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Numerous Accidents with air bag equipped cars have been investigated resulting in a question whether the air bag had deployed or not. This question was based on the pictures of the damaged cars and results of accident reconstruction. In the past, sometimes the change of velocity of the car in a crash was directly determined on the basis of damage of the car. The damage and the velocity of the vehicle during accident do not necessarily correlate with regard to air bag deployment. The quality of accident analysis and reconstruction has a significant affect on the interpretation of accident event and it’s consequences. The decision whether the air bag should deploy or not in the real world accident can not be understood without in-depth knowledge of significant physical parameters monitored by the control unit. The key issues relating to the air bag deployment decision in an accident and the design of air bag control unit are described.

Up to now, incompatibility of cars was mainly derived from theoretical considerations due to differences with regard to mass, stiffness, and geometry. Numerous accident analyses and reports only showed, that mass is a dominant factor for the injury outcome in car-to-car collisions. The same analyses have difficulties to assess the influence of stiffness and geometry. One reason is the wide scattering of the injury outcome due to other more important variables than incompatibility. A second reason is the fact that stiffness correlates more or less with the mass. A third reason is the effect of the non-linearity of the geometry influence that means a positive influence of incompatible weak structures causes a reduced acceleration, but with an increased risk of intrusion into the passenger compartment. This can be observed at high impact speeds and/or low overlap degrees. These effects can be seen from accident analysis.

The purpose of this research was to present and analyze a previously unreported mechanism of injury within the automotive crash environment - spinal burst or compression fractures due to a vertical force component. Spinal burst fractures are comminuted fractures of the vertebral body which are often associated with retropulsed bone fragments into the spinal. Compression fractures are less traumatic fractures of the vertebral body with minimal comminution. Both fracture types can have varying degrees of neurologic deficit. The mechanism of injury is hypothesized to be a high energy compressive load along the axis of the spine initiated through the buttocks and pelvis or through torso augmentation (inertial loading of the lumbar spine by the torso). Four crashes are presented as evidence of this injury mechanism within the automotive crash environment: two in the United States and two in Germany.

The risk of head or chest injuries is usually evaluated by means of acceleration measurements using a dummy. Unfortunately, this data provides no information on load distribution over the contact areas which is often related to localized fractures of the bony structure. Therefore, new methods of measuring local forces were developed. 1. Pressure indicating devices attached to a dummy's face are capable of monitoring the local pressure during impact; foil's color change is interpreted by means of digital image analysis. 2. A velocity sensitive viscous tolerance criterion was calculated from the chest compression response of a dummy instrumented with strain gauges on the ribs. The application of advanced techniques in laboratory tests clearly supports the experience of improved protection potential through the use of airbag systems.

The damage pattern of about 30% of accident vehicles with injured occupants corresponds to that created in offset head-on collisions. An accident reconstruction method using the vehicles' deformation energies as operands is introduced for this collision type. The parameters so determined are compared for accidents both with and without glance-off, and their effect on the different injury mechanisms of the belted driver is discussed. A theory is suggested regarding the cause of serious injuries to the lower extremities in glance-off accidents, and is supported by examples. To confirm the results crash tests involving glance-off are carried out.