Sheffield Uni engineers having a blast

Engineers at Sheffield University are launching a new laboratory to explore the blast impacts of compact explosives at close range.

Improvised Explosive Devices, or IEDs, became a prominent weapon in 21st-century assymetric warfare and were regularly used by insurgents in Iraq and Afghanistan. But the physics of the type of explosions caused by IEDs is not as well understood as larger and more distant blasts, which have been studied and modelled in greater depth.

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Backed by £1.3m of government funding, the new Sheffield laboratory will provide a safe environment in which explosive, fragment and ballistic tests can be conducted whilst allowing the highest possible spectrum of data to be collected. The data could inform ways to protect critical infrastructure and urban environments, such as buildings and vehicles, against explosive threats from close proximity.

“The grant provides a step-change in our capabilities to investigate the region very close to an explosive detonation,” said Dr Sam Clarke, senior lecturer in Geotechnical Engineering at Sheffield University.

“The combination of ultra-high-speed cameras, thermal imaging and flash x-ray diagnostics, combined with our current capabilities in load characterisation will give us a unique capability to push forward research into protecting people from devastating blast effects.”

Most experimental research on the impact of blasts uses highly simplified geometric scenarios. However, as real-world explosions often occur in more complex settings, such as densely populated cities and urban areas, there is a need to better understand how explosives interact with the materials and structures that surround them. This includes the detonation products and resulting fragments produced by an explosion that pose a major risk to life.

The blast laboratory at Sheffield will be able to deliver this crucial insight using a new reinforced concrete blast chamber, capable of withstanding a 1kg explosive internal blast. The chamber will allow the deployment of a protected blast diagnostic system, consisting of dual ultra-high-speed cameras for digital image correlation of structural responses to explosions, a high-speed mid-wave infrared camera for analysing the temperature and spectroscopy of explosions, and four-channel flash x-ray for internal diagnostics of how materials respond to blasts.

A separate fragment launcher will also be able to fire projectiles into the chamber, enabling ballistic interactions with structures and materials to be studied in isolation of the blast where necessary. The Sheffield group will feed its insights through to academic and industrial partners who have experience in designing blast protective systems, in order to optimise blast-resistant materials.