(501b) Numerical Simulation of Munitions Response for Fragment IMPACT

The primary purpose of full-scale Insensitive Munitions (IM) testing is to establish the response of a munition to a variety of stimuli under specified conditions. This information can be used to determine compliance with the national IM policy, which is a strict requirement in many NATO countries. This ensures improved weapon safety and decreased risk for the occurrence of unplanned hazardous events. Numerous standardization agreements (STANAGs) [1] outline the various Insensitive Munitions (IM) threats simulating the hazards that munitions are commonly exposed to on the modern battlefield. These threats include: sympathetic detonation, shaped charge jet impact, bullet and fragment impact, and slow and fast cook-off. Advances in the state-of-the-art physics-based models have created an opportunity for the weapon development community to use these tools effectively to screen design candidates and to predict full scale test outcome. The overall modeling and simulation capability addresses a wide range of physics phenomena that relate to the energetic material, its behavior when exposed to threat stimuli, and ultimately its final response that determines the outcome of an IM event. The objective of this work is to develop a numerical model using hydro code that accurately simulates a fragment impact event for tested projectile. The model will predict the shock pressure that the round undergoes due to the impact insult. Various fragment velocities were investigated in order to estimate at which velocity the shock pressure is above the threshold value for detonation obtained from the LSGT (Large Scale Gap Test). This result will be classified as a “fail” and it will be assumed the projectile will not survive the shock from fragment stimuli that will mark the threshold value of fragment velocity. The effect of aim point variation on the shock pressures transmitted to the explosive has also been analyzed computationally. The planar impacts at two different aim points were modeled, one at the main fill and other at the booster area.