“We strongly believe that integration of models and nondestructive evaluation, combined with multimaterial joints, will take automotive composites to the next level,” says Haq.
Morphing Wings Take Flight
Project: Cellular Composite Morphing Aircraft Wings
School: Massachusetts Institute of Technology (MIT)
Location: Cambridge, Mass.
Principal Investigator: Neil Gershenfeld
Researchers at the Massachusetts Institute of Technology (MIT) and NASA are experimenting with bendable, morphing aircraft wings that are built like a giant Lego® set – one cellular composite building block at a time.
Building lattice wing structures with tiny modular pieces – or “digital composites” – provides many advantages, including significant weight savings, increased flight control and the ability to utilize novel manufacturing techniques, according to Benjamin Jenett, graduate researcher at MIT’s Center for Bits and Atoms (CBA) and a NASA fellow. NASA’s Ames Research Center leads the project and partners with CBA, headed by Director Neil Gershenfeld. One of NASA’s investigators, Kenny Cheung, began the body of research at CBA as a graduate student.
The first version of the morphing wing, the Mission Adaptive Digital Composite Aero Structure Technologies (MADCAT) V0, was built from 100, interlocking, diamond-shaped pieces of six different designs, each less than three square inches. The parts were cut using a waterjet machine from 2 x 4-foot quasi-isotropic, CFRP sheets. A pneumatic drill mounted to the waterjet head pre-pierced the sheets to prevent delamination.
The parts were then hand-assembled into the lattice wing structure, with each interlocking piece affixed to another using a snap fit mechanical joint system and zip ties. Discrete pieces of 0.13-millimeter thick Kapton® polyimide film were laser cut into strips and used to create a non-structural skin with overlapping pieces resembling fish scales that slide over each other as the wing morphs. A full-span wing was tested in both MIT’s 8-foot Wright Brothers wind tunnel and NASA Langley Research Center’s 12-foot wind tunnel. Then a small, radio-controlled motor and propeller were added to complete the aircraft, which was tested at NASA’s Crow’s Landing flight facility.
The test wing structure provides an incredible stiffness-to-weight ratio, says Jenett. He notes that although cellular solids are a well-researched area of materials science and that there is “nothing magical about the geometry itself,” the ultra-lightweight, ultra-performance of these cellular solids had previously only been demonstrated in extremely small, millimeter-sized applications like aerogel materials. By using discrete lattice assembly, the approach can be scaled up to the size of an airplane.