Application of porous metal foams in hybrid armor systems

摘要

The U.S. Army has a strong interest in developing lightweight integral armor for ballistic protection. An advanced hybrid armor system was designed and fabricated with aluminum foam inserts between the strike plate and the backing plate. This new armor design utilizes the shock wave attenuation capability, high specific structural stiffness and low density of closed cell aluminum foams to enhance the overall ballistic performance. One-dimensional (1-D) and three-dimensional (3-D) finite element models of multi-layer armor containing aluminum foams impacted by a 20-mm fragment simulation projectile (FSP) have been developed to investigate the dynamic deformation of aluminum foam. Ballistic tests were conducted and the results indicated that armor targets incorporating aluminum foams have advantageous effects in shielding the shock wave generated by the projectile impact, effectively preventing premature failure of the backing plate. The ballistic stress wave experiments showed that the metal foam is effective in absorbing the impact-induced stress wave, and may thus delay or even prevent the onset of brittle fracture of ceramic layers and improve system performance. Evaluation of the dynamic deflection behind the targets showed that the metal foam was effective in containing rearward deformation of ballistic targets. Thus, metal foams may be useful for controlling backface deformation and spalling, and thereby provide added protection to equipment and personnel. These attributes of the aluminum foam used in hybrid armor systems add a new dimension to the design and effectiveness of lightweight armor systems for future armored vehicles.