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Conceptually, a steering wheel mounted air cushion is inflated before the upper torso of the driver significantly interacts with the cushion. However, this might not be the case for some seating postures or vehicle crash environments which could cause the driver to significantly interact with an inflating cushion. These experiments utilized several environments to study the interaction between an inflating driver air cushion and mechanical surrogates. In these laboratory environments, the measured responses of mechanical surrogates increased with diminishing distance between the surrogate's sternum and the steering wheel mounted air cushion.

This study is an extension of previous work on driver air bag deployment loads which used the mid-size male Hybrid Ill dummy. Both small female and mid-size male Hybrid Ill dummies were tested with a range of near-positions relative to the air bag module. These alignments ranged from the head centered on the module to the chest centered on the module and with various separations and lateral shifts from the module. For both sized dummies the severity of the loading from the air bag depended on alignment and separation of the dummy with respect to the air bag module. No single alignment provided high responses for all body regions, indicating that one test at a typical alignment cannot simultaneously determine the potential for injury risk for the head, neck, and torso. Based on comparisons with their respective injury assessment reference values, the risk of chest injury appeared similar for both sized dummies.

Real world crash injury is distributed somewhat uniformly across a wide range of car crash severities. Our current safety evaluation practices address primarily the high severity crashes which have “high” risk of injury hut “low” exposure frequency. Little or no evaluation is directed toward moderate severity crashes which have “low” risk of injury but “high” exposure frequency and result in much of the total occupant injury. Occupant protection evaluation which relies on analysis of laboratory tests using both an injury probability interpretation of test responses and consideration of exposure frequency produces a perceived injury distribution over a broad range of crash severities that appears similar to that for occupants injured in car crashes. In contrast, analysis of laboratory tests using an average tolerance interpretation of test responses results in a perceived injury distribution in which injury only occurs in “high15 severity exposures.

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.

A relationship between the risk of significant thoracic injury (AIS ≥ 3) and Hybrid III dummy sternal deflection for shoulder belt loading is developed. This relationship is based on an analysis of the Association Peugeot-Renault accident data of 386 occupants who were restrained by three-point belt systems that used a shoulder belt with a force-limiting element. For 342 of these occupants, the magnitude of the shoulder belt force could be estimated with various degrees of certainty from the amount of force-limiting band ripping. Hyge sled tests were conducted with a Hybrid III dummy to reproduce the various degrees of band tearing. The resulting Hybrid III sternal deflections were correlated to the frequencies of AIS ≥ 3 thoracic injury observed for similar band tearing in the field accident data. This analysis indicates that for shoulder belt loading a Hybrid III sternal deflection of 50 mm corresponds to a 40 to 50% risk of an AIS ≥ 3 thoracic injury.

Studies conducted in the 1970's suggested that inflatable belt restraints might provide a high level of occupant protection based on experiments with dummies, cadavers and volunteers. Although inflating the belt was one factor which contributed to achieving these experimental results, much of the reported performance was associated with other features in the restraint system. Exploratory experiments with the Hybrid III dummy indicated similar trends to previous studies, belt inflation reducing dummy response amplitudes by pretensioning and energy absorption while reducing displacement. The potential advantage of an increased loaded area by an inflatable belt could not be objectively demonstrated from previous studies or from dummy responses. Clearly, belt inflation can be one component of a belt restraint system which tends to reduce test response amplitudes. However, other belt system configurations have demonstrated similar test response amplitudes.

Injury and disability associated with head (brain), neck (spinal cord) and facial injury account for 61.7% of the total societal Harm in the most recent estimate of motor-vehicle related crash injuries. This paper discusses the need for accurate information on translational and rotational acceleration of the head as the first step in critiquing the Head Injury Criterion (HIC) and other injury predictive methods, and developing a fuller understanding of brain and spinal cord injury mechanisms. A measurement system has been developed using linear accelerometers to accurately determine the 3D translational and rotational acceleration of the Hybrid III dummy head. Our concept has been to use the conventional triaxial accelerometer in the dummy's head to assess translational acceleration, and three rows of in-line linear accelerometers and a least squares analysis to compute statistical best-fits for the rotational acceleration about three orthogonal axes.

The introduction of energy absorbing steering systems has provided a substantial reduction of occupant injury in car crashes. However, the steering system remains the most important source of occupant injury. Injury associated with steering assembly contact is due to high exposure; energy absorbing steering systems reduce the risk of injury for drivers when compared to the injury risk of right front passengers. Our investigation addressed loading of the upper abdominal region by the steering wheel rim using a physiological model for study of soft tissue injury. Injury to the liver was related to the abdominal compression response associated with rim loading. Although liver injury correlated somewhat with peak abdominal compression, a better correlation was found when the rate of compression was also considered. Force limiting by the steering wheel, not by column compression, most strongly influenced the outcome of abdominal injury.

Sled tests were conducted to investigate the dynamics of a Part 572 dummy as a sfunction of the belt restraint configuration and impact direction. The tests involved a 35 km/h velocity change and 10 g deceleration. An “opened” fixture, free of intervening surfaces, was oriented from frontal (0°), through oblique (±30°,±45°, ±60°), to full lateral (±90°). Restraint by only a lap belt resulted in the dummy's upper body rotating about the lap belt and continuing in the direction of sled deceleration. Restraint by a lap-shoulder belt greatly reduced upper-body displacement. However, the displacement and body loading were strongly dependent on the direction of deceleration, i.e., the orientation of the belt relative to the impact direction. When the belted shoulder was opposite the impact (0° to +90°), the belt retained the upper body for impact angles of 0° to 45°.

Far-side lateral impacts were simulated using a Part 572 dummy and human cadavers to compare responses for several belt restraint configurations. Sled tests were conducted having a velocity change of 35 km/hr at a 10 g deceleration level. It was estimated from field data that a 35 km/hr velocity change of the laterally struck vehicle represents about an 80th percentile level for injury-producing lateral collisions. Subjects restrained by a three-point belt system with an outboard anchored diagonal shoulder belt (i.e., positioned over the shoulder opposite the side of impact) rotated out of the shoulder belt and onto the seat. The subject received some lateral restraint due to interaction with the shoulder belt and seatback. The subjects restrained by a three-point belt system with an inboard anchored diagonal shoulder belt (i.e., positioned over the shoulder on the side of impact) remained essentially upright due to shoulder belt interaction with the neck and/or head.

Measurement of chest compression is vital to properly assessing injury risk for restraint systems. It directly relates chest loading to the risk of serious or fatal compression injury for the vital organs protected by the rib cage. Other measures of loading such as spinal acceleration or total restraint load do not separate how much of the force is applied to the rib cage, shoulders, or lumbar and cervical spines. Hybrid III chest compression is biofidelic for blunt impact of the sternum, but is “stiff” for belt loading. In this study, an analysis was conducted of two published crash reconstruction studies involving belted occupants. This provides a basis for comparing occupant injury risks with Hybrid III chest compression in similar exposures. Results from both data sources were similar and indicate that belt loading resulting in 40 mm Hybrid III chest compression represents a 20-25% risk of an AIS≥3 thoracic injury.