Fragment impact of cased explosives was studied by experimental testing and numerical modeling. The objective was to obtain a better understanding of detonation phenomenon and to determine if case explosive of a specific warhead configuration will detonate when subjected to impact of an 80 - gram Fragment Simulated Projectile (FSP) at various impact velocities. The stress was measured on the backside of the steel plate in a ballistic test uslng an experimental technique. Relationship between impact velocity against a warhead casing and presure induced between the warhead casing and the explosive was determined. Numerical modeling of this experiment was performed using a hydrodynamic code, to validate the results of the experiment in predicting the impact pressure on the backside of the steel plate. At the end, numerical modeling of a 80 FSP impacting a steel plate, which was backed by unconfined cased H6 explosive was used to predict detonation of the explosive. Of the impact velocities studied, ranging from 235 m / s to 2,225 m / s, only impact velocity of 2,225 m / s resulted in severe detonation.