Comparative Study on Dynamic Mechanical Property Tests and Constitutive Models of W/Pb/Fe-Paraffin Composite Medium Projectile

In response to the need for efficient breaching of door locks with minimal collateral damage to surrounding personnel and facilities in scenarios such as counter-terrorism operations and SWAT assaults, this study addresses the technical challenge of inadequate collateral damage control inherent in traditional rigid projectiles. We developed a low-collateral-damage door lock-breaching munition based on a metal powder composite medium and systematically investigated its performance through experiments, simulations, and theoretical analyses. Using W/Pb/Fe metal powders and paraffin as core materials, we designed and fabricated a baseline specimen (Specimen I), as well as two reinforced specimens: "carbon fiber external encapsulation" (Specimen II) and "3D-printed skeleton embedded+carbon fiber external encapsulation" (Specimen III). Their performance was studied using experiments, theoretical analyses, and numerical simulations. Results of uniaxial compression tests show that the peak strengths of Specimen III (22.72 MPa) and Specimen II (15.47 MPa) are 4.76 and 3.24 times that of Specimen I (4.77 MPa), respectively, with all three exhibiting a four-stage failure mode: "initial blunt compression-microcrack yield-slip damage-compression-induced tensile cracking." The ballistic test results indicated that firing two Specimen III projectiles completely disengaged all four lock bolts, demonstrating a significantly greater destructive efficiency than the other two specimens. The simulation model, established using the Mie-Grüneisen equation and SPH method, accurately predicted the stress evolution and failure morphology of the specimens, with a simulation-to-experiment von Mises stress peak error of less than 0.3%. The constructed comprehensive vulnerability index fully characterizes the damage properties of a material, providing theoretical and data support for the structural optimization and selection of composite medium projectiles.