In collaboration with researchers from the University of Minnesota (US), Igor Ostanin, a postdoc from Skoltech CREI on Computational and Data Intensive Science and Engineering (Scientific Computing group), , has published a paper in the American Chemical Society Journal “Langmuir”. This article got on the cover of “Langmuir” (issue from November 17, 2015). The paper is about Carbon Nanotubes (CNTs).
In this work researchers suggest an efficient method of modeling CNT systems, based on distinct element method. Their new technique allows modeling very large CNT systems without compromising the accuracy. An essential feature of this method is a very accurate representation of van der Waals interactions between CNTs. They studied the stiffness of a twisted CNT fiber and changes in packing of twisted CNT bundles and identified corresponding regimes of mechanical response. Besides that, they investigated the regimes when the response is dominated by the elastic instability, when the stored twisted energy is partly transformed into bending during fiber takes a spiral shape. All these results are of considerable interest for an interpretation of experiments with CNT ropes and bundles. Also in a number of cases predictive in silico experiments can be a reasonable substitute for expensive experimental investigations.
Carbon Nanotubes and CNT-based materials remain an important research topic in modern materials science. CNTs possess Young’s modulus (a mechanical property of linear elastic solid materials) six times greater than steel and yield strength that is three orders of magnitude higher that of steel. Such a high strength is due to absence of any crystalline defects – the strength of a CNT is defined only by the strength of carbon covalent bond.” Unfortunately, modern synthesis technologies do not allow growing CNT arrays of an arbitrary length. This has motivated the research aimed at synthesis of ropes made out of bundles of CNTs. The basic idea – known to humankind from pre-historic era – a twisted rope provides high tensile strength, because twisted fibers are pushed toward each other, and frictional force, proportional to the tensile load, prevents these fibers from gliding. But this approach is generally inefficient for CNTs, since sliding of their smooth and chemically reactive interfaces do not obey the laws of dry friction”, – told Igor Ostanin. New experimental research in this area suggests that synthesis of hierarchically spun and chemically linked ropes of CNTs is a perspective research direction. Besides, such configurations of CNTs have been recently used in artificial muscles, which is extremely hot topic of the applied research in this area.
In order to develop an efficient design of CNT ropes, one needs numerical modeling tools that would give clear understanding of loading mechanisms, behavior of packing defects and nonlinear deformation modes of CNT ropes. Molecular dynamic simulations that are often used to study mechanical properties of a single CNT are too expensive for the problems of modeling of thousands of CNTs and hundreds of millions carbon atoms. This work actually offers such tools.
http://pubs.acs.org/doi/abs/10.1021/acs.langmuir.5b03208
* The Skolkovo Institute of Science and Technology (Skoltech) is a private graduate research university in Skolkovo, Russia, a suburb of Moscow. Established in 2011 in collaboration with MIT, Skoltech educates global leaders in innovation, advances scientific knowledge, and fosters new technologies to address critical issues facing Russia and the world. Applying international research and educational models, the university integrates the best Russian scientific traditions with twenty-first century entrepreneurship and innovation.
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