Population Variations in Helmet Fit Affect Calculated Head Injury Risk in Blunt Impact

A helmet will not fit the same way on different individuals with different head sizes and shapes. However, the degree to which subject-specific fit differences may affect the risk of injury remains understudied. In this study, we used experimentally measured head/helmet contact force to generate different levels of initial padding compression when applied to a finite element head model. The deformed padding configuration was used as the initial condition for subsequent impact analyses. As the level of initial padding compression increased, the resulting maximum force, total impulse, and the resulting head injury metrics increased by up to 20%. The results of this study highlight the importance of accurate modeling of initial pad deformation prior to impact and provide a workflow for establishing such a configuration in other helmet applications.