A model to estimate the response of confined explosives after projectile penetration or perforation

TNO Defense, Safety and Security in cooperation with the Dutch Command Materiel and IT agency (COMMIT) of the Ministry of Defense (MOD) is investigating the munition responses when subjected to small arms weapon impact, SCJ impact, sympathetic reaction scenarios etc. The investigation comprises in-service munition testing, simulations using munition and platform vulnerability tools, and mitigation methods research. In the case of a severe response, supported by simulations, mitigation methods are developed for the munitions that form a danger to personnel and materiel.
An engineering shock model, based on the Energy fluence parameter E, has been developed in the past and the model has been improved for bare explosives and flyer impact, recently. The model showed to be very useful in vulnerability as well as in lethality studies and is being implemented in several codes, such as the platform vulnerability code RESIST and the stand-alone code VIOLENT.
The projectile penetration/perforation response model is the next tool and is still under development. For the individual steps in the mechanism of this threat, models are being developed, amended or improved to calculate the response of a munition after a hit. Once the internal pressure due to the burning reaction is known, the velocity of the casing, driven by the internal pressure, and the fragmentation of the casing can be estimated, even for lower order reactions. For some of these steps in the mechanism, the method will be explained in more detail and some examples will be presented for internal pressures near the detonation pressure and for pressures that 1 to 2 orders of magnitude lower.