Development of a finite element model specific to the female thorax for non-penetrating ballistic impact

Finite element modeling in biomechanics has been widely used for several decades to investigate the injury mechanisms and tolerance limits of various biological structures. The development of biomechanical models includes choosing an anthropometry, which generally leads to a 50th percentile male model. In that context, derived numerical injury metrics are dedicated to males, although conclusions of these studies are generalized to the whole population including female subjects. This study proposes to address the existing paucity concerning female blunt thoracic injuries and add to the understanding of thoracic injuries at a numerical level. Thus, a female finite element model of the thorax has been developed, named HUBxx, in the same way as the existing male geometry model is named HUByx. A 3-D reconstruction of the geometry of the various components of the model was based on literature data. Constitutive laws were implemented in the model for soft tissues and skeletal structures, and a numerical replication of existing experimental tests was carried out in the context of blunt ballistic impacts. The results show that the numerical responses of the HUBxx model are in good agreement with the female experimental corridors for both sternal and breast impacts, demonstrating its biofidelity and its ability to reproduce the mechanical response of the female thorax. In contrast, a male finite element model (SurHUByx FEM) scaled-down to female external anthropometric dimensions fails to reproduce the characteristics of the female experimental corridors. This study provides tools and data for specific investigations of female thoracic injuries, given the differences observed between males and females.