Optical diagnostics in near-field blast measurements

The understanding of structural and material response to air-blast loading is a necessary prerequisite to the development of effective blast protection and mitigation systems. Computational tools have advanced significantly, enabling extensive simulations of the loading and ensuing structural response that occur as the result of an explosive detonation. Experimental techniques, however, have lagged behind in providing robust, high fidelity measurements regarding the transient response and spatial distribution of specific impulse across a structure.

This article discusses recent advances in these techniques at the University of Sheffield and describes the results that can be obtained. It details proof of concept testing via a bilateral collaboration between the UK and South Africa involving single-blind experimentation using high-speed imaging, digital image correlation and comparisons with results from near-field blast experiments performed at the University of Sheffield CoBL facility.

Secondly, it describes some of the continued developments since the success of those early trials, resulting in a new optical diagnostics for blast capability at the University of Sheffield. This article demonstrates the usefulness of improved diagnostics and techniques in blast experiments and shows the efficacy and versatility of high-speed imaging and DIC for determining impulse profiles and transient structural behaviour. Ultra-high speed imaging is also shown to be a useful tool for visualising detonation fronts in explosive charges and the expanding fireball.