Local impact effects of hard missiles on concrete targets

This paper presents the recent progress in formulating and modeling local impact effects in concrete targets struck by hard missiles. New research results in this area are also presented, these being part of the UK nuclear safety program against impact threats on concrete structures in nuclear power stations conducted under the auspices of Magnox Electric. Failure mechanisms are classified based primarily on experimental evidence. First, a collection of empirical formulae to predict the penetration depth, scabbing thickness and perforation thickness is presented in both Imperial and SI units. The current status of various design codes is then summarized. Based on a dimensional analysis, dominant non-dimensional parameters that may influence the local impact effects on concrete targets are obtained and then used to present some of the test data. Various nose shape factors are compared and a unique definition of the nose shape factor is suggested. Analytical models and numerical simulation methods for penetration are summarized. Criticisms are made for the current understanding of the effects of strain rate on the unconfined uniaxial compressive strength of concrete-like materials based on measurements by the split Hopkinson pressure bar technique.