused by theshort term set.9.7 Measurement of Initial Creep and Set with MethodBWith the beam elevated and with the hook engaged prepareto add masses to the transducer
45、 end of the beam prior torecording both the initial impact on the sample and thesubsequent creep. Normally the test will be directed toward afinal total deformation of 20 % plus the value of the creep. Ifcreep of 2 % should develop, the total deformation thus wouldbe20+2%,or22%.Atolerance of 62 % ha
46、s been foundconvenient. Trial and error with one sample may be used toestablish the necessary number of masses. When the load valueis established, proceed.9.8 With the hook engaged, a fresh test specimen, thecorrect micrometer setting, and the established number ofmasses installed, specify the “cree
47、p time” in seconds and selecta data file name; then push the START button and trigger thehook.9.9 Set may be measured at any time by reengaging thehook to remove the load from the specimen, and then carefullyturning the micrometer platen downward a measured distanceinto contact with the sample to cl
48、ose the gap caused by theshort term set.9.10 Measurement of Yerzley resilience and hysteresis, pointmodulus, frequency in hertz, effective dynamic modulus, andimpact energy absorbed by the sample at the test loadvalueTaken alone the procedure described in this section is arapid and informative test
49、for comparison of several propertiesof elastomers.9.11 This test is the natural sequel to the previous processfor creep, 9.4, or may be performed without a preceding creepand set evaluation after establishing the horizontal referenceline at the top of the chart as described in 9.3. With the hookengaged, verify the position of the test specimen with 400 gritA paper and the micrometer adjustment in firm but non-deforming contact with the specimen. With the estimatednumber of masses required to produce a final deformation of20 % and with the drum stationary, disengag
