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Passive Safety Technologies
By The Editors/autoMedia.com
Discern the definitions of systems that help you handle the unforeseen. Here's
a look at the current range of passive-safety technologies available in the
automotive arena.
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It was about 50 years ago when Newton's First Law of Motion began to be
seriously considered by the automobile industry. The law? In part, it states
that an object in motion tends to stay in motion – unless acted upon by an
outside force. Over the course of the last half-century, great scientific
research has focused on dispersing kinetic energy in a crash. The effort has
yielded such standard features as seatbelts, collapsible steering columns,
shoulder belts with emergency-locking retractors, airbags, unibody crush
zones, and other features that provide an even higher level of protection.
Here's a look at the current range of passive-safety technologies available in
the automotive arena.
Bumpers
What they are: There was a time when crude steel bumpers were the sum total of
automotive crash engineering. Found outside or inside of front and rear body
fascias, today's lightweight, sophisticated bumpers may be attached to the
unibody on metal tubes or struts, and may have shock-absorbing features such
as foam lining, deformable brackets, or other energy absorbers.
How they work: By cushioning the force of a minor impact, bumpers can help
prevent more costly damage to the vehicle bodywork and structure.
How they benefit the passengers: Bumpers are designed to help reduce vehicle
damage in a minor collision. They also function as part of the vehicle's
overall crash energy attenuation engineering. By collapsing in moderate to
severe collisions, bumpers sacrifice themselves to help protect the vehicle's
occupants.
Crumple Zones
What they are: Unibody passenger vehicles and many body-on-frame vehicles
utilize specially designed front and rear areas that crumple or deform in a
collision, helping to disperse energy.
How they work: A passenger vehicle's unibody is made of different sections of
steel (or sometimes aluminum) welded into a single monocoque or unibody
structure. Designed on computers and proven in the laboratory, special areas
at the front and back of the unibody are specifically designed to bend, fold
or otherwise deform in an accident. Body-on-frame vehicles often use a similar
strategy in their body structures.
How they benefit the passengers: Crumple zones help slow the rate of
deceleration for passengers, helping to reduce the chances of injury.
Frontal Airbags
What they are: Frontal airbags, or airbags, are inflatable cushions (bags of
inert gas) that help slow the rate of deceleration for the driver and front
passenger during a frontal collision.
How they work: The driver and front passenger's airbags are stored in
compartments in the steering wheel and instrument panel, respectively. In a
collision that exceeds a preset level of forward deceleration (determined by
crash sensors located in the vehicle), a pyrotechnic gas generator is ignited
and, in a few milliseconds, generates nitrogen gas that deploys and fills the
airbag. By the time the occupant has moved forward toward the airbag, it is
ready to cushion them.
The latest frontal airbags have dual-rate inflators that deploy at different
rates depending on the severity of the crash – faster deployment for
high-speed impacts and slower deployment for low-speed crashes. In addition,
some systems are sophisticated enough to differentiate between large and small
passengers and adjust their deployment rate to suit. Some airbags have a
two-chamber design that helps keep the passenger centered during an accident.
How they benefit the passengers: It is important to note that frontal airbags
are not a replacement for seatbelts. When used in conjunction with seatbelts,
however, they have been shown to help reduce the severity of injuries in
frontal accidents.
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