vehicle crashworthiness

7/30/2019 Vehicle Crashworthiness

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VEHICLECRASHWORTHINESSANDOCCUPANTPROTECTION


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MotorVehicleSafet

TheAutomobile

Structure

Materials

Crashworthiness

CrashworthinessGoals

CrashworthinessRequirements

AchievingCrashworthiness

ras wort nesstests

CrashworthinessModelRequirements


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Contents

The first motor vehicle fatalit occurred in 1889 in New

York City. An early period of safety from the turn of the century to

1935 period of genesis, growth, and development to

understanding the extremely complex process of vehicle

collisions.

The second period from 1936 to 1965 intermediate safety

period with crash avoidance devices.

The third period starts in 1966

the creation of the National

Highway Traffic Safety Administration (NHTSA).


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Currentcarbod structuresandli httrucks

body

over

frame

structure

unitbodystructure(includingspaceframe)

e c e o y External to minimize drag

accommodate its occupants

Vehicle body with the suspension to minimize road

Vehiclestructuretomaintainitsintegrityandprovideadequateprotectioninsurvivablecrashes


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BodyonFrameBodyinwhiteofaUnibody


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The ma orit of mass roduced vehicle bodies over the

last six decades were manufactured from stampedsteel components.

Until the 1920s, automakers built vehicle bodies from

a composite of wood panels joined with steel brackets. As metallurgists improved the formability of sheet steel

and toolmakers built durable dies capable of stamping

joining large body shells.

.


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Crashworthinessmeasure of the abilit of a structure

and any of its components to protect the occupants insurvivable crashes. (aerospace industry)

Crashworthiness connotes a measure of the vehicles

structural ability to plastically deform and yet maintaina su c en surv va space or s occupan s n cras es

involving reasonable deceleration loads.

additional protection to reduce severe injuries and

fatalities.


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absorb part of the crash kinetic energy.

compartment and simultaneously control the crash

deceleration ulse.

Accident reconstruction and analysis of vehicle crashes

rovide information re ardin the safet erformance.

Currently, vehicle crashworthiness is evaluated in four

distinct modes: frontal side rear and rollover crashes.


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properride

and

handling.

thatgiverisetoharshness.

Accommo ate orarangeo occupants zes,

ages,andcrashspeedsforbothgenders.


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Characteristics:

Deformable,

yet

stiff,

front

structure

with

crumple

zonestoabsorbthecrashkineticenergy.

.

Properlydesignedsidestructuresanddoorsto

minimizeintrusion.

Strongroofstructureforrolloverprotection.

Properlydesignedrestraintsystemsthatworkinharmon withthevehiclestructure.

Accommodatevarious

chassis

designs

for

different

powertrainlocationsanddriveconfigurations


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Uni ueworkofautomotivestructural

crashworthinessengineer

:

must meet all service load requirement and it mustdeform plastically in a short period of time(milliseconds) to absorb the crash energy in a

controllable manner.

must be light and be economically massproduced.

The structural stiffness must be tuned for ride and

an ing, NVH an must e compati e wit ot ervehicles on the road, so it is not too soft or tooa ressive.


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packagingthe

occupants

for decelerations

transmittedtotheoccupantsaremanageablebytheinteriorrestraintstofallwithintherangeof

human

tolerance.

u g y g reduceoccupantharm.

,combination

of

crash

avoidance

and

crashworthinessmeasures.


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in crashworthiness simulations, vehicle.

Three categories of tests:

omponen es s

Sledtests

Fullscale

barrier

impacts


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Dynamic

and/or

quasi

static

response

to

loading

.

Crucialinidentifying

Energyabsorptioncapacity

developmentofmathematicalmodelsand

.


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Vehicle

buck

passenger

compartment

Ant ropomorp ictest evicesorca avers

driversor

passenger.

Dynamicloadvehicledecelerationtimepulse

Primar ob ective toevaluaterestraints

Sensorsondummy,highspeedphotography

.


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Fullscalebarriertest:

Collision

of

aguided

vehicle,

propelled

into

abarrieratapredeterminedinitialvelocityand

.

Abarriertestusesacompletevehicle.

. Frontalimpactwithbarrierzero, 30

Unrestraineddummiesinthedriverandrightfront

passenger NCAP higherspeedimpactwithrestrained


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CrashworthinessModelsContentsRequirements

Accurac themodelshouldbeableto ieldreasonabl

accurate

predictions

of

the

essential

features

being

sought Speed themodelshouldbeexecutablewithareasonable

turnaroundtime,nottoexceed12hoursregardlessofits

size,toallowforiterationsandparameterstudies.

notyieldlargemodelresponses.

Developmenttime themodelcouldbebuiltina

reasonablyshort

period

of

time,

not

to

exceed

two

weeks

vehicle crashworthiness

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