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The recently developed distinct element method for mesoscale modeling of carbon nanotubes is extended to account for energy dissipation and then applied to characterize the constitutive behavior of crystalline carbon nanotube bundles subjected to simple tension and to simple shear loadings. It is shown that if these structures are sufficiently long and thick, then they become representative volume elements. The predicted initial stiffness and strength of the representative volumes are in agreement with reported experimental data. The simulations demonstrate that energy dissipation plays a central role in the mechanical response and deformation kinematics of carbon nanotube bundles.

Abstract

The geometry and internal packing of twisted ropes composed of carbon nanotubes (CNTs) are considered, and a numerical solution in the context of the mesoscopic distinct element method (MDEM) is proposed. Compared to the state of the art, MDEM accounts in a computationally tractable manner for both the deformation of the fiber and the distributed van der Waals cohesive energy between fibers. These features enable us to investigate the torsional response in a new regime where the twisted rope develops packing rearrangements and aspect-ratio-dependent geometric nonlinearities. MDEM emerges as a robust simulation method for studying twisted agglomerates comprising semiflexible nanofibers.

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