These Carbon Composites Shape-Shift in Response to Environmental Triggers

Researchers at MIT are developing various shape-shifting materials, including carbon fiber composites, wood grains and textiles, that could lead to self-assembling structures or more efficient cars and planes. The materials shift between two or more shapes in response to changes in heat, air pressure, or other environmental factors. Shape-shifting materials are not new, but their use has been limited in aerospace because most materials can’t handle the conditions planes are exposed to. Carbon composites, however, can be integrated into aircraft easily and replace the need for more complex hydraulic actuators, motors and hinges. Airbus is working with MIT to apply these materials to airplanes, such as a jet engine’s air intake valve, which needs to adjust as the plane changes altitude. In addition, supercar manufacturer Briggs Automotive Company is looking to the shifting carbon fibers for aerodynamics, working on the first non-mechanical morphing car airfoil. Unlike other shape-shifting materials, MIT’s shifting carbon composites can be paired with different shape-changing materials that respond to different environmental triggers. This allows the engineers to choose a specific trigger that won’t be accidentally set off in the wrong conditions. Skylar Tibbits, director of Self-Assembly Lab and research scientist at MIT, says making the process first involves using novel carbon fiber composites developed by Carbitex, which use a variety of matrix materials that impart a range of properties. Some of their carbon composites are floppy; others are springy. Then a 3-D printer applies materials that are known to shrink or grow under certain conditions. As they change, they force the carbon composite on which they’re deposited to bend or twist in various ways, depending on the pattern produced by the printer. So far, Tibbits has demonstrated materials that respond to light, water and heat, but hopes to make more that respond to air pressure and other stimuli. Down the line, the materials could even be used for packages that self-assemble in space into a complete satellite.