Probability Calculations for Insensitive Munitions Tests

摘要

Warhead fragment impact angles are becoming more important as computations are being utilized to model fragmentimpact and subsequent dynamic response of the target. Insensitive munitions (IM) test results also depend on the impactangles. In some cases, high-speed film or x-ray is available to determine the impact angles. However, in many cases, theimpact angle of a fragment must be estimated based on the assumption of random tumbling and is given in terms of theprobability of a particular impact angle range occurring.The probability of an impact angle occurring for some fragment shapes has been reported previously. Earlier probabilitycomputations required Monte Carlo methods. This author’s recent work described an analytic technique to obtain theprobability of a hexahedron based on a surface area ratio of a sphere.This paper briefly reviews this calculation for one cube and uses this result to determine the probability of the minimumangle for three impacting cubes. Both configurations are important because they are IM test configurations described inMIL-STD-2105B. Finally, this work applies the analytic probability technique to the U.S. Proposed NATO InsensitiveMunitions Test Fragment under the assumption that it is randomly tumbling. Comparisons are then made between theresults.