FMVSS 208 II 乘员碰撞保护

UPDATEDREVIEWOFPOTENTIALTESTPROCEDURESFORFMVSSNO.208PreparedByTheOFFICEOFVEHICLESAFETYRESEARCHWILLIAMT.HOLLOWELLHAMPTONC.GABLERSHELDONL.STUCKISTEPHENSUMMERSJAMESR.HACKNEY,NPSOCTOBER1999:MY1998BagsvsPre-MY1998Bags,ComplianceMargins.....A-1AppendixBValidationofSimulatedCrashConditions............B-1AppendixCMaximumCrushDisplacementvsLinearStiffness.....C-1(FMVSS)No.208istomeasurehowwellapassengervehiclewouldprotectitsoccupantsintheeventofaseriousrealworldfrontalcrash.Thisissometimesreferredtoasthecrashworthinessofavehicle.Thisreportreviewspotentialtestproceduresforevaluatingfrontalcrashworthiness.Structuraldesignforcrashworthinessseekstomitigatetwoadverseeffectsofacrash–(1)rapiddecelerationoftheoccupantcompartment,and(2)crushoftheoccupantcompartmentsurvivalspace.Inaseverecrash,thespeedofavehicleoftendecreasesfromitstravelspeedtozeroinahundredthousandthsofasecond.Oneimportantwaytominimizetheinjuryconsequencesofthisabruptchangeinvelocityistoextendtheamountoftimenecessarytoslowthevehicledown–thelessabruptthechangeinvelocity,thelowerthecrashforcesontheoccupant.Thefrontendofvehiclesaredesignedtocrumpleinacontrolledmannerinacollisiontogivetheiroccupantsthenecessaryadditionaltimetosafelydecelerateinacrash.Notethatthecontrolledcrushorcrumpleofthefront-end,asafetypositivefeature,istotallydifferentfromthecrushorcollapseoftheactualoccupantcompartment–whichistobeavoided.Ataminimum,partialcollapseofthestructuralcagewhichsurroundstheoccupantallowsvehicleparts(e.g.,theengineorsteeringmechanism)to“intrude”intotheoccupantspaceandstriketheoccupantcausinginjury.Inextremelyseverecollisions,theoccupantcompartmentmaysufferacatastrophiccollapse,andallowtheoccupanttobecrushed.Thedegradationoftheoccupantcompartmentsurvivalspaceismeasuredbyintrusion.Theoccupantcompartmentdecelerationseverityismeasuredbytheamplitudeandtimedurationofthedecelerationtimehistory.Thedecelerationtimehistoryissometimescalledthecrashpulse.Botheffectshavethepotentialforcausinginjury.ObjectivesTheidealfrontalcrashtestprocedurewillbeabletoevaluateoccupantprotectionwhileensuringthatthevehiclewillnotjeopardizeitscrash“friendliness”withitscollisionpartners.Thetestconditions(e.g.,impactspeed,impactangle,andtestdevice)mustberepresentativeofthefrontalcrashenvironmenttowhichpassengervehiclesareexposedonthehighway.Finally,toprovideassuranceofprotectioninpotentiallyseriousinjurycrashes,thetestproceduresmustbesevereenoughtorepresentacrashinwhichoccupantscouldbeseriouslyinjuredorkilled.