The development and safety certification of less lethal projectiles require an understanding of the influence of projectile parameters on projectile-chest interaction and on the resulting terminal effect. Several energy-based criteria have been developed for chest injury assessment. Many studies consider kinetic energy (KE) or energy density as the only projectile parameter influencing terminal effect. In a common KE range (100-160 J), analysis of the firing tests of two 40 mm projectiles of different masses on animal surrogates has been made in order to investigate the severity of the injuries in the thoracic region. Experimental results have shown that KE and calibre are not sufficient to discriminate between the two projectiles as regards their injury potential. Parameters, such as momentum, shape and impedance, influence the projectile-chest interaction and terminal effect. A simplified finite element model of projectile-structure interaction confirms the experimental tendencies. Within the range of ballistic parameters used, it has been demonstrated that maximum thoracic deflection is a useful parameter to predict the skeletal level of injury, and it largely depends on the projectile pre-impact momentum. However, numerical simulations show that these results are merely valid for the experimental conditions used and cannot be generalised. Nevertheless, the transmitted impulse seems to be a more general factor governing the thorax deflection.

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Constitutive equationsThe XF explosive family from NEXTER Munitions relies on a melt cast formulation with a TNT matrix. Melt cast formulations provide a high‐volume ratio of energetic filler material to matrix. This might affect the mechanical response of the material and its damage process. Therefore, a laboratory study has been launched to improve the knowledge of the mechanical behavior of this family of energetic materials. To mimic the conditions observed by the material inside ammunition, we chose to adapt a passive confinement method to the pyrotechnic conditions of the XF‐11585. This relies on an elastic‐perfectly plastic ring that gives us access to the shear behavior for different loadings in quasi‐static regime. This setup allowed us to investigate the physical phenomena involved under both pressure and shear. Then, based on the results obtained, we built an isotropic elastic damage model. This macroscopic modeling of damage is meant to be simple but complex enough to provide an assessment of the material degradation.

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