Buckling Behaviors of Imperfect Single-Walled Carbon Nanotubes: A Molecular Dynamic Simulation

Carbon nanotube has attracted tremendous scientific and industrial interests due to its exceptional mechanical, electrical and thermal properties. In this paper, classic molecular dynamic simulations are carried out to investigate the buckling behaviors and mechanical properties of single-walled carbon nanotubes under axial compression, both for perfect and imperfect ones introducing atomic vacancies. The effect of chirality, diameter, quantity and position of vacancy are systematically studied. The simulation results reveal that their mechanical properties such as Young’s modulus, critical strain and stress suffering a significant decline as the increasing numbers of vacancies. It is also found that the critical stress and strain are sensitive to position of atomic vacancy. Carbon nanotubes with vacancies located at the center have lower critical strain and are easier to reach the failure stage than those with vacancies at both sides.

Theoretical Study of Transport Parameters Inside Catalyst Layer of Polymer Electrolyte Fuel Cell

One of the key components inside fuel cell is the catalyst layer which has the most complex composition and transport phenomena. Physical parameters which often used in the simulation works regarding catalyst layer are mostly based on the empirical relations or derivation from experimental results. Transport parameters for species inside Nafion phase are critical for the catalyst layer modeling. This paper uses a nano-scale approach — classic molecular dynamic (CMD) simulation to evaluate the transport parameters inside Nafion phase of the catalyst layer. Two important transport parameters, oxygen diffusivity and water diffusivity, are evaluated at different conditions. The dependency of these two transport parameters on the various operation conditions such as different water content and temperature etc are also investigated. Simulation works at different scale (ex: CFD etc) can be easily improved by incorporating correlations obtained by the present work based on the CMD.