ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

the coup. The results of the investigation involving the model with improved skull and
brain geometry (Stage 2) are similar, including an equal location of the critical value for
the prediction of the nature of the response. These results agree well with the
observations of Young and Morfey [3], indicating that under certain impact conditions
the pressure response in the brain will be dynamic, and this occurs despite the
significant changes to the models used: a large increase in mesh density, non-spherical
(i.e. realistic skull) geometry, and direct modeling of the impact (not an assumed
pressure-time history). It is believed that this research will have important implications
for injury preventative design, diagnosis, treatment and forensic investigation of blunt
head injuries. For example, it is necessary to have a simple mathematical expression for
the prediction of head injury severity which may inform decisions regarding immediate
and long-term treatments. The head injury criterion (HIC) is a widely used predictor of
blunt head injury severity, but based solely on the resultant linear acceleration of the
head. The accuracy of the HIC has come under much debate, and despite its once
widespread use it is now regarded in the literature as a poor predictor of severity. One of
the reasons this is the case may be that the HIC does not take into account impact
duration, which the results of this research indicate is a critical parameter in predicting
the magnitude and nature of the pressures in the brain.
The large pressure transients observed at the coup and contrecoup in this study suggest
that dynamic pressure magnification may be the cause of the well documented
“contrecoup effect”: a hereto poorly understood phenomenon in which trauma of the
brain is observed not only directly beneath the point of a blunt impact, but also
diametrically opposite.
A manuscript detailing the results and implications of the Stage 3 investigation is
currently being prepared for publication in a peer-reviewed journal.
8. REFERENCES
[1] US Centre for Disease Control and Prevention, 2010, Get the stats on traumatic
brain injury in the United States.
[2] Hardy W., Khalil T. B., and King A. I., 1994, “Literature review of head injury
biomechanics,” International Journal of Impact Engineering, pp. 561-586.
[3] Young P. G., and Morfey C. L., 1998, “Intracranial pressure transients caused by
head impacts,” International Research Council on the Biomechanics of Impact
(IRCOBI) Conference Proceedings, Goteborg, Sweden, pp. 391-403.
[4] Jiang H., Young P. G., and Dickinson S., 1996, “Natural frequencies of vibration
of layered hollow spheres using exact three-dimensional elasticity equations,”
Journal of Sound and Vibration, 195(1), pp. 155–162.
[5] Young P. G., 2003, “An analytical model to predict the response of fluid-filled
shells to impact—a model for blunt head impacts,” Journal of Sound and
Vibration, 267(5), pp. 1107-1126.
[6] Engin A. E., 1969, “The axisymmetric response of a fluid-filled spherical shell to
a local radial impulse–A model for head injury,” Journal of Biomechanics, 2(3),
pp. 325–341.
[7] Gadd C. W., Nahum A. M., Schneider D. C., and Madeira R. G., 1970,
“Tolerance and properties of superficial soft tissues in situ,” Proceedings of the
14th STAPP Car Crash Conference, pp. 356-368.
[8] Nahum A. M., Smith R., and Ward C. C., 1977, Intracranial pressure dynamics
during head impact, New Orleans, LA, USA.