13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- Figure 9. The perforation process of 6mm thick Weldox460E steel plate under normal impact by projectile with θ=140o through numerical simulation. As seen from Fig.6 to Fig.9, it is shown that projectile cone angle has significant effect on the perforation modes of 6mm thick Weldox460E steel plates and that for smaller cone angles plates fail by ductile hole enlargement, for medium cone angles plates fail by petalling and for larger cone angles plates fail by discing or plugging. Fig.10 shows the numerical residual velocity Vr for 6mm thick Weldox460E steel plates struck normally by conical-nosed projectiles with θ=20o, 60o, 100o and 140o. Figure 10. Numerical residual velocity Vr for 6mm thick Weldox460E steel plates struck normally by conical-nosed projectiles with various cone angles As shown in Fig.10, the residual velocity of projectile is closely related to the failure mode of the target plate, and the residual velocity is not always decreasing sensuously with the increment of the projectile cone angles. The residual velocities for various projectile cone angles θ=20o, 60o, 100o and 140o in present simulations are 88m/s, 93m/s, 72m/s and 90m/s, respectively. The energy dissipated for the perforation of target plate failed in ductile hole enlargement with global deformation struck normally by conical-nosed projectile with θ=20o is larger than that for the perforation of target plate failed in petalling with global deformation struck normally by conical-nosed projectile with θ=60o. The energy dissipated for the perforation of target plate failed in discing with global deformation struck normally by conical-nosed projectile with θ=100o is larger than those by projectile cone angle θ=20o and 60o, and obviously larger than that for the perforation of target plate failed in plugging with global deformation struck normally by conical-nosed projectile with θ=140o. It is found that the energy dissipated by discing is maximum.
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