Critical impact energies for scabbing and perforation of concrete target

In this paper, the influences of the relative target thickness (H/d) on those critical impact energies, at which local damage of various forms in concrete targets are initiated, are explored. The empirical formulae developed in the R3 Impact Assessment Procedure [BNFL, 2003. Reinforced Concrete Slab Local Damage Assessment, R3 Impact Assessment Procedure, vol. 3, Appendix H. Magnox Electric plc & Nuclear Electric Limited] are rationalized by different methods. A dimensional analysis was conducted to identify influential non-dimensional numbers, which were subsequently employed in the analyses of the experimental results relevant to scabbing and perforation by flat nosed missiles. The relationships between the non-dimensional impact energy frac(1, 2) M V₀² / ( d³ f ) at failure and the non-dimensional target thickness H/d are presented for all of the relevant experimental data in the "World Impact Data" collection [Bainbridge, P., 1988. World Impact Data-S.R.D. Impact Database Version Pre 3i, CCSD/CIWP(88)107(P)]. This collated hundreds of experimental data on local damage in concrete targets due to missile impact from various sources of nuclear industries, as well as experimental data from the UK electrical power industry used to develop empirical formulae in the R3 Impact Assessment Procedure [BNFL, 2003. Reinforced concrete slab local damage assessment, R3 Impact Assessment Procedure, vol. 3, Appendix H. Magnox Electric plc & Nuclear Electric Limited]. The experimental data in Bainbridge [Bainbridge, P., 1988. World Impact Data-S.R.D. Impact Database Version Pre 3i, CCSD/CIWP(88)107(P)] are compared with empirical and semi-empirical formulae for scabbing and perforation in order to examine the effects of H/d on the critical non-dimensional impact energy for these two local failures. An analytical formula based on a penetration-plugging model is employed to give the relationship between the critical impact energy and target thickness for perforation by a flat-ended projectile. Comparisons between these formulae and experimental data are presented.