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Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder-belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder-belted occupant in a high retention seat with ≻1,700 Nm moment or ≻5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or override by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt.

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.

In this study, U.S. crash data was analyzed to better understand bounce-over rollovers. Crash data was reviewed to evaluate the distribution of bounce-over crashes and injuries, initiation objects and impact locations. In passenger cars, bounce-over crashes account for 8.4% of rollovers but involve 36.2% of the seriously injured belted drivers. Most bounce-overs are initiated by contact with narrow objects such as a pole, tree or barrier, or large objects such as a ditch or embankment. Contact often occurs in the front of the vehicle. After contact, the vehicle yaws and rolls, and serious injuries are often sustained to the head. Based on field data, a laboratory test was developed to simulate a narrow object bounce-over. The test consists of towing a vehicle laterally on a fixture towards a stationary, angled barrier resting in gravel. The moving fixture is decelerated and the vehicle is released. The vehicle front impacts the edge of the barrier, simulating a narrow object impact.

During the past decade, there has been a steady increase in studies addressing rollover crashes and injuries. Though rollovers are not the most frequent crash type, they are significant with respect to serious injury and interest in rollovers has grown with the introduction of SUVs, vans, and light trucks. A review of Occupant and Vehicle Responses in Rollovers examines relevant conditions for field roll overs, vehicle responses, and occupant kinetics in the vehicle. This book edited by Dr. David C. Viano and Dr. Chantal S. Parenteau includes 62 technical documents covering 15 years of rollover crash safety, including field crash statistics, pre- and rollover dynamics, test procedures and dummy responses.

A new generation of seats has been designed to specifications for high retention (HR) in a Quasistatic Seat Test (QST). The QST involves occupant loading of the seat in a rearward direction and targets peak H-point moment to >1700 Nm giving an energy transfer capability of 2000 J. QST tests from 1998-2000 were compared to results from pre-HR seat designs of the late 1980s and early 1990s to determine performance improvements. Twenty-seven QST tests of HR seats were randomly selected from a larger series and were evaluated for strength and seat deformation under occupant loading. They represented 20 different seat types from four suppliers. Averages and standard deviations in QST results were computed. In addition, eight repeat tests were conducted with one seat to determine repeatability of the QST. These data were compared to an earlier repeatability study of the 1994 W pre-HR seat, which was evaluated at two facilities.

This paper reviews issues relating to seats including design for comfort and restraint, mechanics of discomfort and irritability, older occupants, and low-back pain. It focuses on the interface between seating technology and occupant comfort, and involves a technical review of medical-engineering information. The dramatic increase in the number of features currently available on seats outreaches the technical understanding of occupant accommodation and ride comfort. Thus, the current understanding of seat design parameters may not adequately encompass occupant needs. The review has found many pathways between seating features and riding comfort, each of which requires more specific information on the biomechanics of discomfort by pressure distribution, body support, ride vibration, material breathability, and other factors. These inputs stimulate mechanisms of discomfort that need to be quantified in terms of mechanical requirements for seat design and function.

This paper covers the development of the General Motors Energy Absorbing Steering System beginning with the work of the early crash injury pioneers Hugh DeHaven and Colonel John P. Stapp through developments and introduction of the General Motors energy absorbing steering system in 1966. evaluations of crash performance of the system, and further improvement in protective function of the steering assembly. The contributions of GM Research Laboratories are highlighted, including its safety research program. Safety Car, Invertube, the biomechanic projects at Wayne State University, and the thoracic and abdominal tolerance studies that lead to the development of the Viscous Injury Criterion and self-aligning steering wheel.

This paper contains a review of current information on biological structure, material properties and failure characteristics of bone, articular cartilage, ligament and tendon. The load-deformation response of biological tissues is presented with particular reference to the microstructure of the material. Although many of the tissues have been characterized as linear, elastic and isotropic materials, they actually have a more complicated response to load, which includes stiffening with increasing strain, inelastic yield, and strain rate sensitivity. Failure of compact and cancellous bone depends on the rate, type, and direction of loading. Soft biological tissues are vlscoelastie and exhibit a higher load tolerance with an increasing rate of loading. The paper includes a discussion on the basic principles of biomechanics and emphasizes material properties and failure characteristics of biological tissues subjected to impact loading.

Life threatening chest injury can involve partial or full tears of the aorta. Investigations of fatal injuries in automobile accidents indicate that aortic trauma occurs in 10-20% of the cases. The major sites of aortic trauma include the aortic isthmus, the root, and the aortic insertion at the diaphragm - all of which are points of aortic tethering. The biomechanics of the injury process involve stretching of the vessel from points of tethering and hydrodynamic increases in blood pressure, which stretch the tissue to failure at a strain of about 150%. The non-isotropic stretch response of aortic tissue is discussed with reference to the frequent transverse orientation of the laceration. Congenital and pathophysiological conditions also influence the failure characteristics of the tissue. The significant factors associated with traumatic injury of the aorta are discussed in this review paper which is based on published technical information.

The study was directed toward improving our understanding how postcrash column compression and steering wheel deformation relate to the driver interaction with an energy absorbing steering system during automotive collisions. Frontal sled tests conducted at 19–37 km/h investigated the Part 572 antropomorphic dummy interaction with a ball-sleeve column steering assembly over a range of column angles and surrogate postures. Neither column compression nor steering wheel deformation correlated with the mechanical severity of the test surrogate interaction with the steering system. The steering wheel deformed before the column compressed and the degree of wheel deformation strongly depended on the surrogate load distribution, the steering wheel being an important energy absorbing element.

Five anesthetized porcine subjects were exposed to blunt thoracic impact using a 21 kg mass with a flat contact surface traveling at 3.0 to 12.2 m/s. The experiments were conducted to assess the appropriateness of studying in vivo mechanical and physiological response to thoracic impact in a porcine animal model. A comprehensive review of comparative anatomy between the pig and man indicates that the cardiovascular, respiratory and thoracic skeletal systems of the pig are anatomically and functionally a good parallel of similar structures in man. Thoracic anthropometry measurements document that the chest of a 50 to 60 kg pig is similar to the 50th percentile adult male human, but is narrower and deeper. Peak applied force and chest deflection are in good agreement between the animal's responses and similar impact severity data on fresh cadavers.