1、Designation: D 623 07Standard Test Methods forRubber PropertyHeat Generation and Flexing Fatigue InCompression1This standard is issued under the fixed designation D 623; 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods may be used to compare the fatiguecharacteristics and rate of heat generation of different rubbervu
3、lcanizates when they are subjected to dynamic compressivestrains.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
4、s 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 395 Test Methods for Rubber PropertyCompressionSetD 1349 Practice for RubberStan
5、dard Temperatures forTestingD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsD 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2 ASTM Adjuncts:G
6、oodrich Flexometer Anvil Drawings33. Summary of Test Method3.1 The test consists of subjecting a specimen of rubber ofdefinite size and shape to rapidly oscillating compressivestresses under controlled conditions. Although heat is gener-ated by the imposed oscillating stress, the more convenientpara
7、meter, the temperature rise, is measured. The measuredtemperature rise is one of two types: (1) to an equilibriumtemperature or (2) the rise in a fixed time period. Additionalmeasured performance properties are the degree of permanentset or other specimen dimensional changes, or both, and forcertain
8、 test conditions, the time required for a fatigue failure byinternal rupture or blow out.3.2 Two test methods are covered, using the followingdifferent types of apparatus:3.2.1 Test Method AGoodrich Flexometer.3.2.2 Test Method BFirestone Flexometer.4. Significance and Use4.1 Because of wide variati
9、ons in service conditions, nocorrelation between these accelerated tests and service perfor-mance is given or implied. However, the test methods yielddata that can be used to estimate relative service quality ofdifferent compounds. They are often applicable to research anddevelopment studies.5. Prep
10、aration of Sample5.1 The sample may consist of any vulcanized rubbercompound except those generally classed as hard rubber,provided it is of sufficient size to permit preparation of the testspecimen required for the test method to be employed. Thesample may be prepared from a compound mixed experime
11、n-tally in the laboratory or taken from process during manufac-ture, or it may be cut from a finished article of commerce.5.2 If prepared in the laboratory, the procedure shouldpreferably be essentially as specified in Practice D 3182,except that when vulcanization is required, the sample shouldpref
12、erably be molded in block form of sufficient size to permitcutting of the required test specimens rather than in the form ofthe standard test slab.1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.15 on DegradationTest
13、s.Current edition approved May 1, 2007. Published May 2007. Originallyapproved in 1941. Last previous edition approved in 1999 as D 623 99e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volu
14、me information, refer to the standards Document Summary page onthe ASTM website.3Available from ASTM International Headquarters. Order Adjunct No.ADJD0623. Original adjunct produced in 1939.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St
15、ates.5.2.1 The direct molding of the specimen for Test MethodAis allowed (see 9.4) but may not yield results identical tospecimens cut from a molded block. Care must be taken inpreparation on the raw stock for direct molding of specimens.5.3 Samples from commercial articles shall consist of apiece s
16、lightly larger than the required test specimen and shallsubsequently be cut or buffed to size.5.4 Comparison of results shall be made only betweenspecimens of identical size and shape.TEST METHOD AGOODRICH FLEXOMETER46. Nature of Test6.1 In this test method, which uses the Goodrich Flexom-eter, a de
17、finite compressive load is applied to a test specimenthrough a lever system having high inertia, while imposing onthe specimen an additional high-frequency cyclic compressionof definite amplitude. The increase in temperature at the base ofthe test specimen is measured with a thermocouple to providea
18、 relative indication of the heat generated in flexing thespecimen. Specimens may be tested under a constant appliedload, or a constant initial compression. The change in height ofthe test specimen can be measured continuously during flexure.By comparing this change in height with the observed perma-
19、nent set after test, the degree of stiffening (or softening) of thetest specimen may be estimated.Anisotropic specimens may betested in different directions producing measurable differencesin temperature rise due to the anisotropy.7. Apparatus7.1 The essential parts of the apparatus are shown in Fig
20、. 1.The test specimen is placed between anvils faced with insertsof a black NEMA Grade XX Paper-Phenolic, for heat-insulation purposes. The top anvil or hammer is connected toan adjustable eccentric usually driven at 30 6 0.2 Hz (1800rpm). The static load is applied by means of a lever having afulcr
21、um point consisting of a low friction bearing cartridgeblock or resting on a knife edge. The moment of inertia of thelever system is increased, and its natural frequency reduced, bysuspending masses of approximately 24 kg (53 lb) at each endof the lever system. The lower anvil may be raised or lower
22、edrelative to the lever by means of a calibrated micrometerdevice. This device permits the lever system to be maintainedin a horizontal position during the test as determined by apointer and a reference mark on the end of the bar or a gearmotor mounted to the end of the lever system to automatically
23、drive the micrometer device based on sensors indicating thelevel position of the system. The increase in temperature at thebase of the specimen is determined by means of a thermo-couple placed at the center of the bottom anvil.7.2 The machine may be equipped with a well-insulated,temperature-control
24、led oven to permit testing at elevatedtemperatures.8. Adjustment8.1 Locate the machine on a firm foundation. Adjust theleveling screws in the base to bring the machine into a levelposition in all directions at a point just to the rear of thefulcrum of the loading lever. With the loading lever locked
25、 inplace with the pin, place a level on the lever bar and verify thelevel setting.8.2 Adjust the eccentric to give a stroke of 4.45 6 0.03 mm(0.175 6 0.001 in.) (Note 1). This is best accomplished bymeans of a dial micrometer resting on either the cross bar of theupper anvil or by means of adapters
26、attached to the loading armof the eccentric.NOTE 1The 4.45-mm (0.175-in.) stroke is selected as the standard forcalibration purposes. When strokes other than 4.45 mm (0.175 in.) are tobe used, the displacement of the lower anvil should be maintained withinthe tolerance specified for its height above
27、 the loading lever. The tolerancefor all stroke settings shall be 60.03 mm (60.001 in.).8.3 Raise the top anvil as far as the eccentric will permit byits rotation. Place a calibrating block (Note 2) 25.40 6 0.01mm (1.000 6 0.0005 in.) in height on the lower anvil. Raise theanvil by means of the micr
28、ometer until the bottom side of themetal cup holding the thermocouple is 67 6 3 mm (2.625 60.125 in.) above the top of the loading lever. The loading leveris to be in the locked position. Adjust the cross bar of the upperanvil, maintaining a parallel setting with the lower anvil and afirm contact wi
29、th the calibrating block. The micrometer shouldnow be set at zero. This may require disengagement of the geartrain nearest the vernier scale of the micrometer. Remove thecalibrating block and recheck the stroke for a 4.45-mm(0.175-in.) setting. Set the pointer on the mark on the end of thelever bar
30、to mark the level position. If equipped with acomputer system, follow the calibration procedure provided inthe software.4Lessig, E. T., Industrial and Engineering Chemistry, IENAA, AnalyticalEdition, Vol 9, 1937, pp 582-588.1Connection to eccentric which drives top anvil.2Top anvil.3Test specimen.4L
31、ower anvil.5Support for lower anvil.6Lever through which load is applied.7Calibrated micrometer device.8Bearing assembly or knife edge.9Supporting base.10Test load.11Inertia mass of 24 kg (53 lb).12Pointer and reference mark for leveling of lever.FIG. 1 Goodrich FlexometerD623072NOTE 2A suitable blo
32、ck may be made from brass having a diameterof 17.8 mm (0.7 in.). The end to be placed on the lower anvil should becounterbored for clearance of the thermocouple disk.8.4 During the initial setup of the Flexometer, remove thelocking pin from the loading lever and gently oscillate the leversystem to d
33、etermine the point of rest. If the bar does not cometo rest in approximately the level position, slowly return it to itslevel position and release. If the movement from the levelposition is observed, add or remove a slight amount of weightto the required inertia weight to obtain a balance.8.5 The ra
34、te of cyclic compression, usually 30 6 0.2 Hz(1800 6 10 rpm) is maintained by means of the adjustableshive or shives for the V-belt drive. Many systems use anelectronically controlled direct drive motor.8.6 A Type J (IC) thermocouple using 0.40 mm (0.0159 in.)wire is centered in the face of the lowe
35、r anvil. The blackNEMA Grade XX Paper-Phenolic face is backed up with ahard rubber disk. The thermocouple may be connected to arecording device. A minimum of 100 mm (4 in.) of wire shallbe retained in the oven when used at elevated temperatures.8.7 A suitable oven for measurements at elevated temper
36、a-tures may be purchased with the machine or constructed. Theinside dimensions should be approximately 100 mm (4 in.) inwidth, 130 mm (5 in.) in depth, and 230 mm (9 in.) high. Thetop of the floor of the oven shall be 25.4 6 2.5 mm (1.0 6 0.1in.) above the loading lever.8.8 The air circulation is to
37、 be maintained by a squirrel-cagetype blower 75 mm (3 in.) in diameter. The air intake shouldhave a diameter of approximately 59 mm (2.313 in.). The scrollopening for the air discharge shall be 38 by 44 mm (1.5 by 1.75in.). A motor capable of maintaining a constant rpm under loadbetween 25.8 and 28.
38、3 Hz (1550 and 1700 rpm) shall be usedfor the blower. A platform shall be provided in the base of theoven on which the specimens may be placed for conditioning.Such a platform can suitably be obtained from 6-mm (0.25-in.)wire screen netting supported at least 9 mm (0.375 in.) abovethe floor of the o
39、ven.8.9 A thermocouple of a matching type as that used in thelower anvil shall be used for measuring the ambient airtemperature. It shall be located approximately 6 to 9 mm (0.25to 0.375 in.) to the rear of the upper and lower anvils andslightly right of center. The sensing point should be at a poin
40、tabout midway between the anvils. A minimum 100 mm (4 in.)of wire should be retained within the oven.8.10 A thermostatic control shall be capable of main-taininga ambient air within 61.1C (2F) of the set point.9. Test Specimen9.1 The test specimen as prepared from vulcanized rubbershall be cylindric
41、al in shape, having a diameter of 17.8 6 0.1mm (0.700 6 0.005 in.) and a height of 25 6 0.15 mm (1.0006 0.010 in.).9.2 The standard test specimen shall be cut from a labora-tory slab, prepared in accordance with Practice D 3182. Thecured thickness shall be such that buffing is not required. See5.2.
42、A cured block approximately 76.2 by 50.8 by 25.4 mm (3by 2 by 1 in.) has been found satisfactory.9.3 The circular die used for cutting the specimen shall havean inside diameter of 17.78 6 0.03 mm (0.700 6 0.001 in.). Incutting the specimen the die shall be suitably rotated in a drillpress or similar
43、 device and lubricated by means of a soapsolution. A minimum distance of 13 mm (12 in.) shall bemaintained between the cutting edge of the die and the edge ofthe slab. The cutting pressure shall be as light as possible tominimize cupping or taper in the diameter of the specimen.9.4 An optional metho
44、d of preparing the test specimen maybe the direct molding of the cylinder.NOTE 3It should be recognized that an equal time and temperature ifused for both the slab and molded specimen will not produce an equivalentstate of cure in the two types of specimen. A “tighter” cure will beobtained in the mo
45、lded specimen. Adjustments, preferably in the time ofcure, must be taken into consideration if comparisons between the twotypes of specimen are to be considered valid.5NOTE 4It is suggested, for purposes of uniformity and closer toler-ances in the molded specimen, that the dimensions of the mold bes
46、pecified and shrinkage compensated for. A plate cavity 25.78 6 0.05 mm(1.015 6 0.002 in.) in thickness and 18.00 6 0.05 mm (0.709 6 0.002 in.)in diameter, with overflow cavities both top and bottom when combinedwith two end plates will provide one type of a suitable mold.9.5 Samples from a manufactu
47、red article shall consist of apiece slightly larger than the required test specimen and shallsubsequently be cut or buffed to size.10. Recommended Test Conditions10.1 Recommended load on the specimen is given in Table1.10.2 The stroke may be varied to provide a satisfactory testcondition in respect
48、to the load. The recommended strokes are4.45 mm (0.175 in.), 5.71 mm (0.225 in.), and 6.35 mm (0.250in.).5Conant, F. S., Svetlik, J. F., Juve, A. E., “Equivalent Cures in Specimens ofVarious Shapes” Rubber World, RUBWA, March, 1958; Rubber Age, RUAGA,March, 1958; Rubber Chemistry and Technology, RCT
49、EA, July-Sept. 1958.TABLE 1 Recommended Load on SpecimenNOTEFor calculation of masses, the long arm is 288.3 mm (11.35 in.) and the shorter arm 127.0 mm (5.0 in.).Load on Beam Load on Specimen Unit Load on SpecimenN lbf N lbf kPa psi70.5 6 0.2 15.86 6 0.03 160 36 644 93.54108.0 6 0.2 24.23 6 0.03 245 55 990 142.91216.0 6 0.2 48.46 6 0.03 489 110 1970 285.83D62307310.3 Under certain conditions, the machine may be operatedat room temperature. Precautions must be taken, however, toreturn the base thermocouple to equilibrium and to maintain auniform room temper
