Effect of vacancy defect on natural vibrations of a single walled …

In this paper, the effect of vacancy defect on natural vibrations of single walled carbon nanotubes (SWCNTs) is investigated. Vacancy defect occurs during growth process therefore determining natural frequency of defected SWCNTs is very important for improving their sensing or actuating performance. Molecular dynamics and finite element methods have been employed to simulate SWCNTs. Related stiffness is calculated from molecular potential energy. Accuracy of modeling is determined by comparing our results of predicting ideal SWCNT natural frequency with the results from the previous studies. Two cases are studied. First, vacancies are scattered randomly on SWCNT structure for better simulation of actual condition, and effect of aspect ratio, vacancy ratio, and boundary conditions on natural vibration of defected SWCNTs is investigated. Second, single vacancy is considered and effect of aspect ratio, vacancy position and boundary conditions on natural vibration of defected SWCNTs is investigated. Zigzag carbon nanotubes with chirality indices (8, 0) and (10, 0) are studied in both cases. The results, in the first case, indicate that by increasing aspect ratio, the principal natural frequency shift decreases. This shift is affected by vacancy ratio. Distribution of vacancies affect natural frequency shift. As vacancies approach to the clamped end, natural frequency shift increases. In the second case, effect of aspect ratio, vacancy position, and boundary conditions is investigated.