A mechanical model for spherical fragments penetrating gelatine

The behaviour and effects of a spherical fragment penetrating a simulant and those of biological tissue are similar. To accurately describe the interaction between spherical fragments and muscle tissue, this study first discusses the wounding mechanism and establishes a mechanical model considering the effects of strain rate based on the properties of gelatine, which is a widely used representative simulant in physical surrogates for muscle tissue. Subsequently, experiments wherein gelatine was penetrated by spherical fragments with diameters of 3, 4, and 4.8 mm were conducted. The inertial and viscous resistance coefficients were identified using the least squares method and the experimental results obtained for the 4-mm spherical fragment. Numerical calculations show that the mechanical model agrees well with the experimental values. Further, the mechanical model's ability to adequately describe the motion of spherical fragments penetrating gelatine with good generality is proved. The proposed model can therefore provide a scientific basis for small arms ammunition design and protection evaluation.