Automobiles - Vehicle_Dynamics(8)

FHRegensburg,UniversityofAppliedSciences

AgriculturalTractors, PassengerCarswithTrailer TruckTrailer/Semitrailer, RoadTrains.

Prof.Dr.-Ing.G.Rill

Forcomputercalculationsthesevehicleshavetobedepictedinmathematicallydescribablesubstitutesystems.Thegenerationoftheequationsofmotionsandthenumericsolutionaswellastheacquisitionofdatarequiregreatexpenses.

IntimesofPCsandworkstationscomputingcostshardlymatteranymore.

Atanearlystageofdevelopmentoftenonlyprototypesareavailablefor eldand/orlaboratorytests.

Resultscanbefalsi edbysafetydevices,e.g.jockeywheelsontrucks.

1.1.4Load

Trucksareconceivedfortakingupload.Thustheirdrivingbehaviorchanges.

Load

mass,inertia,centerofgravitydynamicbehaviour(liquidload)

Incomputercalculationsproblemsoccurwiththedeterminationoftheinertiasandthemod-ellingofliquidloads.

Eventheloadingandunloadingprocessofexperimentalvehiclestakessomeeffort.Whenmakingexperimentswithtanktrucks, ammableliquidshavetobesubstitutedwithwater.Theresultsthusachievedcannotbesimplytransferredtorealloads.

1.1.5Environment

TheEnvironmentin uencesprimarilythevehicle:

Environment

Road:irregularities,coef cientoffrictionAir:resistance,crosswind

→vehicle

butalsoin uencesthedriver

Environment

climate

visibility

→driver

Throughtheinteractionsbetweenvehicleandroad,roadscanquicklybedestroyed.

Thegreatestproblemin eldtestandlaboratoryexperimentsisthevirtualimpossibilityofreproducingenvironmentalin uences.

Themainproblemsincomputersimulationarethedescriptionofrandomroadirregularitiesandtheinteractionoftiresandroadaswellasthecalculationofaerodynamicforcesandtorques.

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