Penetration of Nylon Ballistic Panels by Fragment-Simulating Projectiles1

The purpose of this report is to present evidence supporting the thesis that the major mode of penetration of nylon ballistic panels by fragment-simulating projectiles is a cutting, shearing mechanism: Shear forces required for yarn failure are usually less than tensile forces. Penetration is always at a slight angle, with the 90° edge of the FSP leading. Many yarn ends terminated in a smooth surface (in a tensile break the filaments break at random places along the yarn). Penetration of the cloth in certain experimental situations occur in a manner precluding tensile failure. The force required for nylon or Kevlar yarn failure is less for a rectangular leading surface than it is for a chisel-shaped leading surface.