Low-Velocity Perforation of Mild Steel Rectangular Plates With Projectiles Having Different Shaped Impact Faces

This article studies the perforation of mild steel square and rectangular plates struck normally by cylindrical projectiles having blunt, hemispherical, and conical impact faces. Experimental results are obtained in a drop hammer rig for the perforation of $4mm$ and $8mm$ thick plates struck by relatively heavy projectiles weighing between $11.9kg$ and $200kg$ and traveling at an initial velocity up to about $13m∕s$⁠. The plates were struck at the center and at several positions near the fully clamped supports. The effect of the aspect ratio on the perforation energies of rectangular plates is examined, and comparisons are made with the perforation behavior of fully clamped circular plates. The predictions of several empirical equations are compared with the corresponding experimental values of the perforation energies. Simple design equations are also presented for predicting the maximum permanent transverse displacements of square plates prior to any cracking or perforation.