Troy, N.Y. -- The ability of carbon nanotubes to withstand repeated stress yet retain their structural and mechanical integrity is similar to the behavior of soft tissue, according to a new study from Rensselaer Polytechnic Institute.
When paired with the strong electrical conductivity of carbon nanotubes, this ability to endure wear and tear, or fatigue, suggests the materials could be used to create structures that mimic artificial muscles or interesting electro-mechanical systems, researchers said.
The report, Fatigue resistance of aligned carbon nanotube arrays under cyclic compression, appears in the July issue of Nature Nanotechnology. Despite extensive research over the past decade into the mechanical properties of carbon nanotube structures, this study is the first to explore and document their fatigue behavior, said co-author Victor Pushparaj, a senior research specialist in Rensselaers department of materials science and engineering.
The idea was to show how fatigue affects nanotube structures over the lifetime of a device that incorporates carbon nanotubes, Pushparaj said. Even when exposed to high levels of stress, the nanotubes held up extremely well. The behavior is reminiscent of the mechanics of soft tissues, such as a shoulder muscle or stomach wall, which expand and contract millions of times over a human lifetime.
Pushparaj and his team created a free-standing, macroscopic, two-millimeter square block of carbon nanotubes, made up of millions of individual, vertically aligned, multiwalled nanotubes. The researchers then compressed the block between two steels plates in a vice-like machine.
The team repeated this process more than 500,000 times, recording precisely how much force was required to compress the nanotube block down to about 25 percent of its original height.
Even after 500,000 compressions, the nanotube block retained its original shape and mechanical properties. Similarly,
Contact: Michael Mullaney
Rensselaer Polytechnic Institute