NASA and MIT researchers have designed a new ultra-light bendable 'morphing wing' that could greatly simplify the manufacturing process and reduce fuel consumption by improving aerodynamics.
The basic principle behind the new concept is the use of an array of tiny, lightweight structural pieces, which researchers call 'digital materials', that can be assembled into a virtually infinite variety of shapes, much like assembling a structure from Lego blocks. The assembly could be done by simple miniature robots that would crawl along or inside the structure as it took shape. The team has already developed prototypes of such robots.
The individual pieces are strong and stiff, but the exact choice of the dimensions and materials used for the pieces, and the geometry of how they are assembled, gives a precise tuning of the flexibility of the final shape. For the initial test structure, the goal was to allow the wing to twist in a precise way that would substitute for the motion of separate structural pieces (such as the small ailerons at the trailing edges of conventional wings) while providing a single, smooth aerodynamic surface.
Building up a large and complex structure from an array of small, identical building blocks, which have an exceptional combination of strength, light weight and flexibility, simplifies the manufacturing process, said Neil Gershenfeld from Massachusetts Institute of Technology (MIT) in the US. While the construction of light composite wings for today's aircraft requires large, specialised equipment for layering and hardening the material, the new modular structures could be rapidly manufactured in mass quantities and then assembled robotically in place.
This research, "presents a general strategy for increasing the performance of highly compliant that is, 'soft' robots and mechanisms," said Kenneth Cheung researcher at NASA. By replacing conventional flexible materials with new cellular materials "that are much lower weight, more tunable, and can be made to dissipate energy at much lower rates" while having equivalent stiffness, said Cheung.
The 'skin' of the wing also enhances the structure's performance. It is made from overlapping strips of flexible material, layered somewhat like feathers or fish scales, allowing for the pieces to move to each other as the wing flexes, while still providing a smooth outer surface.
One of this system's big advantages is that when it is no longer needed, the whole structure can be taken apart into its component parts, which can then be reassembled into something completely different and repairs could be made by simply replacing an area of damaged subunits, Gershenfeld said.
"An inspection robot could just find where the broken part is and replace it, and keep the aircraft 100 percent healthy at all times," said Benjamin Jenett from MIT.
