1、Designation: D623 07 (Reapproved 2014)Standard Test Methods forRubber PropertyHeat Generation and Flexing Fatigue InCompression1This standard is issued under the fixed designation D623; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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.1. Scope1.1 These test methods may be used to compare the fatiguecharacteristics and rate of heat generation of dif
3、ferent rubbervulcanizates 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 wit
4、h 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.2. Referenced Documents2.1 ASTM Standards:2D395 Test Methods for Rubber PropertyCompression SetD1349 Practice
5、for RubberStandard Temperatures forTestingD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries2.2 AST
6、M Adjuncts:Goodrich 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 co
7、nvenientparameter, 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, an
8、d forcertain 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
9、wide variations 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 stu
10、dies.5. Preparation 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 mi
11、xed experimen-tally in the laboratory or taken from process duringmanufacture, or it may be cut from a finished article ofcommerce.5.2 If prepared in the laboratory, the procedure shouldpreferably be essentially as specified in Practice D3182, exceptthat when vulcanization is required, the sample sh
12、ould prefer-ably be molded in block form of sufficient size to permitcutting of the required test specimens rather than in the form ofthe standard test slab.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
13、 block. Care must be taken inpreparation on the raw stock for direct molding of specimens.1These test methods are under the jurisdiction of ASTM Committee D11 onRubber and are the direct responsibility of Subcommittee D11.15 on DegradationTests.Current edition approved May 1, 2014. Published May 201
14、4. Originallyapproved in 1941. Last previous edition approved in 2007 as D623 07. DOI:10.1520/D0623-07R14.2For 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 standa
15、rds Document Summary page onthe ASTM website.3Available from ASTM International Headquarters. Order Adjunct No.ADJD0623. Original adjunct produced in 1939.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.3 Samples from commercial art
16、icles shall consist of apiece slightly 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
17、 the GoodrichFlexometer, a definite compressive load is applied to a testspecimen through a lever system having high inertia, whileimposing on the specimen an additional high-frequency cycliccompression of definite amplitude. The increase in temperatureat the base of the test specimen is measured wi
18、th a thermo-couple to provide a relative indication of the heat generated inflexing the specimen. Specimens may be tested under aconstant applied load, or a constant initial compression. Thechange in height of the test specimen can be measuredcontinuously during flexure. By comparing this change inh
19、eight with the observed permanent set after test, the degree ofstiffening (or softening) of the test specimen may be estimated.Anisotropic specimens may be tested in different directionsproducing measurable differences in temperature rise due to theanisotropy.7. Apparatus7.1 The essential parts of t
20、he apparatus are shown in Fig. 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 m
21、eans of a lever having afulcrum 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
22、 anvil may be raised or loweredrelative 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
23、lever system to automaticallydrive 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-
24、insulated,temperature-controlled 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.
25、With the loading lever locked 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 a
26、nvil or by means of adapters 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 s
27、pecified for its height above 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
28、theanvil by means of the micrometer 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 low
29、er anvil and afirm contact with 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 mar
30、k on the end of thelever bar to mark the level position. If equipped with acomputer system, follow the calibration procedure provided inthe software.NOTE 2A suitable block 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
31、clearance of the thermocouple disk.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.4Lower anvil.5Support for lower anvil.6Lever through which load is applied.7Calibrated
32、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 FlexometerD623 07 (2014)28.4 During the initial setup of the Flexometer, remove thelocking pin from the loading lever and
33、gently oscillate the leversystem to determine 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
34、weight to obtain a balance.8.5 The rate 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.)wir
35、e is centered in the face of the lower 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 ove
36、n for measurements at elevated tempera-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 loadin
37、g lever.8.8 The air circulation is to 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 consta
38、nt rpm under loadbetween 25.8 and 28.3 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 m
39、m (0.375 in.) abovethe floor of the oven.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.
40、The sensing point should be at a pointabout 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 fro
41、m vulcanized rubbershall be cylindrical 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 D3182. Thecured thickness shall be such th
42、at buffing is not required. See5.2. 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 suitabl
43、y rotated in a drillpress or similar 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 o
44、f the specimen.9.4 An optional method 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 “tig
45、hter” cure will beobtained in the molded 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 closertolerances in the molded specimen, t
46、hat the dimensions of the mold bespecified 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
47、 mold.9.5 Samples from a manufactured 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 sati
48、sfactory testcondition in respect to the load. The recommended strokes are4.45 mm (0.175 in.), 5.71 mm (0.225 in.), and 6.35 mm (0.250in.).10.3 Under certain conditions, the machine may be operatedat room temperature. Precautions must be taken, however, toreturn the base thermocouple to equilibrium
49、and to maintain auniform room temperature throughout the duration of thecomplete test. The oven shall be removed when testing at roomtemperature.10.4 Tests conducted at 50C (122F) and 100C (212F)are recommended.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, RCTEA, July-Sept. 1958.TABLE 1 Recommended Load on SpecimenNOTE 1For calculation of masses, the long arm is 288.3 mm (11.35 in.) and the shorter arm 127.0
