Stop using limiting stimuli as a measure of sensitivities of energetic materials

TL;DR

This paper critiques the use of limiting stimuli in explosive sensitivity testing, demonstrating its unreliability and proposing alternative, statistically sound methods validated through simulations and real data application.

Contribution

It shows that limiting stimuli are unreliable for sensitivity estimation and introduces three alternative methods with validation through simulations and real-world data.

Findings

Limiting stimuli do not reliably measure sensitivity.

Alternative methods outperform the 1-In-6 test in simulations.

Application to PETN data demonstrates practical utility.

Abstract

Accurately estimating the sensitivity of explosive materials is a potentially life-saving task which requires standardised protocols across nations. One of the most widely applied procedures worldwide is the so-called '1-In-6' test from the United Nations (UN) Manual of Tests in Criteria, which estimates a 'limiting stimulus' for a material. In this paper we demonstrate that, despite their popularity, limiting stimuli are not a well-defined notion of sensitivity and do not provide reliable information about a material's susceptibility to ignition. In particular, they do not permit construction of confidence intervals to quantify estimation uncertainty. We show that continued reliance on limiting stimuli through the 1-In-6 test has caused needless confusion in energetic materials research, both in theoretical studies and practical safety applications. To remedy this problem, we consider three well-founded alternative approaches to sensitivity testing to replace limiting stimulus estimation. We compare their performance in an extensive simulation study and apply the best-performing approach to real data, estimating the friction sensitivity of pentaerythritol tetranitrate (PETN).