Perforation of 12mm thick steel plates by 20mm diameter projectiles with flat, hemispherical and conical noses: Part I: Experimental study

Structural Impact Laboratory (SIMLab), Department of Structural Engineering, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
International Journal of Impact Engineering (Impact Factor: 2.2). 01/2002; 27(1):19-35. DOI: 10.1016/S0734-743X(01)00034-3


Projectiles with three different nose shapes (blunt, hemispherical and conical) have been used in gas gun experiments to penetrate 12 mm thick Weldox 460 E steel plates. Based on the experimental results, the residual velocity curves of the target material were constructed and compared. It was found that the nose shape of the projectile significantly affected both the energy absorption mechanism and the failure mode of the target during penetration. The ballistic limit velocities were about equal and close to 300 m/s for hemispherical and conical projectiles, while it was considerably lower for blunt projectiles. Blunt projectiles caused failure by plugging, which is dominated by shear banding, while hemispherical and conical projectiles penetrated the target mainly by pushing the material in front of the projectile aside. Also, the residual velocity curves were influenced by nose shape, partly due to the differences in projectile deformation at impact. The experimental study, given in this part of the paper forms the basis for explicit finite element analysis using the commercial code LS-DYNA presented in Part II of the paper.

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    • "The material model encompasses not only the stress–strain relationship at different strain rates but also accumulation of damage [23] [24] [25] [26] [27]. To describe ductile fracture, Johnson and Cook proposed a model including the effects of stress triaxiality, temperature and strain rate on failure strain [23]. "

    Full-text · Article · Nov 2015 · Materials Science and Engineering A
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    • "Finally, the fracture is propagated through the necking circle while the indenter pushes the plate. For specimen C20 (Fig. 5b), the indenter provokes a local shear ring at its perimeter which is named shear circle or shear banding [8] [9]. These specimens suffer small local indentation and plastic deformation outside the shear circle. "
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    ABSTRACT: Experimental and numerical results of drop weight impact tests are presented, examining the plastic response and the crack initiation and propagation of small-scale clamped rectangular aluminium plates laterally impacted by different indenter shapes. The experiments are conducted using a fully instrumented impact testing machine. The shape of the deformation of the specimens and the process of initiation and propagation of the material fracture is presented. The obtained force-displacement responses show a good agreement with the simulations performed by the LS-DYNA finite element solver. The strain hardening of the material is defined using experimental data of quasi-static tensile tests and the critical failure strain is evaluated measuring the thickness and the width at fracture of the tensile test pieces. The results show that the absorbed energy to perforate the specimens is highly sensitive to the shape of the striker. Thus, the crack propagation for each striker type is analysed in terms of the force-displacement response. The failure modes are described by the matrix of the infinitesimal strain tensors and the shape of the deformation of the failing elements.
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    • "The main advantages of the Lagrangian finite elements formulation [14] is an intuitive modeling of an experimental configuration by a deformable geometry, a large number of implemented material models, as well as many examples describing successful applications, [7] [8] [9] [10]. The main criticism of the Lagrangian FEM is a large mesh distortion, [15] [16], since the heavily deformed elements may cause numerical difficulties leading to the negative volume of elements. "
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    ABSTRACT: The paper describes the ballistic impact test, in which fragment simulating projectiles (FSPs) of a 20-mm-diameter have been used against 40-mmthick plates made of an aluminum alloy AA7020-T651. To perforate plates, the projectiles must have reached a velocity higher than 890 m/s. Based on the performed ballistic test, the plugging failure mode is numerically modeled using the LS-DYNA software package. Results obtained due to the calculations in the Finite Element Method (FEM) are compared with the results from the Smoothed Particle Hydrodynamics (SPH). A condition of geometrical similarity between the target deformed experimentally and its numerical representation is introduced to evaluate the performed simulations.
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