Effects of temperature, strain rate, and vacancies on tensile and fatigue behaviors of silicon-based nanotubes

Abstract

This paper adopts the Tersoff-Brenner many-body potential function to perform molecular dynamics simulations of the tensile and fatigue behaviors of hypothetical silicon-based tubular nanostructures at various temperatures, strain rates, and vacancy percentages. The tensile test results indicate that with a predicted Young's modulus of approximately $60\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, silicon nanotubes $(\mathrm{SiNTs})$ are significantly less stiff than conventional carbon nanotubes. It is observed that the presence of hydrogen has a significant influence on the tensile strength of $\mathrm{SiNTs}$. Additionally, the present results indicate that the tensile strength clearly decreases with increasing temperature and with decreasing strain rate. Moreover, it is shown that the majority of the mechanical properties considered in the present study decrease with an increasing vacancy percentage. Regarding the fatigue tests, this study uses a standard theoretical model to derive curves of amplitude stress versus number of cycles for the current nanotubes. The results demonstrate that the fatigue limit of $\mathrm{SiNTs}$ increases with a decreasing vacancy percentage and with increasing temperature.