The axisymmetric response of a fluid-filled spherical shell to a local radial impulse--a model for head injury.

This investigation is concerned with determination of the dynamic response of a fluid-filled spherical shell subjected to a local radial impulsive load. From the application point of view, such a fluid-shell system is considered to be a simple, but to date, the most improved theoretical model representing the human head when subjected to impulsive external loads. Analysis is based on linear shell theory which includes both membrane and bending effects. The motion of the fluid is assumed to be governed by the wave equation. Laplace transform technique is used in obtaining the transient axisymmetric response of the system to a local radial impulsive load. The solutions thus obtained for the velocity potential of the fluid and the displacement components of the shell mid-surface are the Green's functions of the problem with respect to time. Some numerical results for the theoretical model are obtained for a set of appropriate data. The comparison is made for the stress distributions at various times in the shell for both the empty and the fluid-filled cases. In the fluid-filled case the excess pressure propagation in the fluid is also discussed. The possible locations of brain damage and skull injury are indicated on the basis of the numerical computations.