To study the property of shielded composition B initiated by a ?30mm shaped charge jet,the numerical simulation for the process of shaped charge jet formation,penetrating and shock initiating the shielded composition B was studied by means of nonlinear finite element analysis software LS-DYNA. The parameters,such as jet velocity,diameter and impact energy through the different shield steel plates in the thickness of 50-75 mm were obtained. Also,the critical initiation thickness of shaped charge jet to shiel...