MIT researchers have developed a lightweight structure whose tiny blocks can be snapped together much like the bricks of a child’s construction toy. The new material, the researchers say, could revolutionize the assembly of airplanes, spacecraft, and even larger structures, such as dikes and levees.
The structure is made from tiny, identical, interlocking parts. The parts, based on a novel geometry, form a structure that is 10 times stiffer for a given weight than existing ultralight materials. But this new structure can also be disassembled and reassembled easily — such as to repair damage, or to recycle the parts into a different configuration. The individual parts can be mass-produced; a robotic system assembles them into wings, airplane fuselages, bridges or rockets.
With conventional composites — now used in everything from golf clubs and tennis rackets to the components of Boeing’s new 787 airplane — each piece is manufactured as a continuous unit. Therefore, manufacturing large structures, such as airplane wings, requires large factories where fibers and resins can be wound and parts heat-cured as a whole, minimizing the number of separate pieces that must be joined in final assembly. That requirement meant, for example, Boeing’s suppliers have had to build enormous facilities to make parts for the 787.
Pound for pound, the new technique allows much less material to carry a given load. This could not only reduce the weight of vehicles, for example — which could significantly lower fuel use and operating costs — but also reduce the costs of construction and assembly, while allowing greater design flexibility. The team is now developing an assembler robot that can crawl, insectlike, over the surface of a growing structure, adding pieces one by one to the existing structure.
In traditional composite manufacturing, the joints between large components tend to be where cracks and structural failures start. While these new structures are made by linking many small composite fiber loops, the researchers show that they behave like an elastic solid, with a stiffness, or modulus, equal to that of much heavier traditional structures — because forces are conveyed through the structures inside the pieces and distributed across the lattice structure.
The possibility of linking multiple types of parts introduces a new degree of design freedom into composite manufacturing. The researchers show that by combining different part types, they can make morphing structures with identical geometry but that bend in different ways in response to loads: Instead of moving only at fixed joints, the entire arm of a robot or wing of an airplane could change shape.