13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- In this paper, numerical simulations are conducted on the perforation of Weldox460E steel plates struck normally by rigid conical-nosed projectiles and flat-ended projectiles. The modified Johnson-Cook constitutive relation and the Gruneisen equation of state which are valid for metals subjected to impact for large strains, high strain rates and high temperatures are implemented in ABAQUS/Explicit as a user-defined material model by means of a subroutine (VUMAT). Comparisons of the numerical results and the experiments show that the finite element models developed here are reliable. Based on the verified finite element model, numerical simulations are performed on the perforation of 6mm thick Weldox460E steel plates struck normally by conical-nosed projectiles with various cone angles, and the effects of various cone angles on the failure modes of metal plates and the energies absorbed for perforation are discussed. 2. Numerical simulation In this section, numerical simulations are conducted on the perforation of Weldox460E steel plates struck normally by rigid conical-nosed projectiles and flat-ended projectiles, the cone angles of which are equal to 180o as a special case of conical-nosed projectiles, using dynamic finite element code ABAQUS/Explicit. The targets was modelled using the modified Johnson-Cook constitutive relation which was implemented as a user-defined material model by means of a subroutine (VUMAT). 2.1. Finite element model Finite element model in this section is based on the experiments of normal impact of Weldox460E steel plates by conical-nosed projectiles and flat-ended projectiles [4][12]. The projectiles have a nominal mass (G) and diameter (d=2a) of 197g and 20mm, respectively. The total length (L) and the cone angle (θ) of the conical-nosed projectile is 98mm and 33o, and the total length (L) of the flat-ended projectile is 80mm. Projectiles were manufactured from Arne tool steel which has high strength and hardness, and it was observed that the plastic deformation of the projectiles was very small after perforation. In order to save CPU time and raise computational efficiency, projectiles are assumed to be rigid here. The target plates, having a span diameter (S=2R) of 500mm, were restrained at their periphery with respect to all degree of freedoms. Quarter models are used in the 3D finite element analysis, as seen in Fig. 1. (a) Conical-nosed projectile
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