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1、Designation:D6992?03(Reapproved2015)StardTestMethodfAcceleratedTensileCreepCreepRuptureofGeosyntheticMaterialsBasedonTimeTemperatureSuperpositionUsingtheSteppedIsothermalMethod1ThisstardisissuedunderthefixeddesignationD6

2、992thenumberimmediatelyfollowingthedesignationindicatestheyearofiginaladoptioninthecaseofrevisiontheyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethel

3、astrevisionreapproval.1.Scope1.1ThistestmethodcoversacceleratedtestingftensilecreeptensilecreeprupturepropertiesusingtheSteppedIsothermalMethod(SIM).1.2Thetestmethodisfocusedongeosyntheticreinfcementmaterialssuchasyarnsr

4、ibsofgeogridsnarrowgeotextilespecimens.1.3TheSIMtestsarelaterallyunconfinedtestsbasedontimetemperaturesuperpositionprocedures.1.4TensiletestsaretobecompletedbefeSIMteststheresultsareusedtodeterminethestresslevelsfsubsequ

5、entSIMtestsdefinedintermsofthepercentageofUltimateTensileStrength(TULT).AdditionallythetensiletestcanbedesignedtoprovideestimatesoftheinitialelasticstraindistributionsappropriateftheSIMresults.1.5RampHold(RH)testsmaybeco

6、mpletedinconjunctionwithSIMtests.TheyaredesignedtoprovideadditionalestimatesoftheinitialelasticinitialrapidcreepstrainlevelsappropriateftheSIMresults.1.6Thismethodcanbeusedtoestablishthesustainedloadcreepcreepruptureacte

7、risticsofageosynthetic.ResultsofthismethodaretobeusedtoaugmentresultsofTestMethodD5262maynotbeusedasthesolebasisfdeterminationoflongtermcreepcreeprupturebehaviofgeosyntheticmaterial.1.7ThevaluesstatedinSIunitsaretoberega

8、rdedasstard.Nootherunitsofmeasurementareincludedinthisstard.1.8Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstardtoestablishappropriatesafetyhealthprac

9、ticesdeterminetheapplicabilityofregulatylimitationspritouse.2.ReferencedDocuments2.1ASTMStards:2D2990TestMethodsfTensileCompressiveFlexuralCreepCreepRuptureofPlasticsD4439TerminologyfGeosyntheticsD4595TestMethodfTensileP

10、ropertiesofGeotextilesbytheWideWidthStripMethodD5262TestMethodfEvaluatingtheUnconfinedTensionCreepCreepRuptureBehaviofGeosynthetics3.Terminology3.1FdefinitionsrelatedtogeosyntheticsseeTerminologyD4439.3.2Fdefinitionsrela

11、tedtocreepseeTestMethodsD2990D5262.3.3DefinitionsofTermsSpecifictoThisStard:3.3.1creepmodulus—inSIManalysistheloaddividedbythepercentstrainatanygivenpointintime.3.3.2dwelltime—timeduringwhichconditions(particularload)are

12、heldconstantbetweentemperaturesteps.3.3.3meantesttemperature—thearithmeticaverageofalltemperaturereadingsoftheatmospheresurroundingthetestspecimenfaparticulartemperaturestepstartingatatimenotlaterthanestablishedtemperatu

13、reramptimefinishingatatimejustpritothesubsequenttemperaturereset.3.3.4offsetmodulusmethodpointing—dataanalysismethodusedtonmalizeanyprestraininthesamplesbyshiftingtheiginofastressversusstraincurvetoanaxisiginofcodinatest

14、hatistocodinates(00).3.3.5ramphold(RH)test—acreeptestofveryshtdurationfexample100to1000s.1ThistestmethodisunderthejurisdictionofASTMCommitteeD35onGeosyntheticsisthedirectresponsibilityofSubcommitteeD35.02onEndurancePrope

15、rties.CurrenteditionapprovedMay12015.PublishedJune2015.iginallyapprovedin2003.Lastpreviouseditionapprovedin2009asD6992–03(2009).DOI:10.1520D699203R15.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustomer

16、Serviceat.FAnnualBookofASTMStardsvolumeinfmationrefertothestard’sDocumentSummarypageontheASTMwebsite.Copyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohockenPA194282959.UnitedStates1ofthematerial.Howevercrela

17、tionbetweennarrowgeotextilestripssinglegeogridribstowiderrepresentativespecimensshouldbeestablished.8.4Thelengthofthetestspecimenisdeterminedbythetypeofgripused.Refertospecifictensiletestprocedurefguidance.8.5NumberofTes

18、ts:8.5.1AsinglespecimenisusuallysufficienttodefineamastercreeprelaxationcurveusingtheSIM.HoweverifonlyasingleSIMtestistobeperfmedthelocationoftheonsetofcreepstrainmoduluscurveshouldbeconfirmedusingatleasttwoshttermcreep(

19、RH)tests.8.5.2Generally12to18specimensareneededtodefineastressrupturecurverepresentingmultiplerupturetimes.FewerspecimenswouldbeneededtodefineaspecificregionofthecurvefexamplethepercentTULTat1106h(=110year)rupturelife.9.

20、Conditioning9.1TensileSIMtestingshallbeconductedusing2061Casthereferencetemperaturestard.Ifthelabatyisnotwithinthisrangeperfmtensiletestsinasuitableenvironmentalchambercapableofcontrolledcoolingheating.Theenvironmentalch

21、ambershouldhaveaprogrammablesetpointcontrollersoastomaintaintemperatureto2061C.Whenagreedtoareferencetemperatureotherthan20Ccanbeutilized.Alsowhenagreedtotheresultsoftestingunderthisstardcanbeshiftedfromonereferencetempe

22、raturetoanother.9.2Allowthespecimenadequatetimetocometotemperatureequilibriuminthelabatyenvironmentalchamber.Generallythiscanbeaccomplishedwithinafewhours(seeNote3).9.3Recdtherelativehuityinthelabatyenvironmentalchamberf

23、alltests.10.ionofTestConditions10.1Thestardenvironmentftestingisdrysincetheeffectofelevatedtemperatureistoreducethehuityofambientairwithoutspecialcontrols.10.2Thestardreferencetemperatureis20Cunlessotherwiseagreedto.Thei

24、ndividualreferencetemperaturefeachSIMtestistheaverageachievedtemperatureofthefirstisothermaldwell.10.3Testingtemperaturesaretobewithin62Cofthetargettesttemperatures.Itiscriticallyimptantthatthetestspecimenhasequilibrated

25、throughoutitsthicknesssoastoavoidnonisothermalconditions.Initialtrialsarenecessarytoestablishthisminimumequilibriumtime.NOTE3—Labatyexperiencehassuggestedthattheuseofcalibratedthermocoupleslocatednearaffixedtoembeddedwit

26、hinthetestspecimenmayfacilitateasuccessfultemperaturecompliancetestfthespecimenmaterial.ItissuggestedthatthelabatyperfmtheplannedSIMtemperaturestepsusinganunloadedsacrificialtestspecimenwiththeuseofthesethermocouplesmeas

27、urethetemperaturechangeofthespecimenatitsthickestmostmassdenseregion.Thetimerequiredfthespecimentoreachthetargettemperatureisrecdedusedastheminimumdwelltime.Theupperlimitofthetemperatureramptimeisnotknown.Successfultests

28、withsomematerialshavebeenrunwithtemperatureramptimesofuptofourminutes.10.4Testtemperaturesaretobemaintainedwithin61.0Cofthemeanachievedtemperature.10.4.1Temperaturestepsdwelltimesmustbesuchthatthesteadystatecreeprateatth

29、ebeginningofanewstepisnotsodifferentfromthatofthepreviousthatitcannotbeestablishedwithintheidentifiedramptime.11.Procedures11.1ThesamesimilarloadstraincontrolshallbeappliedtothetensileteststheloadrampptionofRHSIM(creepcr

30、eeprupture)tests.Theloadratecontrol(inunitsofkNpermin)thatisappliedshallachieveanarrowrangeofstrainratesexpressedinpercentperminuteasagreedupon.Generally1063%permin(2063%perminfEuropeanpractice)willbesatisfacty.NOTE4—Ali

31、nearrampofloadversustimewillnotgenerallyresultinalinearstrainversustimerelationshipbecausestressversusstraincurvesarenotlinearfmostgeosyntheticmaterials.11.2AchievethetestloadsfRHSIMtestswithin62%ofthetargetloadsmaintain

32、anyachievedloadwithin60.5%ofitsvaluesfthedurationofthetest.Abriefovershootofthetargetloadthatiswithin62%ofthetargetloadlimitedtoa1to2stimedurationisacceptablefloadcontrolsystems.11.3ReplicatetestloadsfRHSIMtestsshouldbew

33、ithin60.5%oftheaverageoftheachievedloadsfatestset.11.4Pretensioningupinaccdancewiththegoverningtensiletestisacceptable.Themethodusedtodefinezerostrainistobeidentifiedrepted.11.5ThesamesimilargripsshallbeusedftensileRHSIM

34、tests.Careshouldbetakentousegripsthatdonotinitiatefailureincurslippageatstresslevelswhichmayproducespecimenrupture(fexampleatloadsgreaterthan55%ofTULTfpolyester).11.6Inspectgripstoinsureloadingsurfacesarecleanthatpadding

35、ifusedisfreeofdefectsissecuredproperly.11.7Inspectthespecimeninstallationtobesurethematerialisproperlyalignedwiththegripswiththeloadingaxis.11.8Insurethattheloadcellusediscalibratedproperlysuchthatitwillaccuratelymeasure

36、therangeoftensileloadsanticipated.11.9Insurethattheextensometerused(ifany)iscalibratedproperlysuchthatitwillaccuratelymeasuretherangeoftensilestrainsanticipated.Ifruptureisanticipatedtakeprecautionstoinsurethattherupture

37、eventwillnotdamagetheextensometercreateahazardfthemachineoperat.11.10Unlessotherwiseagreedupona100mmgaugelengthshallbeusedfgeosyntheticproductsa250to300mmgaugelengthshallbeusedfprecursyamproducts.11.11Timeloadextensionda

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