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Physical models of the skull-brain system have been subjected to controlled inertial loading experiments in which the deformation response of the surrogate brain was measured. The propose of this report is to present the results of these studies. Two types of models are examined herein; an idealized right circular cylinderical geometry and a baboon skull, sectioned in a midcoronal plane. The surrogate brain, consisting of an optically transparent silicone-gel, contains a painted grid of orthogonal lines with approximately 5mm spacing. The experimental data are presented in the form of nodal displacements and associated strains with one millisecond temporal resolution. The loading conditions are described by the rigid body accelerations of the skull or cylinder models. In each case the motion of the model is a noncentroidal rotation. The experimental results permit one to investigate the relations between the deformation and the acceleration magnitude and temporal characteristics.

This report discusses the development of brain injury tolerance criteria based on the study of three model systems: the primate, inanimate physical surrogates, and isolated tissue elements. Although we are equally concerned with the neural and neurovascular tissue components of the brain, the report will focus on the former and, in particular, the axonal elements. Under conditions of distributed, impulsive, angularacceleration loading, the primate model exhibits a pathophysiological response ranging from mild cerebral concussion to massive, diffuse white matter damage with prolonged coma. When physical models are subjected to identical loading conditions it becomes possible to map the displacements and calculate the associated strains and stresses within the field simulating the brain. Correlating these experimental models leads to predictive levels of tissue element deformation that may be considered as a threshold for specific mechanisms of injury.

This study was conducted to quantify intracranial biomechanical responses and external blast overpressures using physical head model to understand the biomechanics of blast traumatic brain injury and to provide experimental data for computer simulation of blast-induced brain trauma. Ellipsoidal-shaped physical head models, made from 3-mm polycarbonate shell filled with Sylgard 527 silicon gel, were used. Six blast tests were conducted in frontal, side, and 45° oblique orientations. External blast overpressures and internal pressures were quantified with ballistic pressure sensors. Blast overpressures, ranging from 129.5 kPa to 769.3 kPa, were generated using a rigid cannon and 1.3 to 3.0 grams of pentaerythritol tetranitrate (PETN) plastic sheet explosive (explosive yield of 13.24 kJ and TNT equivalent mass of 2.87 grams for 3 grams of material).