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Much has been written about reconstruction techniques and testing methods concerning vehicle rollovers. To date, most of the literature describes rollovers as one-dimensional events. Rollovers account for a disproportionate fraction of serious injuries and fatalities among all motor vehicle accidents. The three-dimensional nature of rollover sequences in which a rolling vehicle experiences multiple ground contacts contributes to the environment where such injuries occur. An analytical technique is developed to model the airborne segments of a rollover sequence as a parabolic path of the vehicle center of gravity. A formulation for the center of gravity descent from maximum elevation to full ground contact is developed. This formulation contains variables that may be readily determined from a thorough reconstruction. Ultimately, this formulation will also provide a vertical ground impact velocity at contact.

Most rollover literature is statistical in nature, focuses on reconstructed field data and experiences, or utilizes a very broad pool of dissimilar test data. When test data is presented, nearly all of it involves hard surface rollover tests performed at speeds near 30 mph, with a mix of passenger cars, sport utility vehicles and minivans. Five full-scale dolly rollover tests on dirt of production sport utility vehicles (SUV) and multi-purpose vehicles (MPV) were performed with similar input parameters. The similarities included Federal Motor Vehicle Safety Standard (FMVSS) 208 rollover dolly initiated events, level dirt rollover surfaces, and initiation speeds over 40 mph. All tests were recorded with multiple high-speed and real-time cameras. Additionally, some of the tests included detailed documentation of the rollover surface and the resulting evidence and debris patterns, as well as onboard angular rate sensing instrumentation.

Research focusing on automotive rollovers has garnered a great deal of attention in recent years. Substantial effort has been directed toward the evaluation of rollover resistance. Issues related to crashworthiness, such as roof strength and restraint performance, have also received a great deal of attention. Much less research effort has been directed toward a more detailed study of the rollover dynamics from point-of-trip to point-of-rest. The reconstruction of rollover crashes often requires a thorough examination of the events taking place between point-of-trip and point-of-rest. Increasing demands are placed on reconstructionists to provide greater levels of detail regarding the roll sequence. Examples include, but are not limited to, roll rates at the quarter-roll level, CG trajectory (horizontal and vertical), roll angle at impact, and ground contact velocity. Often the detail that can be provided in a rollover reconstruction is limited by a lack of physical evidence.

This paper presents a detailed analysis and reconstruction of a real-world, high-speed yaw and rollover of a sport utility vehicle that occurred on paved and unpaved surfaces with uneven topography. A law enforcement videotape of the crash, along with detailed inspection and measurement of the subject vehicle and accident site, enabled quantitative analysis of the event. The physical evidence was correlated with video images of the real-world rollover to obtain detailed information of the rollover mechanics throughout the sequence. The initial speed of the vehicle was 79 mph and its speed at overturn was 54 mph. The vehicle rolled six revolutions. The average roll rate for the entire sequence was more than 300 degrees/second, with peak values approaching 540 degrees/second. The rollover deceleration was found to be non-uniform during the sequence, and ranged from approximately 0.6 g to 0.2 g.

Reconstruction of motor vehicle collisions using impulse center-based impulse-momentum formulations is commonly accomplished using computer codes to solve the conservation equations assuming instantaneous momentum exchange. Some models accommodate finite duration, or non-instantaneous impulses. This paper describes an impulse-momentum with impulse center, graphical-input computer code designed with selectable pulse width to better simulate real-world collisions compared with solutions based on instantaneous momentum exchange. This paper presents a more realistic approach to the momentum formulation using an impulse center by applying a finite duration, rectangular crash pulse to obtain modeling results that are then compared to the instantaneous momentum exchange approach. Detailed comparisons with two crash tests are presented to demonstrate the limitations and improvement. First, simulation of a frontal barrier impact with no rotation is expected to be insensitive to pulse duration.

Side impact structural characteristics for a front wheel drive passenger car are investigated to compare occupant compartment stiffness to that for lateral collisions that involve the suspension and A or C pillars. Moving deformable barrier crash tests are analyzed to determine stiffness at a variety of speeds. A truck-to-car crash test in which the passenger car is struck laterally at the left front is analyzed to derive the stiffness of the structure involving the suspension. For the MDB and the truck-to-car crash tests the effects of post-impact vehicle rotation is evaluated. Structural restitution is estimated quantitatively. The off-compartment lateral structural stiffness is determined to be more than twice that for the occupant compartment.

The coefficient of restitution is an indicator of the elasticity of a collision. Restitution, or elastic rebound of a deformed surface, contributes to the change in velocity of collision partners, a common measure of injury severity in automobile collisions. Because of the complex nature of collisions between motor vehicles, the characterization of the expected magnitude of the coefficient in such collisions lacks detail and mechanisms influencing its value are not well understood. Using crash test data from the National Highway Traffic Safety Administration (NHTSA), this study investigates the expected magnitude of the coefficient of restitution and mechanisms influencing restitution in automobile collisions. Both vehicle-to-barrier and vehicle-to-vehicle tests are considered for all types of collisions. The influence of a variety of collision and vehicle parameters on restitution is also explored.