Architected lattice structures made from pyrolytic carbon exhibit excellent characteristics as engineering materials. Strong, lightweight and low density, they can absorb a substantial amount of energy. A major factor holding these structures back from practical applications, however, is their scalability: although they perform well at sub-millimetre length scales, their strength has been found to drop as their dimensions increase.

The traditional way to make bigger lattice units would be to 3D print and pyrolyse larger structures — but at the cost of reducing their strength. Instead, the researchers’ new approach links multiple small lattice blocks through designed joints. Three possible joint mechanisms were tested: an ‘adhesive’ joint that bonds lattice units through aerospace-grade adhesive; a ‘Lego-adhesive’ joint that uses hole-and-cylinder connectors fortified with adhesive; and a ‘mechanical self-interlocking’ joint that uses no adhesive, only a hole-and-bolt-style connector. In this last mechanism, the bolts expand once pressed into the holes, securing the junctions.