Low Velocity Perforation Design Of Metal Plates
Free (open access)
N. Jones & R. S. Birch
This article examines some recent experimental test data on the perforation of mild steel plates having thicknesses 2 ≤ H ≤ 8 mm and struck by relatively heavy masses travelling up to about 13 m/s. The plates are fully clamped around circular, square and rectangular boundaries and struck by projectiles having blunt, conical and hemispherical impact faces. It transpires that the dimensionless perforation energies are smallest for the plates struck by the blunt-faced projectiles and largest for the hemispherical ones. The perforation energies are greatest at the plate centre and are smaller near to the supporting boundaries. These latter effects are captured in an empirical equation for the dimensionless perforation energy. This equation provides a lower bound to almost all of the test data on the different plate geometries and impactor shapes and is, therefore, a useful tool for design purposes. Keywords: perforation, impact, circular plate, rectangular plate, blunt, conical, hemispherical impactors. 1 Introduction Many empirical equations for the impact perforation of ductile metal plates have been developed over the years since Robins studied the problem in 1742. However, most of these equations have been obtained using experimental data from high velocity tests with relatively light missiles which are of particular interest for military engineers. Nevertheless, there is a large class of practical industrial impact problems which involve heavy masses travelling at relatively low velocities. These impact loadings produce global deformations (e.g., large transverse displacements of the plating) prior to perforation which contrasts with the local shear failures, which often occur at the high impact velocities associated with the existing empirical equations.
perforation, impact, circular plate, rectangular plate, blunt, conical, hemispherical impactors.