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The material could lead to the development of safer, lighter and more durable structures for use in the aerospace, automotive, renewable energy and marine sectors, the researchers said.
The team, led by University of Glasgow engineers, developed a new ‘plate-lattice cellular metamaterial’ capable of impressive resistance to impacts.
Metamaterials are a class of artificially created cellular solids, designed and engineered to have properties which do not occur in the natural world. One form of metamaterials, known as plate-lattices, are cubic structures made from intersecting layers of plates that exhibit unusually high stiffness and strength, despite featuring a significant amount of space between the plates. That porosity also makes plate-lattices unusually lightweight.
The researchers set out to investigate whether new forms of plate-lattice design, manufactured from a plastic-nanotube composite they developed, could make a metamaterial with even more advanced stiffness, strength and toughness.
The composite includes a mixture of polypropylene or polyethylene – low-cost, reuseable plastics widely used in everyday items like bags and bottles – and multi-wall carbon nanotubes.
The team used its nanoengineered filament composite as the feedstock in a 3D printer, which fused the filaments together to build a series of plate-lattice designs. Those designs were then subjected to a series of impact tests by dropping a 16.7kg mass from a range of heights to determine their ability to withstand physical shocks.
A ‘hybrid’ plate-lattice design, including multi-faceted aspects, proved to be the most effective in absorbing impacts. The polypropylene version showed the greatest impact resistance. The team found that it could withstand 19.9 joules per gram – a superior performance over similarly-designed micro-architected aluminium metamaterials.
Dr Shanmugam Kumar, reader in composites and additive manufacturing in the James Watt School of Engineering, led the research project. The research team also involved mechanical and chemical engineers from Khalifa University in Abu Dhabi and Texas A&M University.
Dr Kumar said: “This work sits right at the intersection of mechanics and materials. The balance between the carbon nanostructure-engineered filaments we’ve developed as a feedstock for 3D printing, and the hybrid composite plate-lattice designs we’ve created, has produced a really exciting result.
“In the pursuit of lightweight engineering, there is a constant hunt for ultra-lightweight materials featuring high performance. Our nano-engineered hybrid plate-lattices achieve extraordinary stiffness and strength properties and exhibit superior energy absorption characteristics over similar lattices built with aluminium.”
He added: “Advances in 3D printing are making it easier and cheaper than ever to fabricate the kinds of complicated geometries with tailored porosity that underpin our plate-lattice design. Manufacture of this kind of design at industrial scales is becoming a real possibility.
“One application for this new kind of plate-lattice might be in automobile manufacture, where designers perpetually strive to build more lightweight bodies without sacrificing safety during crashes. Aluminium is used in many modern car designs, but our plate-lattice offers greater impact resistance, which could make it useful in those kinds of applications in the future.
“The recyclability of the plastics we’re using in these plate-lattices also makes them attractive as we move towards a ‘net-zero’ world, where circular economic models will be central to making the planet more sustainable.”
The team’s paper, titled ‘Impact behaviour of nanoengineered, 3D-printed plate-lattices’, was published in Materials & Design. The work was supported by funding from the Abu Dhabi National Oil Company and the University of Glasgow.
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