Assessment of Thorax Finite Element Model Response for Behind Armor Blunt Trauma Impact Loading Using an Epidemiological Database

Abstract

Non-perforating ballistic impacts on thoracic armor can cause blunt injuries, known as behind-armor blunt trauma (BABT). To evaluate the potential for this injury, the back face deformation (BFD) imprinted into a clay backing is measured; however, the link between BFD and potential for injury is uncertain. Computational human body models (HBM) have the potential to provide an improved understanding of BABT injury risk to inform armor design but require assessment with relevant loading scenarios. In the present study, a methodology was developed to apply BABT loading to a computational thorax model, enhanced with refined finite element mesh and high-deformation rate mechanical properties. The model was assessed using an epidemiological BABT survivor database. BABT impact boundary conditions for 10 cases from the database were re-created using experimentally measured deformation for specific armor/projectile combinations, and applied to the thorax model using a novel prescribed displacement methodology. The computational thorax model demonstrated numerical stability under BABT impact conditions. The predicted number of rib fractures, the magnitude of pulmonary contusion, and injury rank, increased with armor BFD, back face velocity, and input energy to the thorax. In 3 of the 10 cases, the model overpredicted the number of rib fractures, attributed to impact location positional sensitivity and limited details from the database. The integration of an HBM with the BABT loading method predicted rib fractures and injury ranks that were in good agreement with available medical records, providing a potential tool for future armor evaluation and injury assessment.

Evaluation and prediction of material fatigue characteristics under impact loads: review and prospects

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A new biomechanical FE model for blunt thoracic impact

“…Once created, surrogates (either numerical or physical ones) were compared with experimental data to ensure their biofidelity. Some numerical models such as HUByx (Roth et al, 2013;Bracq et al, 2019a), SHTIM (Nsiampa, 2011), or WALT (Cronin et al, 2021) are consistent with biomechanical corridors and/or different field impact cases. To the authors' knowledge, only a few physical surrogates in the open literature were consistent with ballistic biomechanical corridors, such as BTTR (Bolduc and Anctil, 2010).…”

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