ON THE BALLISTIC PERFORMANCE OF METALLIC MATERIALS

The paper presents a ballistic performance index for metallic armour m aterials in terms of the commonly determined mechanical properties suc h as strength and modulus. The index is derived using an energy-balanc e approach, where the kinetic energy of the projectile is assumed to b e absorbed by the elastic and the plastic deformation involved in the penetration process as well as the kinetic energy imparted to the targ et material during deformation. The derivation assumes two distinct st ages to exist during the penetration of the projectile. At the strikin g face of the armour, the material is assumed to flow radially in a co nstrained deformation region but longitudinally at the rear surface le ading to typically observed bulging of the armour without constraint. The index is validated using the available experimental and empirical data obtained in the case of small arm projectiles for an impact veloc ity of about 800 m/sec. This index is expected to facilitate the devel opment of metallic armour, since the number of the ballistic experimen ts can be reduced significantly and only the promising materials need to be considered.