Sympathetic reaction TEMPER simulations for 155 mm shell filled with MCX-6100 composition

IM classification of munitions requires testing according to STANAG 4439 (1). All tests have to be performed unless the Threat Hazard Analysis shows that specific threats in the STANAG do not occur in the life-cycle of specific munitions. In some nations full scale tests may be replaced by small scale testing accompanied by simulations. In this report results from small scale testing of the explosive composition MCX-6100 have been used as input for Sympathetic Reaction simulations with the MSIAC TEMPER software. The munitions we have studied are 155 mm shells. MCX-6100 is a melt-cast composition to be used as main filler in this munition. TEMPER simulations for sympathetic reaction “One -on -One” on 155 mm shell filled with MCX-6100 CH 6079/13 have been performed with the same filler in both donor and acceptor. Variables studied are: 4 different shock sensitivities, 36.4, 47.5, 53.4 and 58.5 kbar and 4 different compositions, Top, Middle, Bottom and nominal content, and 1 filling density, measured density. Cheetah calculated densities (TMD) are not included. Therefore effects of porosity were not included, only the effects of sedimentation. 13 scenarios have been studied. Required acceptor shell thickness for 155 mm filled with different MCX-6100 compositions with equal shock sensitivity due to sedimentation varies by 1 mm or less for the same response. In addition sedimentation gives some small differences, 1-2 mm in the donor shell thicknesses that produce the WC-fragments. The overall conclusion is that the effect of sedimentation has only minor influence on the acceptor properties. The shock sensitivity of the MCX-6100 filling, however, has significant influence on the required shell thickness in the acceptor to give a no reaction response. Going from a low (58.5 kbar) to a high shock sensitivity (36.4 kbar) filling an increase of 8 mm in shell thickness is required to retain a no reaction response. The increases in shell thicknesses for Top, Middle and Bottom composition are the same. Therefore the acceptor response in Sympathetic Reaction is mainly controlled by the MCX-6100 compositions shock sensitivity. For the four (Top, Middle, Bottom and Nominal) compositions of MCX-6100 with shock sensitivity 58.5 kbar a no reaction response requires a shell thickness of 8-9 mm, with shock sensitivity 53.4 kbar, 10 mm is required, with shock sensitivity 47.5 kbar 12 mm is required and with shock sensitivity 36.4 kbar 16-17 mm is required. To pass the IM requirement STANAG 4439 requires the Sympathetic Reaction test to result in type III reaction, deflagration response. To fulfil this IM requirement the shock sensitivity of the MCX-6100 filling in a 155 mm shell should be +50 kbar or better. This is a shock sensitivity of MCX-6100 fillings which should be possible to obtain with optimal casting quality.