Blast and Impact Diagnostics Laboratory

This grant will provide a unique blast and impact diagnostics laboratory open to UK universities and industry. The aim of the laboratory is to provide a safe environment in which to conduct high explosive and fragment/ballistic tests, whilst allowing the highest possible spectrum of data to be collected. Multi-parameter, multi-spatial diagnostics are crucial to our understanding of the physical processes that govern these events and will provide validation data for the current effort worldwide in the development of mitigation/protective systems and the numerical modelling of such processes, with the goal of increasing levels of protection and saving lives.

The aim of the laboratory is to provide diagnostic capabilities across a range of scales where traditional large-scale testing is either impossible or very expensive. There is still a fundamental lack of understanding of the mechanisms which generate the loading very close to an explosive, and perhaps, more importantly, the effect that both materials and structural systems can have on the developed load. The laboratory will provide ultra-high-speed optical diagnostics of both the expanding explosive fireball and the resulting interactions with adjacent structural systems. The dual cameras will allow the deflection of these systems to be quantified, providing performance metrics and validation data.

Most experimental research on the measurement of blast loading uses highly simplified geometric scenarios. But real-world blast threats must be considered in complex settings, such as dense urban cityscapes. Numerical modelling tools are regularly used to predict loading and damage in these scenarios but there is very little high-quality experimental data available to validate these model outputs and we do not know how the detail of the geometry affects the loading. In fact, this problem is ideally suited to research at small-scale, making use of well-established scaling laws to inform practical full-scale analyses. The ultra-high-speed cameras, combined with image tracking approaches will allow us to track the shock fronts through 3D printed models of real urban spaces generating low cost, high fidelity data with which to appraise modelling approaches.

Computational modelling of blast and ballistic events, from detonation to contact with targets, have made huge advances in the past few decades. However, experimental research has not kept pace with the development of powerful but often unvalidated computational modelling tools. Detailed experimental investigation that could transform both the quantitative and qualitative understanding of these events are rarely even considered, let alone conducted, because of the high speeds and intense loads involved. The new laboratory, combined with the existing capability at the University of Sheffield in the recording of near-field blast loading (MaCE EPSRC grant), will provide validation data to interrogate the ability of numerical models to both predict blast/ballistic loading and the response of materials/structures to this loading.

These benefits will be delivered by a combination of ultra-high-speed digital image correlation to determine target response, along with the thermometry/spectroscopy of the explosive fireball/impact, and flash x-ray to understand the often-hidden internal mechanics. With better knowledge of blast and ballistic effects comes the ability to develop new and innovative systems for the protection of vehicles (aircraft and armoured platforms), personnel (demining/counter-improvised explosive device equipment and body armour), and structures (critical structural elements, buried infrastructure) where the traditional defence of maintaining distance between
an explosive threat and an object is not possible.