saej670v002

__________________________________________________________________________________________________________________________________________SAETechnicalStandardsBoardRulesprovidethat:“ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser.”SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmaybereaffirmed,revised,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.Copyright©2008SAEInternationalAllrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorwrittenpermissionofSAE.TOPLACEADOCUMENTORDER:Tel:877-606-7323(insideUSAandCanada)Tel:724-776-4970(outsideUSA)Fax:724-776-0790Email:CustomerService@sae.orgSAEWEBADDRESS:http://www.sae.orgJ670JAN2008SURFACEVEHICLERECOMMENDEDPRACTICEIssued1952-07Revised2008-01SupersedingJ670eJUL1976(R)VehicleDynamicsTerminologyRATIONALESAEJ670waslastupdatedover30yearsago.Sincethelastrevision,thefieldofvehicledynamicshaschangedsignificantly.Newsystemssuchasfour-wheelsteeringandactivecontrolhavebeenappliedtoenhancetheperformanceofvehicles.Theterminologyforvehicledynamicsneededtobeupdatedtoaccommodatethesenewtechnologiesandtomakethedefinitionsconsistentwithcurrentusageinthefield.Accordingly,manynewtermshavebeenaddedtotheterminologytoprovideformaldefinitionsfortermsthatareassociatedwiththesenewtechnologies.Anumberofexistingdefinitions,whichwerebasedonfront-wheelsteervehicleswithpassivecontrol,werealsorevisedtoaccommodatenewtechnologies.Inaddition,newSAEandISOstandardshavebeenpublishedsincethelastrevisionofSAEJ670thatdirectlyrelatetotopicsconsideredinSAEJ670.ThecontentofthesenewstandardsalsoindicatedtheneedtoreviseSAEJ670.Specifically,in1987,SAEpublishedJ1594,containingaerodynamicsterminologypreviouslyappearinginSAEJ670e.TheaerodynamicssectionofSAEJ670eisnotincludedinthereviseddocument,becausethosetermsarenowdefinedinSAEJ1594.In1991,theInternationalOrganizationforStandardization(ISO)publishedavehicledynamicsvocabulary,ISO8855.SAEJ670eandISO8855areincompatibleinseveralaspects,themostnotablebeingtheaxissystemsdefinedinthetwodocuments.SAEJ670eutilizesanaxissystembasedonaeronauticalpractice,withpositiveXforward,positiveYtotheright,andpositiveZdown.ISO8855utilizesanaxissystemwithpositiveXforward,positiveYtotheleft,andpositiveZup.TherevisedSAEJ670embracesbothoftheseaxisorientations.TherevisedSAEJ670additionallyaddressestechnicalshortcomingsfoundinbothSAEJ670eandISO8855andisaharmonizedsupersetofthetwodocuments.In1998,SAEpublishedJ2047,containingdefinitionsfortireperformancetermsthatwerepreviouslydefinedinSAEJ670e.TherevisedSAEJ670utilizesmanydefinitionsexcerptedfromSAEJ2047,althoughsomeofthesedefinitionsarerevisedtoenhancetheirapplicabilitytovehicledynamics.SeveralofthesectionsofSAEJ670edealingwithvibrationterminologyarenotincludedinthenewSAEJ670,asthetermsthatweredefinedinthesesectionsarecommonlydefinedinengineeringtextbooksandthedefinitionsarenotspecifictovehicledynamics.Finally,theterminologyisextendedtoincludedefinitionsformanysuspensionandsteeringcomponents,toenhancecommunicationamongvehicledynamicsprofessionals.ThisseventheditionofSAEJ670replacestheprecedingedition(SAEJ670e)initsentirety.SAEJ670RevisedJAN2008-2-FOREWORDThisterminologyisintendedtobesufficienttoallowmeaningfulcommunicationbetweenvehicledynamicsprofessionalswhoneedtodescribethestaticanddynamiccharacteristicsofautomobiles,lighttrucks,andtrailers.Theterminologyistobeusedforpresentingresultsandfindingsconcerningthelongitudinal,lateral,verticalandrotationaldynamicperformanceoftheapplicablevehiclesaspredictedbyanalysesandsimulationsorasmeasuredintestsandoperationalsituations.Thepurposeofthisterminologyisnottocoveralltermsinthemannerofadictionaryortermsfoundinabasicengineeringtextbook.Rather,thisdocumentcontainscompatibledefinitionsthathavebeencarefullyselectedtoaidinconveyingideaswithrigorandaccuracyinareadilyunderstoodandgenerallyacceptablemanner.TheterminologydrawsupontermsanddefinitionspreviouslyappearinginSAEJ670eandISO8855andfurtherdevelopsthosethatareapplicabletothesubjectscoveredbythisdocument.Forapplicationtothestudyofvehicledynamics,thetireterminologyinthisdocumentcontainspertinentdefinitionsextractedfromorbaseduponSAEJ2047.Definitionsformanychassiscomponentsarealsoprovided.Manyofthedefinitionsinthedocumentcontaintermsappearinginitalicfont.Definitionsfortermsinitalicmaybefoundelsewhereinthedocument.INTRODUCTIONISO8855:1991istheinternationalstandardcorrespondingtoSAEJ670.Thescopesofthesetwostandardsaredifferent.ThescopeofSAEJ670islimitedtopassengercarsandlighttruckswithtwoaxles,plusthosevehiclesincombinationwithsingle-axletrailers.ThescopeofISO8855additionallyincludesheavycommercialvehicles,withmultipleaxlesandmultipleunits.SAEJ670recognizesaxissystemswithbothZ-UpandZ-Downorientations,whileISO8855onlyrecognizestheZ-Uporientation.SAEJ670definesfiveaxissystems:Earth,intermediate,vehicle,tire,andwheel,whileISO8855definesfouraxissystems:Earth,intermediate,vehicle,andwheel(equivalenttotheSAEJ670tiresystem).SAEJ670accommodatesfour-wheelsteering,whileISO8855doesnot.SAEJ670accommodatesaninclinedroadsurfacethatisnon-uniform,whileISO8855islimitedtoapplicationonaflat,horizontalroadsurface.SAEJ670includesdefinitionsformanysuspensionandsteeringcomponents,whilecomponentdefinitionsarenotincludedinISO8855.SAEJ670alsodefinesmanymoreterms(over600)thanaredefinedinISO8855(approximately130).SAEJ670RevisedJAN2008-3-TABLEOFCONTENTSRationale.......................................................................................................................................................1Foreword.......................................................................................................................................................2Introduction...................................................................................................................................................21.Scope............................................................................................................................................................62.References....................................................................................................................................................62.1ApplicablePublications.................................................................................................................................62.1.1SAEPublications...........................................................................................................................................62.1.2ISOPublications............................................................................................................................................62.2RelatedPublications.....................................................................................................................................62.2.1SAEPublications...........................................................................................................................................62.2.2ISOPublications............................................................................................................................................72.2.3OtherPublications.........................................................................................................................................73.AxisandCoordinateSystems.......................................................................................................................84.Vehicle........................................................................................................................................................124.1GeometryandMasses................................................................................................................................124.2Kinematics...................................................................................................................................................144.2.1TranslationalMotionVariables....................................................................................................................144.2.1.1Velocities.....................................................................................................................................................154.2.1.2Accelerations...............................................................................................................................................154.2.2AngularMotionVariables............................................................................................................................164.2.2.1Angles.........................................................................................................................................................164.2.2.2AngularVelocities.......................................................................................................................................184.2.2.3AngularAccelerations.................................................................................................................................194.2.3VehicleTrajectoryMeasures......................................................................................................................194.3ForcesandMoments..................................................................................................................................204.3.1Forces.........................................................................................................................................................204.3.2Moments.....................................................................................................................................................205.SuspensionandSteering............................................................................................................................215.1GeneralNomenclature................................................................................................................................215.2SuspensionComponents............................................................................................................................215.3SteeringComponents.................................................................................................................................225.4MassesandInertias....................................................................................................................................245.5Geometry....................................................................................................................................................255.5.1SteerandCamberAngles...........................................................................................................................255.5.2Steering-AxisGeometry..............................................................................................................................275.6SuspensionMotions....................................................................................................................................285.7Kinematics...................................................................................................................................................295.7.1RideKinematics..........................................................................................................................................295.7.2RollKinematics...........................................................................................................................................305.7.3SteeringKinematics....................................................................................................................................315.7.4Anti-Characteristics....................................................................................................................................325.8RideandRollStiffness................................................................................................................................325.9Compliances...............................................................................................................................................335.9.1CamberandSteerCompliances.................................................................................................................335.9.2OtherCompliances.....................................................................................................................................34SAEJ670RevisedJAN2008-4-6.Brakes.........................................................................................................................................................346.1GeneralNomenclature................................................................................................................................346.2BrakeComponents.....................................................................................................................................346.3BrakeProportioning....................................................................................................................................357.TiresandWheels........................................................................................................................................357.1WheelNomenclature..................................................................................................................................367.2PneumaticTireNomenclature....................................................................................................................367.3WheelPlaneGeometry...............................................................................................................................377.4TireOrientationAngles...............................................................................................................................387.5TireRollingCharacteristics.........................................................................................................................387.6WheelSpinandTireSlip............................................................................................................................397.7StandardLoadsandInflationPressures.....................................................................................................397.8WheelTorque..............................................................................................................................................407.9TireForcesandMoments...........................................................................................................................407.10PullForcesandMoments...........................................................................................................................437.11PropertiesofForcesintheRoadPlane......................................................................................................467.12NormalForceProperties.............................................................................................................................477.13MomentProperties......................................................................................................................................477.14Tire/RoadFriction........................................................................................................................................488.StatesandModes.......................................................................................................................................498.1Equilibrium..................................................................................................................................................498.2Stability........................................................................................................................................................498.3ControlModes.............................................................................................................................................499.InputsandResponses................................................................................................................................509.1Inputs..........................................................................................................................................................509.2Responses..................................................................................................................................................5110.VehicleLongitudinalResponse..................................................................................................................5310.1LongitudinalLoadTransfer.........................................................................................................................5310.2DescriptorsofSteady-StateLongitudinalResponse..................................................................................5310.2.1GainMeasures............................................................................................................................................5310.2.2GradientMeasures.....................................................................................................................................5310.3DescriptorsofTransientLongitudinalResponse........................................................................................5310.4DescriptorsofTransientBrakeSystemResponse.....................................................................................5310.5CharacterizingDescriptorsofBrakingPerformance..................................................................................5411.VehicleLateralResponse...........................................................................................................................5411.1LateralLoadTransfer..................................................................................................................................5411.2RangesofDirectionalResponse................................................................................................................5411.3DescriptorsofSteady-StateDirectionalResponse....................................................................................5411.3.1GainorSensitivityMeasures......................................................................................................................5411.3.2GradientMeasures.....................................................................................................................................5511.3.3UndersteerandOversteer..........................................................................................................................5611.3.4StabilityMeasures.......................................................................................................................................5811.3.5CharacterizingSpeeds................................................................................................................................5811.4DescriptorsofTransientDirectionalResponse..........................................................................................5911.4.1Rise-TimeMeasures...................................................................................................................................5911.4.2OvershootMeasures...................................................................................................................................5911.4.3OtherTransientMeasures..........................................................................................................................6011.5DescriptorsofLimitResponse.................................................................................................................