Estimating sensitivity with the Bruceton method: Setting the record straight

Abstract

Accurate estimates of sensitivities of energetic materials are crucial for ensuring safe production, transport, usage and destruction of explosives. When estimating sensitivities, researchers most commonly follow the NATO standard guidelines (STANAGs), in which the Bruceton method is imposed. Introduced in 1948, this method contains (i) an experimental design for choosing which stimulus levels to measure at and (ii) a recipe for computing sensitivity estimates. Although the former experimental design is supported by both theory and simulations, few modern researchers are aware that the latter recipe was only intended as a pen-and-paper approximation of the maximum likelihood estimates, which are easy to compute today. The persistent use of this outdated approximation has led to many unfortunate misconceptions amongst users of the Bruceton method, including the rejection of many perfectly valid data sets and neglect of uncertainty assessments via confidence intervals. This is both dangerous and unnecessarily wasteful. This paper sets the record straight and explains how researchers should estimate sensitivity via maximum likelihood estimation and how to construct confidence intervals. It also shows explicitly how wasteful said approximation is via both simulations and with real data.