1.SAE-J2521-2013

__________________________________________________________________________________________________________________________________________SAETechnicalStandardsBoardRulesprovidethat:“ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser.”SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmayberevised,reaffirmed,stabilized,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.Copyright©2013SAEInternationalAllrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorwrittenpermissionofSAE.TOPLACEADOCUMENTORDER:Tel:[phone](insideUSAandCanada)Tel:[phone](outsideUSA)Fax:[phone]Email:[e-mail]:://(R)DiscandDrumBrakeDynamometerSquealNoiseTestProcedureRATIONALEThecurrentrevisionoftheSAEJ2521includesupdatesandchangesto(a)accommodateformoderntestingtechnologies,(b)improvethesquealnoiseevaluationmatrixesfordiscanddrumbrakes,(c)bringthedocumentintothenewSAEformatstandard,(d)reviseitsformattingforclearertestsequences,and(e)improveandharmonizedefinitions,noiseevaluation,testsetupandconditions,testinertiacalculations,anddataanalysiswithotherSAEdynamometertestproceduresandrecentstandardsanddevelopmentsfromtheEKB/VDAworkinggroupsinEurope.Lastly,thisrevisionuseslowerfinaltemperaturesduringthefadesectionstobetterrepresentvehicle-leveltestingwhileofferingamoreseverefadescheduleasoptional.FOREWORDIntheearly1990saEuropeanworkinggroupincludingcarmanufacturers,brakingsystemsuppliers,andfrictionmaterialcompanies,developedadynamometertestprocedureknownastheAKNoise.Thisprocedureusestwomainmodes(a)dragmodeatlowspeedwithapressureapplicationprofilemeanttoinduceinstabilityandsquealnoise,and(b)decelerationbrakingatmoderatespeedsatconstantbrakepressure;acommonapproachintheU.S.,emphasizingthereplicationofvehicleroadtest.TheSAEJ2521combinesbothbrakingmodestosatisfythestrongneedforaglobalstandardizationofsquealnoisedynamometertests.ThisprocedurewasfirstpresentedtotheSAEworkinggroupin1999.ThisprocedureowesmuchtothepreviousdevelopmentoftheAKprocedures.Thispriorworkisgratefullyacknowledged.Bothtestmatrixes(discanddrum)includethreemainschedules:—ScheduleA-standard:standardtestsectionswithdeceleration,drag,andforward/reversesectionsatvarioustemperaturesandspeeds.—ScheduleB-optional:noiseduringcoldmodulestoassessnoisepropensitybelow50°Candatorbelowfreezinglevelofzerodegrees(0°C).—ScheduleC-optional:noiseafterfadetoassesstheinfluenceofhigh-temperatureexcursionsonthenoisepropensityofagivenbrake.Thisrecommendedpracticeestablishestheminimumstandardsetofspecificationsregardingtestsetup,inertia-dynamometercharacteristics,testsequence,andtestreportitems.Deviationsfromorchangestothisproceduretoaccommodateaspecificprojectarefeasibleaslongastheyarediscussedandagreeduponamongtheinterestedpartiespriortocommencingtheactualstagingandthetestingactivities.DownloadedfromSAEInternationalbyZhejiangUniv,Saturday,May23,2015SAEJ2521RevisedAPR2013Page2of44TABLEOFCONTENTS1.SCOPE..........................................................................................................................................................32.REFERENCES..............................................................................................................................................43.DEFINITIONS...............................................................................................................................................54.TESTEQUIPMENT.......................................................................................................................................65.TESTFIXTURE.............................................................................................................................................86.TESTINERTIA............................................................................................................................................107.PARTSPREPARATIONANDTESTSETUP..............................................................................................108.TESTCYCLES............................................................................................................................................129.TESTSEQUENCESNOMENCLATURE....................................................................................................1710.DISCBRAKETESTPARAMETERSANDTESTMATRIX.........................................................................1711.DRUMBRAKETESTPARAMETERSANDTESTMATRIX...........................