Develop biomechancially-based skull fracture criteria that are applicable to crash environment head impacts.

The current Head Injury Criterion (HIC) is based on head impact tests that are over twenty years old. More data has been collected since that provides a better basis for evaluating mechanisms of skull fracture.

The acceleration response of the fracturing head is in general dramatically different from that of a non-breakable dummy head form undergoing the same impact. Since the dummy heads provide the acceleration data that is used to assess safety, injury measures have to be based on a relationship between measured dummy output and actual injury. There exists an infinite number of possible measures that can relate acceleration time response to fracture injury (maximum acceleration, average acceleration, HIC, etc.). Biomechanically-based quantities measuring fracture (i.e. strain in the skull) are most likely to be biofidelic under all circumstances.

Reconstruct existing skull fracture tests using physical model heads consisting of ideal shapes including the Hybrid III dummy headform to establish the correlation between dummy output and skull fracture. Use finite element models to establish the biomechanical origin of observed fractures. Establish the best acceleration based measure that can be selected, based on its statistical characteristics, its ability to properly interpret crash test data, and it correlation with the underlying biomechanical process. Validate emerging understanding against prospective cadaver impact tests.

A biomechanically based understanding of skull fracture will support modification or upgrade of FMVSS criteria for head injury. It will also facilitate the extension of these findings to other population groups and broader impact conditions

Reproduction of existing cadaver test data using dummy headforms has been completed. Further validation testing using cadaver head drops is on-going for the selected skull fracture criterion.

• Bandak, F.A. "Impact Traumatic Brain Injuries: A Mechanical Perspective", in Proceeding of the 7th Lubeck Neurotramatology Conference. 1997, In print.
• Bandak, F.A., "Biomechanics of Impact Traumatic Brain Injuries", in Crashworthiness of Transportation Systems: Structural Impact and Occupant Protection, J. A. Ambrosio et al (Eds.). Kluwer Academic Publishers, 53-93, 1996
• Bandak, F.A., Eppinger, R.H., and Ommaya, A.K. Traumatic Brain Injury: Bioscience and Mechanics. Mary Ann Libert, New York, 1996.
• Bandak, F.A., Vander Vorst, M.J., and Stuhmiller, J.H., "An Imaging-based Computational and Experimental Study of Head Injury I: Skull Fracture Model", J. Neurotrauma, 12, 4, 679-688, 1995.