An analytical model for the penetration of flat-nosed long rods into semi-infinite concrete targets

An analytical model is presented herein on the penetration of a flat-nosed long rod into a semi-infinite concrete target based on the previous theoretical studies and experimental observations. The nose shape of the flat-nosed long rod in deformable penetration state is assumed to be a circular arc and the length of plastic region of the long rod in hydrodynamic penetration is taken into account. The behavior of an erosive penetrator is further divided into two penetration stages (namely semi-hydrodynamic penetration and hydrodynamic penetration) and a new critical impact velocity (i.e. erosive velocity) is derived to characterize the beginning/incipient erosion in accordance with plastic wave propagation theory. According to the new theoretical considerations, the relationship of dimensionless instantaneous mushrooming head radius versus impact velocity is rewritten and the method for predicting semi-hydrodynamic penetration tunnel radius is proposed. It transpires that the present model predictions are in good agreement with available experimental results for the penetration of flat-nosed long rods into semi-infinite concrete targets in terms of penetration depth, penetration modes, penetration tunnel size, residual mass and residual length.