Search Results

Rollover accidents account for a large number of serious to fatal injuries annually. In the past, these injuries were often the result of unrestrained occupant ejection. Subsequent to mandatory belt use laws, a larger percentage of these injuries occur inside the vehicle, and the head and neck areas sustain a substantial number of these injuries. Rollovers have been characterized as violent events, roof crush as the natural consequence of such violence. Further, head and neck injury have been thus considered unavoidable, even with occupant use of the production restraints. This paper will describe the relationship between the three dimensional extent (severity) of roof crush and the equivalent drop test contact velocity as derived from physical experiments and tests. The drop test contact velocity is directly related to the cumulative change of velocity experienced by a vehicle as a result of roof contact deformation during a rollover accident by validated computer simulations.

Inverted drop testing of vehicles is a methodology that has long been used by the automotive industry and researchers to test roof integrity. In our laboratory, the inverted drop test methodology was employed on late model production vehicles to simulate the damage incurred by a real world rollover accident. The extent and shape of residual damage matched well with the corresponding accident damage. Modified vehicles were reinforced based upon previously documented techniques. Incorporation of these techniques demonstrated a significant increase in roof strength and corresponding reduction in roof crush with minor weight addition. Finally, a production vehicle and structurally enhanced vehicle were drop tested with instrumented Hybrid-III occupants. This pair of tests confirms that reduction of roof intrusion and increased headroom can significantly enhance occupant protection. It also highlights the need to maintain adequate survival space for the vehicle’s occupants.

In this study we continue and build upon previous research conducted with various production three-point restraint systems; studying resulting vertical excursion on restrained inverted occupants. Vertical excursions will be reported for various sized occupants restrained by both production vehicle belt systems as well as systems incorporating alternative designs. Vertical excursions have been reduced by an average of 77% with optimized belt geometry combined with belt pretensioning.

Accident reconstruction analysis of both pre- and post-impact vehicle trajectory wherein an involved vehicle has collided with or traversed a roadside curb often leaves the analyst with uncertainty associated with the speed loss and accelerations attributable to these impacts. A review of available published data reveals very few studies considering the energy dissipated and transferred to the vehicle's occupants. This paper quantifies the changes in vehicle velocity (delta-v) for various vehicles traversing a typical roadside curb at various approach angles and impact speeds. Vehicle accelerations are recorded in the vertical, longitudinal, and lateral directions. Resulting three-point belted driver movements are observed via an interior mounted video camera and general occupant motions are described. Curb impacts were conducted with four different passenger vehicles ranging in size from a small compact car to a large full-size sport utility vehicle.