An investigation of the constitutive behavior of Armox 500T steel and armor piercing incendiary projectile material

A detailed investigation has been carried out for studying the constitutive behavior of Armox 500T steel and armor piercing incendiary projectile (API) material under varying stress state, strain rate and temperature. The characterization of Armox 500T steel showed increase in its strength with increase in stress triaxiality as well as strain rate. Increment in temperature, on the other hand, induced significant increase in the material ductility while reducing its strength. The API projectile material remained insensitive to stress-triaxiality and strain rate; however, it was highly sensitive to thermal effects. Results thus obtained from experiments on the specimens of both the materials were subsequently employed for calibrating the material parameters of Johnson–Cook (JC) flow and fracture model. The calibrated JC model for Armox 500T steel has been validated by numerically simulating the high strain rate tension tests performed on split Hopkinson pressure bar apparatus. The ballistic experiments were carried out wherein 8 and 10 mm thick Armox 500T steel target plates were impacted by 7.62 and 12.7 API projectiles respectively at a normal incidence with a velocity of nearly 830 m/s. The results of the ballistic tests were reproduced through finite element simulations performed on ABAQUS/Explicit finite element code employing calibrated JC model for the target as well as the projectile material. Experimental and numerical findings with respect to failure mechanism and ballistic resistance of the target are presented and discussed. It is seen that the computed failure modes and residual velocities accurately matched the experiments. Further, the ballistic limit of the target material was obtained numerically and the values obtained were validated through the Recht–Ipson empirical model.