31 Jul 2017

Protecting against the threat of explosion

Countering and protecting against the effects of explosions has utility beyond the defence and security spheres with technological advances finding civilian applications, as defence features writer Mark Lane discovers talking to Steve Holland of SJH Projects.

SJH Projects is a company which operates at the interface of defence and commercial technology in the field of blast and explosives.

The business, which is based in Nottinghamshire, was set up by Steve Holland in 2002. At one time he worked for BAE Space Systems, working on satellites and advanced materials before joining a composites company in the East Midlands.

Holland explains: “At that time, post-Lockerbie, there were a couple of projects which came out. One was for hardening narrow-bodied aircraft and one was for producing blast-resistant baggage containers – I ended up managing that project and that got me into countering the effects of blast with novel materials. Through a number of iterations that’s what I’ve been doing since.”

SJH provides a mixture of products, consultancy and testing. For its products it uses a material called XPT, which is an adaptation of a material used in industry.

“We’ve taken it and tuned it and made it more for our purposes,” he says. “It’s a bit like a stony sponge; it’s actually porous and the shock front from an explosion can enter it and the blast energy is then put to work in mechanically destroying it. It’s like a maze where the shockwave has to squeeze its way through, so when it comes out it’s not a nice neat shockwave, it’s very modified and easy to counter and energy is expended in destroying the material.

“It’s a sacrificial material. You could say it’s doing the same as a big block of foam but it does it in a much thinner cross-section, it’s much more robust and you can shape it and mould it.”

SJH has a range of products, including mailsafes for the containment of suspect mail; scansafes; and containers for explosive samples and detonators. Customers include governments and the private sector – “organisations that people might get annoyed with,” notes Holland.

The company produces variants for specialist laboratories as well as its K9-Safe units, which are designed to provide physical security, fire protection and blast containment for the explosive samples used when working with sniffer dogs. They are designed to be bolted onto the floor of the K9 unit’s vehicle. These are currently supplied to a European police force.

“When you are working with search dogs, whether in drugs or whatever, they generally have to know what they are looking for and you generally have to have some of the live substance, which means travelling around in your vehicles with small samples of live explosives,” he explains. “The police force inspectorate decided they ought to be doing this in a safer way so we produced a bespoke solution for them which is now available to others.”

The company also provides detonator containers which are used by militaries throughout the world. Detonators are sensitive to heat, vibration or shock and are therefore subject to a series of restrictions on their transportation and movement under the UN classification system.

“Logistically, it’s a major pain,” says Holland. “With our family of units, it allows you to move them at a much lower classification, which frees you up logistically.”

These are primarily supplied to the military, humanitarian de-mining organisations and police forces.

XPT is most appropriate for containment to counter localised intense blasts and it can also be used in the wheel arches of military vehicles to give protection against mines.

“It has gone into that field and has been used and deployed operationally,” says Holland.

SJH Projects has also become the key distributor for a range of artificial human parts produced by Adelaide T&E Systems of Australia.

These parts are used for testing the benefits of protective measures for events such as blast and ballistics. As well as overcoming ethical issues around the availability of human or animal parts, these surrogate systems provide repeatability, making interpretation of results more reliable.

The FSL or Frangible Surrogate Leg, for example, is designed to mimic the behaviour of a human leg under the rapid loading experienced when a person steps on an anti-personnel landmine or is in a vehicle hit by an improvised explosive device, or IED.

It has artificial bones that break at the same levels and in the same way as human bones. By taking measurements of the forces experienced, it can provide valuable information to both clinicians and engineers to develop systems to protect the lower limbs for both mounted and dismounted personnel in areas where there could be landmines and buried IEDs.

SJH is also building on this technology to develop its Frangible Surrogate Headform (FSH) in a remarkable example of technology transfer.

The FSH was also developed in Australia, for a TV programme on the assassination of US President John F Kennedy, to mimic the results of the impact of a bullet on a human skull.

Holland says: “What we wanted to do was to say: ’If we instrument this to put needle pressure gauges into the brain, could we reliably measure the sort of shockwave across the brain from an impact?’ We did that with a police force with some helmets.”

Sufficient impact on a composite helmet will cause it to touch the skull and transmit a shockwave. SJH compared the results of the tests using the FSH to published results of tests using cadaver skulls and found that they correlated.

SJH now wants to take its research further to measure how the brain moves around within the skull.

“In the military field body armour has got bigger over the last few years and it protects the thorax very well from blast, so people who would have died from blast injuries to the chest and abdomen in the past now aren’t, but pressure effects to the brain are showing up – mild traumatic brain injury where the brain gets shuddered within the skull,” explains Holland.

SJH wants to develop FSH so that it can become a tool to allow the better comparison of potential protective measures and new designs of helmet.

“In the same way that the frangible legs are an official NATO tool for comparing landmine boots, something is needed for comparing head protection,” he says. “We know how we would do it, but it’s a question of funding.”

Interestingly, the trials indicated that the British military helmet arrangement, whereby the helmet sits on a fabric harness which stops it from contacting the head, could provide better protection than the US model of attaching foam pads to the helmet.

“What we found was that if you hit the helmet and there’s a foam pad behind it, the foam pad compresses and does a very good job of transferring that shockwave through to your head,” says Holland. “But, it’s only through getting these measurements that you can prove the point.”

There is also a growing awareness of mild traumatic brain injury in sports.

“For sports like hockey or American football where there are helmets, it’s a way of making sure these helmets are actually doing the job and saying this one is better than that, because we’ve measured it, rather than saying because it looks sexy,” he says.

“There’s more technology transfer from the military sphere into the civil, whether it’s sport or protective helmets for whatever reason,’’ he adds. “It’s a niche market, but the need is quite important.”

Image: © SJH

 

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