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a b s t r a c tIn this paper a study is presented on the experimental and numerical analysis of the failure process of mild steel sheets subjected to normal impact by hemispherical projectiles. The experiments have been performed using a direct impact technique based on Hopkinson tube as a force measurement device. The tests covered a wide range of impact velocities. Both lubricated and dry conditions between specimen and projectile have been applied. Different failure modes for each case were found. For lubricated conditions a petalling was observed, whereas for dry conditions a radial neck along with a hole enlargement reduces the formation of petalling. The perforation process has been simulated by the application of 3D analysis using ABAQUS/Explicit FE code. The material behavior of the circular specimen was approximated by three different constitutive relations. The main task was to study the influence of the material definition on the response of the sheet specimen with special attention to the failure mode.

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In this paper, a numerical study of normal perforation of thin steel plates impacted by different projectile shapes is reported. The numerical simulations of this problem have been performed using a finite element code, ABAQUS Explicit with a fixed and an adaptive mesh for the plate. To define the thermoviscoplastic behaviour of the material constituting the plate, the Johnson Cook model has been used. This homogeneous behaviour has been coupled with the Johnson Cook fracture criterion to predict completely the perforation process. Three kinds of projectile shape (blunt, conical and hemi spherical) have been simulated with a large range of impact velocities from 190 to 600 m/s. The analysis considers the influ ence of adiabatic shear bands, plastic work and the gradient of temperature generated in the plate. The numerical results predict correctly the behaviour projectile plate in agreement with experimental data published by other authors.