Penetration of fastener projectiles into construction materials

The normal impact, penetration of both projectile and fastener into soils, rocks, and concrete at low velocities has been investigated using theoretical, experimental, and numerical approaches under axisymmetric conditions. The projectile penetration theory is developed on the basis of the existing cylindrical cavity expansion theory with target materials approximated by compressible locking behaviour in a hydrostatic state and elastic-plastic, linear strain- hardening behaviour in a shear state. This theory is one-dimensional with respect to wave propagation in a radial direction. Impact penetration experiments have been performed using a cartridge-operated tool firing the steel fasteners into sandstone and concrete targets. The associated pull-out problem has also been studied. Damage to both fastener and target caused by the impact penetration is assessed using an optical microscope. Finite element programs have been employed to investigate the penetration process of the projectile, and eventually to simulate the process of fastener penetration. The dependency of the penetration process on impact velocity, projectile nose shape, projectile-target interfacial friction, and target material properties have been studied for a variety of impact conditions. Comparisons of results obtained from all three approaches are made for cases in which data are available. Agreements reached are reasonably good.