A considered application of carbon nanotubes is nanopiping in nanofluidic devices. The use of nanotubes for fluid transport requires large-diameter tubes that can sustain prescribed loading without failure. Two models of the stress-strain state of long multiwall carbon nanotubes, subjected to internal pressure, are described. Cylindrical nanotubes having a Russian doll structure have been considered. It is assumed that the deformations are linear elastic and negligible along the tube axis (in comparison with the radial deformations). This assumption is not restrictive for potential applications of nanotubes, where their deformations must he small and reversible. The distance between the layers is small in comparison to the radii of curvature of graphite layers. In the case of several carbon layers, a discrete model (DM) is proposed. The solutions of DM equations, with corresponding boundary conditions, determine the stresses between the layers, the forces in the layers, and the deformation of the layers. For the case of thick walls built of numerous carbon layers, a continuous model (CM) is proposed. The main CM equation is the Euler's differential equation with corresponding boundary conditions. Its solution defines the continuous distribution of the stresses and strains across the wall thickness of the tube.
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