Experimental Studies of Side Impact to the Human Head

This study continues previous experimental studies which review the characteristics of the side impact exposure to the human head. We conducted a series of two experiments. The first series included four sequential impacts which were performed on a single embalmed specimen. This series of impacts showed a good correspondence between peak head acceleration and HIC and confirmed the adequacy of instrument placement and data analysis. The second series studied five impacts performed on individual unembalmed cadavers. The results suggest that side impacts produced pressure gradients in the brain. These superimposed gradients were proportional to the magnitudes of the head acceleration components. The largest component was found to be in the direction of impact and produced positive pressures near the impact and negative pressures opposite the impact. We found that a pressure limiting mechanism acted on the contra-coup side of the brain. Subarachnoid hemorrhages occurred on the high stress and strain brain surfaces. Approximate values for the pressures were determined in computer simulations. Changes in the model and instrumentation are needed in order to improve the accuracy of the computed pressures, changes in the model and instrumentation. The acceleration traces contained vibration or noise which made calculation of rotation acceleration and velocity impossible. The model needs a better representation for the midsaggital sinus.