'Nanostitching' could make airplanes 10 times stronger

Washington, March 5 (ANI): The future of flight seems safe, with engineers at MIT 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, according to Brian L. Wardle, from the Department of Aeronautics and Astronautics, MIT.

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 develop processing techniques for creating the nanotubes and for incorporating them into existing aerospace composites.

As to how nanostitching works, the research team said that the polymer glue between two carbon-fiber layers is heated, becoming more liquid-like.

Billions of nanotubes positioned perpendicular to each carbon-fiber layer are then sucked up into the glue on both sides of each layer.

Because the nanotubes are 1000 times smaller than the carbon fibers, they don't detrimentally affect the much larger carbon fibers, but instead fill the spaces around them, stitching the layers together.

"So, we're putting the strongest fibers known to humankind (the nanotubes) in the place where the composite is weakest, and where they're needed most," Wardle said. (ANI)