Designation:D7846−12AnAmericanNationalStandardStandardPracticeforReportingUniaxialStrengthDataandEstimatingWeibullDistributionParametersforAdvancedGraphites1ThisstandardisissuedunderthefixeddesignationD7846;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticecoversthereportingofuniaxialstrengthdataforgraphiteandtheestimationofprobabilitydistributionparametersforbothcensoredanduncensoreddata.Thefailurestrengthofgraphitematerialsistreatedasacontinuousrandomvariable.Typically,anumberoftestspecimensarefailedinaccordancewiththefollowingstandards:TestMethodsC565,C651,C695,C749,PracticeC781orGuideD7775.Theloadatwhicheachspecimenfailsisrecorded.Theresultingfailurestressesareusedtoobtainparameterestimatesassociatedwiththeunderlyingpopulationdistribution.Thispracticeislimitedtofailurestrengthsthatcanbecharacterizedbythetwo-parameterWeibulldistribution.Furthermore,thispracticeisrestrictedtotestspecimens(primarilytensileandflexural)thatareprimarilysubjectedtouniaxialstressstates.1.2Measurementsofthestrengthatfailurearetakenforvariousreasons:acomparisonoftherelativequalityoftwomaterials,thepredictionoftheprobabilityoffailureforastructureofinterest,ortoestablishlimitloadsinanapplica-tion.Thispracticeprovidesaprocedureforestimatingthedistributionparametersthatareneededforestimatingloadlimitsforaparticularlevelofprobabilityoffailure.2.ReferencedDocuments2.1ASTMStandards:2C565TestMethodsforTensionTestingofCarbonandGraphiteMechanicalMaterialsC651TestMethodforFlexuralStrengthofManufacturedCarbonandGraphiteArticlesUsingFour-PointLoadingatRoomTemperatureC695TestMethodforCompressiveStrengthofCarbonandGraphiteC709TerminologyRelatingtoManufacturedCarbonandGraphiteC749TestMethodforTensileStress-StrainofCarbonandGraphiteC781PracticeforTestingGraphiteandBoronatedGra...
