Michalec, Christopher Ryan (2005-08). Development of an optimal impact energy absorber for highway crash cushions. Master's Thesis. Thesis uri icon


  • 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.

publication date

  • August 2005