Evaluation of the injury potential of automotive impact configurations, vehicle components, or the vehicles themselves is necessarily empirical in nature. Such experimentation requires an anthropomorphic test device that simulates the loading on the vehicle or vehicle component. It is also necessary that a prediction be made of the injury resulting from that loading. In most cases, the extent of the injury is of prime importance in determining the severity of the impact. Component and vehicle redesign can then be performed to mitigate the injury in subsequent tests or in the actual crash environment.

It is generally accepted that the Hybrid III dummy is the most advanced test device in determining thoracic injury. That fact, combined with its other attractive features, makes it a candidate for a standardized test device. Hybrid III thoracic injury evaluation is accomplished by measurement of an average chest deflection which is in turn related to injury based on previous cadaver impact studies. The current Hybrid III thorax can accommodate a maximum deflection of slightly over 76 mm (3 inches). Thus, the Hybrid III is designed to differentiate between the nonserious injuries (AIS 1- 3 ) and to identify the presence of a serious injury (AIS>​3).

This limited injury measurement capability of the Hybrid III has left a void in the ability to evaluate automotive crash environments. Certainly, it is of paramount importance to be able to differentiate between serious and nonserious injuries and qualitatively determine an improvement in the design of a vehicle or vehicle component. However, the inability to quantitatively measure serious injuries is a handicap. Absent this ability, the assumption must be made by the test engineer that all injuries above AIS 3 are equally serious and life threatening. Any assumption short of this is guesswork. It would be advantageous to be able to differentiate between a life threatening AIS 5 Injury and a serious but not critical AIS 4 Injury. This is especially the case in establishing the survivability of severe crash environments as in unrestrained occupant or high speed collisions.

The objective of the present research is to redesign the Hybrid III thorax to accommodate measurement of injury levels greater than AIS 3. A review of the cadaver data is performed to determine which measurable parameter (deflection, acceleration) can be used to best differentiate serious injuries. The Hybrid III thoracic structure is then redesigned to facilitate measurement of this parameter. In addition, two limiting characteristics of the current ribs, those being temperature sensitivity and endurance, will be considered and improved if possible.