To save on fuel and reduce aircraft emissions, engineers are looking to build lighter, stronger airplanes out of advanced composites. These engineered materials are made from high-performance fibers that are embedded in polymer sheets. The sheets can be stacked and pressed into one multilayered material and made into extremely lightweight and durable structures.
But composite materials have one main vulnerability: the space between layers, which is typically filled with polymer "glue" to bond the layers together. In the event of an impact or strike, cracks can easily spread between layers and weaken the material, even though there may be no visible damage to the layers themselves. Over time, as these hidden cracks spread between layers, the composite could suddenly crumble without warning.
Now, MIT engineers have shown they can prevent cracks from spreading between composite's layers, using an approach they developed called "nanostitching," in which they deposit chemically grown microscopic forests of carbon nanotubes between composite layers. The tiny, densely packed fibers grip and hold the layers together, like ultrastrong Velcro, preventing the layers from peeling or shearing apart.
In experiments with an advanced composite known as thin-ply carbon fiber laminate, the team demonstrated that layers bonded with nanostitching improved the material's resistance to cracks by up to 60 percent, compared with composites with conventional polymers. The researchers say the results help to address the main vulnerability in advanced composites.
Was wondering when they were going to around to doing that.
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