CAMBRIDGE, Mass.--MIT engineers are using carbon nanotubes only billionths of a meter thick to stitch together aerospace materials in work that could make airplane skins and other products some 10 times stronger at a nominal increase in cost.
Moreover, advanced composites reinforced with nanotubes are also more than one million times more electrically conductive than their counterparts without nanotubes, meaning aircraft built with such materials would have greater protection against damage from lightning, said Brian L. Wardle, the Charles Stark Draper Assistant Professor in the Department of Aeronautics and Astronautics.
Wardle is lead author of a theoretical paper on the new nanotube-reinforced composites that will appear in the Journal of Composite Materials (http://jcm.sagepub.com/). He also described the work as keynote speaker at a Society of Plastics Engineers conference this week.
The advanced materials currently used for many aerospace applications are composed of layers, or plies, of carbon fibers that in turn are held together with a polymer glue. But that glue can crack and otherwise result in the carbon-fiber plies coming apart. As a result, engineers have explored a variety of ways to reinforce the interface between the layers by stitching, braiding, weaving or pinning them together.
All of these processes, however, are problematic because the relatively large stitches or pins penetrate and damage the carbon-fiber plies themselves. "And those fiber plies are what make composites so strong," Wardle said.
So Wardle wondered whether it would make sense to reinforce the plies in advanced composites with nanotubes aligned perpendicular to the carbon-fiber plies. Using computer models of how such a material would fracture, "we convinced ourselves that reinforcing with nanotubes should work far better than all other approaches," Wardle said. His team went on to d
|Contact: Elizabeth Thomson|
Massachusetts Institute of Technology