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Description:
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The objective of this research is to develop a new and efficient method of
absorbing a vehicle ? ?s kinetic energy for highway safety crash cushions . A
vehicle that makes a direct impact with a rigid highway structure traveling at
highway speeds can be fatal for its occupants . Crash cushions are implemented
on roadways in front of these rigid structures with the intent to ? ?soften ? ? the
impact . The cushion will bring a vehicle to a stop at safe rates before it impacts
the rigid structure . The energy absorbing component of the crash cushion must
meet four main requirements . The cushion must reduce the vehicles speed at a
rate that does not allow the occupant to impact the vehicle interior at velocities
greater than 12 m /s . The cushion must then bring the vehicle to a complete stop
with deceleration rates below 20 g ? ?s . A crash cushion must satisfy these
requirements for an 820 kg vehicle and a 2000 kg vehicle traveling at 100 km /hr .
Advanced design methodologies were applied to enable multiple ,
innovative design concepts . These concepts made use of the deformation of
steel in structural pipe , structural angle , and structural plate to reduce the
velocity of a vehicle at a safe rate . Critical design parameters were identified
which allowed for efficient and effective numerical experiments to be conducted .
The data collected from these experiments were then validated when compared
to physical test data . After the data had been collected , each of the designs was
compared to one another in order to decide upon the best design . The design
selected was the deforming plate concept which makes use of steel plate
mounted in a fashion that created two arms that acted similar to two cantilever
beams . A wedge was forced beneath these arms deforming them upward . This design is effective because the deformation can be easily controlled by the
thickness of the plate , the moment arm created by the wedge , and the geometry
of the wedge . Steel plate is a readily available material that requires minimal
manufacturing for installation preparation making it cost -effective , and easy to
install . In the event of impact with the cushion , new parts will be inexpensive
and readily available . Being reusable , easy to repair and low in cost , the energy
absorbing concept presented herein is a cost effective alternative to existing
energy absorbing technology . Due to replaceable parts being readily available ,
repair time and cost will be reduced compared to other designs that require new
parts to be fabricated for replacement . This will make for a competitive design . |