1、Designation:D448211Standard Test Method forRubber PropertyExtension Cycling Fatigue1This standard is issued under the fixed designation D4482;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in paren
2、theses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of fatigue lifeof rubber compounds undergoing a tensile-strain cycle.Duringpart of the cycle,the strain is relax
3、ed to a zero value.Thespecimens are tested without intentionally initiated flaws,cuts,or cracks.Failure is indicated by a complete rupture of the testspecimen.1.2 No exact correlation between these test results andservice is given or implied.This is due to the varied nature ofservice conditions.Thes
4、e test procedures do yield data that canbe used for the comparative evaluation of rubber compoundsfor their ability to resist(dynamic)extension cycling fatigue.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.4 This standard do
5、es 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.2.Referenced Documents2.1 ASTM Standar
6、ds:2D3182 Practice for RubberMaterials,Equipment,and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3767 Practice for RubberMeasurement of DimensionsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustr
7、ies2.2British Standard:BS5324 Guide to Application of Statistics to Rubber Test-ing33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 extension ratiothe ratio of the extended length of aspecimen,L,to the unextended length,Lo,calculated asfollows:5LLo(1)3.1.2 fatigue life(sample)t
8、he geometric mean or medianvalue of the number of cycles required to cause failure for anumber of specimens of the sample.3.1.3 fatigue life(specimen)the total number of cyclesrequired to cause failure of a specimen,defined as a completerupture or separation of the specimen.3.1.4 strain energythe en
9、ergy per unit of volume requiredto deform the specimen to the specified strain.It is measuredby the area under a stress-strain curve and expressed in kJ/m3(see Annex A1).4.Summary of Test Method4.1 The dumbbell test specimens are cyclically strained at afixed frequency and a series of fixed maximum
10、extension ratiossuch that little or no temperature rise is induced.This cyclicalstraining action is called flexing.As a result of the flexing,cracks usually initiated by a naturally occurring flaw,grow andultimately cause failure which is defined as complete rupture ofthe test specimen.The number of
11、 cycles to failure(fatigue life)is recorded.4.2 Fatigue,as used in this test method,implies a rupturefailure mechanism that results from the growth of flaws in thespecimen.Fatigue does not refer to the drastic alteration of thephysical-chemical rubber structure characteristic of high fre-quency flex
12、ing tests that give rise to a substantial temperatureincrease.4.3 Fatigue life may be determined at each of a number ofdifferent extension ratios and the log(fatigue life)plotted as a1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcom
13、mittee D11.15 on Degradation Tests.Current edition approved May 1,2011.Published July 2011.Originally approvedin 1985.Last previous edition approved in 2007 as D4482 07.DOI:10.1520/D4482-11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at servicea
14、stm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from British Standards Institute,2 Park St.,London W1A 2BF,United Kingdom.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2
15、959.United States1 function of either extension-ratio or log(strain energy).Asingle extension-ratio or log(strain energy)may be used forlimited comparisons of rubber vulcanizates having similarstress-strain properties and the same polymer system(seeAnnex A1).5.Significance and Use5.1 This test metho
16、d covers one procedure for determiningfatigue life at various extension-ratios.The strain cycle ischaracteristic of the type of test apparatus specified.Experi-ence in fatigue testing shows that fatigue life may have a wide,non-normal distribution and,therefore,a large standard devia-tion that is compound dependent.Natural rubber,for example,has shown a narrower distribution than many synthetic rubbers.A large number of specimens may,therefore,be required toyield the desired precision.Comparison
