Experts design bomb-proof bag for luggage compartment in planes

A bag, which can protect planes from bombs in passenger luggage, has been developed by an international team of scientists, including academics from the University of Sheffield working within University spinout company Blastech Ltd.

The bag, named the Fly-Bag, features multiple layers of novel fabrics, composites and coatings and is designed to be filled with passenger luggage and then placed in the hold of a plane. If there were a bomb in the luggage in the bag which exploded during the flight, the resulting blast would be absorbed by the bag due to its complex fabric structure, preventing damage to the plane.

Fundamental to the design of the bag is the internal elastomeric coating and impregnation of fabric with Shear Thickening Fluids (STF).

Elastomers are very low stiffness, high failure strain materials, often used as adhesives, sealants or in structures where high strains are expected. An elastomer was developed to provide a gas seal in the bag at very high strain rates and very high deformations, whilst resisting flame and heat.

STFs work by increasing in viscosity in response to impact. A simple STF can be made from mixing cornflour with water. Providing quantities are correct, it would be possible to roll this simple STF into a ball that will bounce on hard surfaces but return to a fluid once it is left alone.

Under normal circumstances, the particles in STFs repel each other slightly, however following sudden impact, the extra energy in the system proves stronger than the repulsive forces, causing the particles to clump together in structures called hydroclusters, which bump into each other, consequently thickening the fluid.

This unusual behaviour of STFs has already generated significant commercial interest and STFs are being considered to improve body armour designed to protect the wearer from weapons such as knives and bullets.

In the case of the Fly-Bag, the STF is coated onto the yarn of the fabric and as the fabric comes under strain, shearing forces between the yarns cause the STF to thicken, temporarily increasing the stiffness of the fabric, reducing the total deformation.

Hardened luggage containers (HULD) have been developed to deal with bombs hidden in passenger luggage, but these containers are heavier and more costly than conventional equivalents and are only suitable for wide body aircraft.

It is expected that the Fly-Bag will be on the market in one to two years, although cost would depend on a range of variables, such as the structure of the plane.

Team member Dr Jim Warren from the University of Sheffield's Department of Civil and Structural Engineering, said: "The use of explosives on aircrafts has had a renaissance in recent years, with recent attempted attacks coming not just from passengers, but also as loaded freight. Since weight and operational flexibility is key for aircraft operators, this low weight, removable solution would seem to be a paradigm shift in the hardening of aircraft structures."

Notes for Editors: The Faculty of Engineering at the University of Sheffield is one of the largest in the UK. Its seven departments include over 3,000 students and 800 staff and have research-related income worth more than £40M per annum from government, industry and charity sources. The 2008 Research Assessment Exercise (RAE) confirmed that two thirds of the research carried out was either Internationally Excellent or Internationally Leading. The latest National Student Survey (NSS) shows our students to be some of the most satisfied in the country with 93 per cent of students satisfied and 91 per cent of graduates securing highlevel employment or further study places.

The Faculty of Engineering has a long tradition of working with industry including Rolls-Royce, Network Rail and Siemens. Its industrial successes are exemplified by the award-winning Advanced Manufacturing Research Centre (AMRC) and the new £25 million Nuclear Advanced Manufacturing Research Centre (NAMRC). To find out more, visit the link below.

Blastech Ltd, operates within the faculty of Engineering, and is owned by its academics and the University. Blastech Ltd undertakes rapid-turn around, or high fidelity testing for Ministry of Defence, DSTL, Qinetiq, the security service, BAE and other security oriented organisations. Blastech works mainly in physical security.

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