Minimization of Analytical Injury Metrics for Head Impact Injuries D Sanchez-Molina, J. Velazquez-Ameijide, C. Arregui-Dalmases, J. R. Crandall, and C. Untaroiu January, 2012 Abstract Objective: Compare the predictions of the Head Injury Criterion (HIC), currently used to predict the risk of traumatic brain injury in frontal ve- hicle impact and pedestrian impact tests, with the predictions of other empirical and analytical injury metrics. Methods: The appropriateness of different criteria relative to injury met- rics derived from a head finite element model is investigated for different deceleration pulses in this research. Empirical injury metrics are com- puted by direct calculation for different analyzed pulses. In addition, for each pulse full FEM simulations of a complete human head have been performed by means of SIMon Model. The computations are used for calculating the analytical injury metrics. Results: This paper shows that an optimal head deceleration curve based on HIC does not minimize other analytical injury metrics. The results obtained in this study suggest that the HIC criterion does not necessarily provide the same severity ranking for different external loadings to the head as the injury metrics derived from the finite element models. Conclusion: Consequently, countermeasures designed based only on HIC could differ significantly from those based on analytical injury measures computed by FE models. The use of multiple injury metrics is recom- mended given that no scalar measure seems to be positively and strongly correlated with relevant injury metrics. 1 Introduction Recent data show that approximately 1.6 million people suffer a Traumatic Brain Injury (TBI) each year in the United States, 51,000 of them die; 290,000 are hospitalized and 1.2 million are treated and released from an emergency department ([10, 17]). Worldwide, the significance of TBI as a leading cause of mortality and long-term morbidity is also well established ([6]). Deformation of soft brain tissues within the skull can produce severe TBI. While the precise injury metrics for TBI remain an open research issue, studies have shown that TBI can be correlated with regions of internal strain in the 1