Frangible Ammunition Containers

The objective of this Phase i work is to develop and demonstrate that a frangible munitions container, one capable of passing an Insensitive Munitions (IM) cook-off test, can be presuced with a low-cost modification to the container can. The critical problem associated with existing containers is the rapid development of combustion gases and high pressures which cause the container to literally explode creating fragments which, in turn, promulgate the fire and create ancillary explosions. The design goal is thus to provide a modification to the can that will allow venting of the combustion gases without the creation of fragment. The innovative solution provided herein relies upon the use of fracture mechanics theory and analysis to define the geometry of a crack starter machined into the surface of the can. It is informative to note that within the time period that the pressure in the container rises to critical levels (approximately 10 milliseconds), a properly configured crack starter can cause the generation of over 31 feet of crack surface. This significant level of crack formation allows for more than sufficient venting to prevent explosion and fragment formation. The key element of the innovative approach relies upon the use of state0or-the-art fracture mechanics technology and stress analyses to define the precise dimensions of the crack starter. Also, since the number of potential crack starter geometries is virtually unlimited, it is necessary in this research, to define the configuration most efficient and reliable. It is noted that this approach, once demonstrated, provides an extremely low-cost and reliable sloution to the problem of venting. Phase I work will develop and demonstrate the feasibility of the innovative appraoch providing the Army with a highly effective system with concomitant low risk.