Toward large scale modeling of carbon nanotube systems with the mesoscopic distinct element method

Abstract

A new scalable and efficient implementation of the mesoscopic distinct element method for massively parallel numerical simulations of carbon nanotube systems is introduced. Carbon nanotubes are represented as chains of rigid bodies, linked by elastic bonds and dispersive van der Waals (vdW) forces. The enhanced vector model formalism of the elastic bond between rigid bodies, developed recently, is employed here to capture the elastic deformation of nanotubes. Dispersive interactions between the neighboring nanotubes are described with the coarse-grained vdW potential. Time integration is performed using a velocity Verlet integration scheme with tunable damping in order to describe the energy dissipation to the implicit degrees of freedom. Due to the scalable message passing interface (MPI) parallelization, enabled by rigid particle dynamics module (PE) of the waLBerla multiphysics framework, our method is capable of modeling large assemblies of carbon nanotubes. This advance enables us to move closer to the length and time scales required to extract representative mechanics of carbon nanotube materials. The promising scalability of the new implementation is probed in two examples of self-assembly of ultrathin carbon nanotube films and carbon nanotube buckypapers, where formation of hierarchical networks of carbon nanotube bundles, storing both elastic and vdW adhesion energies is observed. The relaxation of one cubic micrometer of buckypaper illustrates the code scalability.

Densification of single-walled carbon nanotube films: Mesoscopic distinct element method simulations and experimental validation

“…The key components (for the present investigation) of the two-body EVM potential U ij describe the resistance to stretching U t ij and bending U b ij deformation of the two elements, Fig. 1(b) right, as34,37…”

Distinct Element Simulation of Mechanical Properties of Hypothetical CNT Nanofabrics

“…The most important of them is absent torsional stiffness of fibrils leading to unrealistic behaviors of fibrillar assemblies under certain loadings. In order to solve this issue, a different discretization concept [12][13][14][15][16][17][18][19] was suggested using a representation of a thin fiber as a chain of rigid bodies, rather than point masses. Such a model allows not only bending of individual fibers, but their torsion as well.…”

“…Until now, the remaining obstacle on the route toward applications of MDEM to large-scale modeling of fibrillar assemblies was the absence of its scalable, parallel realization. Such realization has been recently suggested in [19]. It is based on rigid particle dynamics module of the waLBerla multiphysics framework [20].…”

High-Performance Numerical Modeling of Nanofabrics with Distinct Element Method

“…The most important of them is absent torsional stiffness of fibrils leading to unrealistic behaviors of fibrillar assemblies under certain loadings. In order to solve this issue, a different discretization concept [12,13,14,15,16,17,18,19] was suggested using a representation of a thin fiber as a chain of rigid bodies, rather than point masses. Such a model allows not only bending of individual fibers, but their torsion as well.…”

“…Until now, the remaining obstacle on the route toward applications of MDEM to large-scale modeling of fibrillar assemblies was the absence of its scalable, parallel realization. Such realization was recently suggested in [19]. It is based on rigid particle dynamics module of the waLBerla multiphysics framework [20].…”