Steels high-strength, commercial aircraft

Innovations in Materials. Carbon nanotubes have been heralded as a future super-material with strength hundreds of times that of steel for the same mass. As of the first decade of the twenty-first century, the longest strands of carbon nanotubes developed are still on the order of a few centimeters. This is a very impressive length-to-diameter ratio. Composite materials incorporating carbon already find wide use in various applications where high temperatures must be encountered. Metal matrix composites find use in primary structures even for commercial aircraft. Several smart structures have been developed, where sensors and actuators are incorporated into a material that has special properties to respond to stress and strain. These enable structures that will twist in a desired direction when bent or become stiffer or more flexible as desired, depending on... 

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