Finding the right balance between protection and mobility is a life or death issue for the military. A soldier whose mobility is compromised by heavy loads cannot respond quickly to threats, but troops with minimal protection are extremely vulnerable to attack.
Body armour offers more potential for weight reduction than firearms, ammunition or telecoms, but, historically, the only way to establish the effectiveness of a material has been ballistic testing, where a prototype is tested to destruction by firing bullets at it.
This is expensive, time-consuming and a real barrier to progress. However, a research and development project that uses a powerful X-ray scanning technology to analyse materials and simulate impacts could offer a time, money and possibly life-saving shortcut.
Scanning for a better method
In the four years since it was installed, the high-resolution computer tomography (CT) scanner at the Warwick Manufacturing Group (WMG) – part of the High Value Manufacturing Catapult established by Innovate UK – has been used by over 100 companies to analyse materials.
It enables both a material’s characteristics (like porosity or density) and its behaviours when affected by conditions like tensile stress or compression, to be analysed.
“The imaging and X-ray facilities at WMG offer a non-destructive, non-invasive way to analyse and characterise materials. This means fewer experimental tests are required and reduces both the costs and duration of testing” Professor Mark Williams, Product Evaluation Technologies Research Group Leader at WMG, explained.
The resolution of the Micro CT scanner at WMG is particularly impressive. A normal medical X-ray scanner will scan to 600 microns, one six-hundredth of a millimetre. “We can get to over 100 times that, sub-six microns, with our machine,” he added.
Advancing armour testing
For project partners Simpact Engineering and Morgan Advanced Materials, who are researching scanning and simulation technologies as an alternative to ballistic testing of body and vehicle armour, the WMG centre and the Micro CT scanner are indispensable.
Their initial research began at WMG’s Premium Vehicles Customer Interface Technologies (PVCIT) centre – a £10m simulation technology research programme.
“We want body and vehicle armour testing to reach the same level of maturity as the automotive industry where you only need physical confirmation tests at the very end of development, reducing both the costs and length of the process,” says Dr. Dirk Landheer of Simpact.
Using CT scanning techniques has helped the partners improve correlation between mathematical models and the results of experimental testing, enabling them to simulate ballistic testing with a much higher degree of confidence. It also offers benefits when evaluating materials before and after ballistic testing as well.
WMG has given us a clear advantage. It's enabled us to take computer-aided engineering and testing of body and vehicle armour to unprecedented levels. This step forward may not just save time and money, it could save lives
Dr. Dirk Landheer of Simpact
In ballistic testing samples are measured beforehand to confirm their shape, size and density. After impact the damaged or broken sample is visually inspected and re-measured, but the data provided is limited.
Scanning samples before testing reveals far more information about them; for example, how well the backing material (that dissipates the kinetic energy of the projectile) is bonded to the ceramic face. Post-test, it enables more accurate measurement both of the fragments and the damage to the backing material.
“The Micro CT scanner was instrumental in helping us gain insight into imperfections in engineered ceramics and in quantifying damage to armour after ballistic testing,” Dirk added.
“The insights provided by CT scanning help us to better understand the interactions between the various constituents of our armour and will ultimately lead to improved, lighter weight solutions,” says Stuart Bailey of Morgan Advanced Materials.
Applications and the future
Simpact is close to perfecting several design aspects of body armour and is working with Morgan Advanced Materials and its high-strength fibre composite suppliers in close collaboration with the military.
The companies expect to deliver a next generation lighter, battlefield-ready product by 2017. However, the first computer-model driven improvements to existing products could be available as early as spring 2015.
CT material characterisation also has huge cross-sector potential, says Professor Williams, who is evangelical about the technology.
“It’s got uses anywhere where you want to avoid damage in testing – heritage, aerospace, aluminium bonding for the car industry; specifically Jaguar Land Rover’s new Land Rover bodies. Forensics is also becoming popular,” he added.An exciting field for the near future is greater use of 3D visualisation combined with the CT simulation, coupled with a new, more powerful scanner. “Feeding high levels of material characterisation data into 3D visual software creates a very powerful analysis,” Mark adds.
After the success of their research, Simpact and Morgan Advanced Materials are also enthusiastic advocates.