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This research examines the effects of impactor characteristics on the calculated structural stiffness parameters A and B for the struck sides of late-model vehicles. This study was made possible by crash testing performed by the National Highway Traffic Safety Administration involving side impacts of the same vehicle line with both a rigid pole and with a moving deformable barrier. Twenty-nine crash test pairs were identified for 2018 model-year vehicles. Of 60 total tests, 49 were analyzed. Test data for 19 vehicles impacted in both modes resulted in A and B values considered to be valid. Classifying these 19 vehicles according to the categories defined by Siddall and Day, only Class 2 multipurpose vehicles were represented by enough vehicles (10) to search for trends within a given vehicle category. For these vehicles, more scatter in the results was observed in both A and B values for the MDB impacts compared to the pole impacts.

Crash tests of vehicles by striking deformable barriers are specified by Government programs such as FMVSS 214, FMVSS 301 and the Side Impact New Car Assessment Program (SINCAP). Such tests result in both crash partners absorbing crush energy and moving after separation. Compared with studying fixed rigid barrier crash tests, the analysis of the energy-absorbing behavior of the vehicle side (or rear) structure is much more involved. Described in this paper is a methodology by which analysts can use such crash tests to determine the side structure stiffness characteristics for the specific struck vehicle. Such vehicle-specific information allows the calculation of the crush energy for the particular side-struck vehicle during an actual collision – a key step in the reconstruction of that crash.

Crash tests of vehicles by striking deformable barriers are specified by Government programs such as FMVSS 214, FMVSS 301 and the Side Impact New Car Assessment Program (SINCAP). Such tests result in both crash partners absorbing crush energy and moving after separation. Compared with studying fixed rigid barrier crash tests, the analysis of the energy-absorbing behavior of the vehicle side (or rear) structure is much more involved. Described in this paper is a methodology by which analysts can use such crash tests to determine the side structure stiffness characteristics for the specific struck vehicle. Such vehicle-specific information allows the calculation of the crush energy for the particular side-struck vehicle during an actual collision – a key step in the reconstruction of that crash.

Objective: A friction rollover test was conducted as part of a rollover sensing project. This study evaluates vehicle and occupant responses in the test. Methods: A flat dolly carried a Saab 9-3 sedan laterally, passenger-side leading to a release point at 42 km/h (26 mph) onto a high-friction surface. The vehicle was equipped with roll, pitch and yaw gyros near the center of gravity. Accelerometers were placed at the vehicle center tunnel, A-pillar near the roof, B-pillar near the sill, suspension sub-frame and wheels. Five off-board and two on-board cameras recorded kinematics. Hybrid III dummies were instrumented for head and chest acceleration and upper neck force and moment. Belt loads were measured. Results: The vehicle release caused the tires and then wheel rims to skid on the high-friction surface. The trip involved roll angular velocities >300 deg/s at 0.5 s and a far-side impact on the driver’s side roof at 0.94 s. The driver was inverted in the far-side, ground impact.

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.

Objective: This study analyzes rear sled tests with a 95th% male and 5th% female Hybrid III dummy in various seating positions on ABTS (All Belt to Seat) seats in severe rear impact tests. Dummy interactions with the deforming seatback and upper body extension around the seat frame are considered. Methods: The 1st series involved an open sled fixture with a Sebring ABTS seat at 30 mph rear delta V. A 95th% Hybrid III dummy was placed in four different seating positions: 1) normal, 2) leaning inboard, 3) leaning forward and inboard, and 4) leaning forward and outboard. The 2nd series used a 5th% female Hybrid III dummy in a Grand Voyager body buck at 25 mph rear delta V. The dummy was leaned forward and inboard on a LeSabre ABTS or Voyager seat. The 3rd series used a 5th% female Hybrid III dummy in an Explorer body buck at 26 mph rear delta V. The dummy was leaned forward and inboard on a Sebring ABTS or Explorer seat.

Crush energy assessment methods rely on the characterization of a vehicle’s structure, through a comparison with crash tests of a similar vehicle. For frontal impacts, the vast majority of these tests involve a flat rigid barrier. When the reconstructionist is presented with a frontal underride/override crash, however, the structural load pattern and the deformation mode suggest that the comparison with flat barrier tests may not be valid. This has been confirmed by prior studies. With few exceptions, for any given vehicle, there are no crash data in an underride/override mode that are useful for analysis purposes. The purpose of this research was to bridge the gap so that flat barrier data, specific to the vehicle in question, could be applied to underride/override cases. This entailed the development of a measurement protocol, a structural model for such crashes, and a procedure for analyzing the load cell data that exist for many barrier crash tests.

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.

The original Malibu II study, conducted by Bahling et al, found that neck compression loading in rollover crashes is caused by the occupant moving toward the ground and therefore, roof crush was not causally related to the loading. Some have disputed this finding claiming that the occupant does not “dive toward the roof,” but rather, the roof “moves in” toward the occupant, and that roof deformation is the primary cause of cervical spine injuries in rollover crashes. The original study included a detailed analysis of film and force transducer data for 10 Potentially Injurious Impacts (PII's). This paper presents an independent analysis of these 10 PII's and one additional PII. This analysis uses the film and transducer data to evaluate the timing of roof deformation and neck loading, the magnitude of roof deformation at the time of peak neck load, and the motion of the vehicle and occupants in the inertial reference system.

In frontal crashes, lateral deformations can occur as a result of various mechanisms. Unfortunately, the crush energy associated with such deformations cannot be assessed as long as the structural properties are unknown. That has been the situation to date, due to the lack of appropriate crash test data. The present research attempts to address this deficit. A passenger car was crash-tested in a mode designed to induce lateral deformations that are significant compared to longitudinal crush. This was done via a series of three repeated impacts on the same vehicle so as to obtain, in a cost-effective manner, structural characterization data at increasing crash severities. Various cause-and-effect relationships (structural characterization models) were considered with an eye to selecting the one that best predicts the crush energy. Insights obtained from analyzing the behavior of the front structure are presented.

Based upon a review of the literature and new test data, the human and vehicle factors leading to head-to-roof contact in rollovers are quantified and illustrated. Vehicle design countermeasures and suggested areas of research are presented. Higher and stronger roofs and improved restraints must be analyzed as a system to evaluate the potential benefits in rollovers.

Thanks to years of research and development by vehicle manufacturers, suppliers, legislation, and the entire safety community, the side airbag has become a critical safety device to reduce injury and save lives. This new collection of technical research highlights the progression of these essential safety features, providing a complete and thorough perspective through the analysis of both early patents and recent side airbag system developments. Advances in Side Airbag Systems begins with an introduction by editor Donald E. Struble, chronicling the progress made since the mid-1980s in offering improved side impact protection to the motoring public. Authored by leading experts in their respective fields, this book features a comprehensive collection of 26 landmark technical papers. Its scope includes not only thorax airbags, but other inflatable devices designed for side impacts and rollovers.

Understanding occupant kinematics is an important part of accident reconstruction, particularly with respect to injury causation. Injuries are generally sustained as the occupant interacts with the vehicle interior surfaces and is rapidly accelerated to the struck component's post-impact velocity. This paper describes some methods for assessing occupant kinematics in a collision, and discusses their limitations. A useful technique is presented which is based on free-body analysis and can be used to establish an occupant's path of motion relative to the vehicle, locate the point of occupant contact, and determine the occupant's velocity relative to that contact location.

Due to the upgrade of FMVSS 214 and the emergence of side NCAP tests, there is a growing body of crash test data on vehicle side structures. Such data would be very useful to reconstructionists, except that the struck vehicle behavior is masked, in part, by the use of a deformable moving barrier in the test. The post-impact dynamics and the energy absorption by the barrier itself must be accounted for if the desired vehicle structural characterization is to be extracted. Attempts prior to this paper to achieve a side structure characterization have dealt with these issues by invoking various simplifying assumptions. Unfortunately, these have not been supported by a foundation in either physics or measurement. Questions have also been raised whether prior characterizations of the barrier face are appropriate, in view of the prior crash modes being so unlike the FMVSS 214 test. To address these issues, crash tests of the barrier itself, in an appropriate crash mode, have been conducted.

A key aspect of accident reconstruction is the calculation of how much kinetic energy is dissipated as crush. By far the most widely used methods are derivatives of Campbell’s work, in which a linear relationship between residual crush and closing speed is shown to imply an underlying linearity between force and crush. “Consant-stiffness model” is the term used for such a representation of structural behavior. Difficulties arise, however, when significant non-uniformities are present in the crush pattern (as in narrow-object and/or side impacts, for example). The term “residual crush” becomes more ambiguous. Do we mean maximum crush, area-weighted average crush, or some other measure of residual deformation? And is it sufficient to represent the non-uniform crush pattern by a single parameter? Such considerations led to a re-development of the fundamental structural models, with an eye to determining whether the classical constant-stiffness model is the most appropriate.

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.

Since air bags emerged as an occupant protection concept in the early '70s, their development into a widely-available product has been lengthy, arduous, and the subject of an intense national debate. That debate is well documented and will not be repeated here. Rather, operating principles and design considerations are discussed, using systems and components from the developmental history of airbags as examples. Design alternatives, crash test requirements, and performance limits are discussed. Sources of restraint system forces, and their connection with occupant size and position, are identified. Various types of inflators, and some of the considerations involved in “smart” systems, are presented. Sensor designs, and issues that influence the architecture of the sensor system, are discussed.

Occupant simulation models have been used to study trends or specific design changes in “typical” accident modes such as frontal, side, rear, and rollover. This paper explores the usage of the Articulated Total Body Program (ATB) as an accident reconstruction tool. The importance of model validation is discussed. Specific areas of concern such as the contact model, force-deflection data, occupant parameters, restraint system models, head/neck loadings, padding, and intrusion are discussed in the context of accident reconstruction.

Rollover accidents are responsible for a significant percentage of crash injuries. Increasing seat belt restraint use is the most effective way to reduce rollover injuries. Injuries to restrained occupants are also of interest. It has been suggested that head/neck injuries are caused by roof crush, and that modification to roof structures and seat belt systems would lead to a substantial reduction in severe rollover injuries. Field accident data and rollover testing are used to evaluate the relationship between roof crush, seat belt design, and severe rollover injuries.