Projectile Impact on Honeycomb Sandwich Plates

An investigation has been conducted to experimentally determine the ballistic limits, exit velocities and perforation features of honeycomb sandwich plates. Two flexible aluminum cellular plates with different unit weights, 15.9 mm (5/8 in) thick, served as cores; facings cemented to each side of these cores consisted of two thicknesses of an aluminum alloy or ABS. The curved cells of the cores had an average diameter of 7.6 mm and wall thicknesses of 0.048 of 0.064 mm. Ballistic limits of the facings were also obtained. Hard steel strikers of 12.7 and 6.35 mm diameter and cylindrical, cylindro-conical and spherical shapes were fired at these targets in the velocity range from just below to well above the minimum perforation speed. The principal dissipative mechanism of the sandwich was the perforation resistance of the facings. For identical covers, ballistic limits or terminal velocities of all projectiles fired were indistinguishable, with experimental error regardless of which of the two core types was employed. Beyond an initial slightly concave downward curvature just beyond the ballistic limit, the curves of terminal versus initial velocity were essentially linear, as has been generally observed for homogeneous plastic or metallic targets in previous investigations.