Effect of Geometrical Parameters and Hexa-Vacancy Defects on Vibration Characteristics of Bridged Carbon Nanotube
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TECHNICAL ARTICLE—PEER-REVIEWED
Effect of Geometrical Parameters and Hexa-Vacancy Defects on Vibration Characteristics of Bridged Carbon Nanotube Mohit Goel . S. P. Harsha . M. P. Mishra . R. K. Mishra
Submitted: 28 July 2020 / Accepted: 1 September 2020 ASM International 2020
Abstract Carbon nanotubes with bridged boundary conditions are widely used in the design of nano-sensors and oscillators. However, defects are inseparable from the carbon nanotubes which can affect its dynamics behavior and sensing performance. Influence of hexa-vacancy defect in terms of their numbers and migration along the length of the bridged single-walled carbon nanotube (SWCNT) is investigated through MD simulations. Moreover, effects of geometric parameters like length, diameter and chirality are studied for pristine SWCNT under bridged boundary condition. Effects of these aspects on free vibration response of SWCNT are studied through change in principal natural frequencies. It is observed that effect on the natural frequency get enhanced with increase in numbers of vacancy defect. Vibration characteristics of bridged SWCNT are less affected by the vacancy defect placed at mid-portion of the tube length. It is also found that shorter and thicker SWCNT offer higher vibrational sensitivity. Effect of chirality becomes less pronounced for longer tubes. The results of this study provide valuable input in the design of SWCNT-based nano-sensors.
M. Goel M. P. Mishra Instruments Research & Development Establishment, Dehradun, India M. Goel S. P. Harsha Vibration & Noise Control Laboratory, Mechanical & Industrial Engineering Department, Indian Institute of Technology Roorkee, Roorkee, India R. K. Mishra (&) Regional Centre for Military Airworthiness, Bangalore, India e-mail: [email protected]
Keywords Molecular dynamics Natural vibration Single-walled carbon nanotube Chirality Vacancy defect
Introduction Vibration characteristics of carbon nanotubes (CNT) find their application in numerous nano-devices like resonators, oscillators, vibration sensors, charge detectors and field emission devices [1–4]. The vibration phenomena are also used for the design of the nano-balances which measure masses in the range of pictogram to femto-gram [5–7]. High stiffness, strength and large surface area with small size of single-walled carbon nanotube (SWCNT) make them to respond quickly to the external mechanical deformation with high sensitivity. Vibration of CNT under both cantilever and bridged configuration is utilized to design the nano-electromechanical systems (NEMS). In applications, like nano-oscillators and nano-strain sensors, the CNT sensor is generally clamped at both ends [8–11]. It was reported that the fundamental frequencies of cantilevered or bridged single-walled carbon nanotubes could reach the level of 10 GHz to 1.5 THz depending upon the diameter and length of nanotube [7–9]. Vibrational behavior of CNTs and their composites have been studied by many researchers [12–15]. Beside experiments, which are challeng
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