Application of a fluid-filled spherical sandwich shell as a biodynamic head injury model for primates.

In this paper, two areas are investigated: first, the effect of pulse duration on skull fracture and brain injury and, second, under what conditions a scaling can be considered between subhuman primates and human. The skull is modeled as a spherical sandwich shell representing the general structure of the skull bones as being the compact inner and outer tables separated by a porous diploë layer. The brain and surrounding cerebrospinal fluid are modeled as an acoustic fluid with properties similar to those of water. The fluid-shell system is subjected to a local axisymmetric and arbitrary time-dependent external pulse and the transient response of the system is determined by numerical methods. The effect of pulse duration is investigated by choosing the pulse as the Heaviside function. Pulses with short duration are found to be less damaging as far as skull fracture and brain injury are concerned. Human head impact tolerance curves are obtained. For the second part of the investigation, a more realistic pulse containing both exponential and sine components is chosen to study the responses of the models of the human head and four species of primates. The numerical results are obtained for the same magnitude of the pulse as well as for equal magnitudes of initial acceleration after impact.