Local effect of solid missiles on concrete structures

The appropriateness of the National Defense Research Council (NDRC) equations for penetration and back-face scabbing thicknesses are reevaluated using presently available test results. A nondimensional impact factor is introduced to improve the predictability of these equations. Penetration depths are estimated using NDRC, statistical NDRC, and the proposed Haldar equations. Although the NDRC equations predict the penetration depths for bullets reasonably well, they fail to do so for large missiles. The Haldar penetration equations are found to predict the penetration depths for all types of missiles. A similar relationship is proposed to estimate the scabbing depth directly by using the impact factor. However, this relationship is developed using only bullet data. For most large turbine missiles, the scabbing thicknesses need to be estimated indirectly using the information on the penetration depth. The applicability of the proposed penetration and scabbing thicknesses to large turbine missiles such as those postulated by the General Electric Corp. and West-inghouse, are discussed. The coefficients of variation for the estimation of penetration and scabbing thicknesses are large in all cases. Thus, in any probabilistic formulation like the one used for turbine missiles, they should be considered probabilistically.