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Mild traumatic brain injury associated with blast exposure is an important issue, and cavitation of the cerebrospinal fluid (CSF) has been suggested as a potential injury mechanism; however, physical measurements are required to evaluate cavitation thresholds. Modifications to a Split Hopkinson Pressure Bar (SHPB) apparatus were investigated with the aim to generate localized fluid cavitation and measure the cavitation threshold of fluids. The proposed design incorporated a novel closed cavitation chamber to generate localized cavitation resulting from a reflected compression pulse, which was generated by a spherical steel striker and Polymethyl methacrylate (PMMA) incident bar. A numerical model of the incident bar was developed and validated with 24 independent tests (cross-correlation: 0.970-0.997), and this was extended to a numerical model of the apparatus including the chamber, validated with 27 independent tests (cross-correlation: 0.921) to predict the tensile fluid pressure in the chamber. Tests on distilled water were performed with comparable numerical results for the chamber strain (R 2 : 0.875) and chamber end-wall velocity (R 2 : 0.992). The pressure in the chamber was determined from the model to avoid introducing a nucleation site via a pressure gauge, and was verified with a firstorder approximation showing good agreement (R 2 : 0.892). The 50% probability of cavitation for distilled water was −3.32 MPa ±3%, comparable to values in the literature. This novel apparatus, including a closed confinement chamber integrated with a polymeric SHPB apparatus was able to create localized fluid cavitation with loading comparable to blast exposure. Future studies will include the measurement of CSF cavitation pressure.

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.