Evaluating the Fracture Pattern in Defective DWCNT Using Molecular Structural Mechanics Approach

Abstract

Background: This manuscript deals with identifying the fracture pattern in defective Double Walled Carbon Nanotubes (DWCNT). It has been projected in a number of published papers that CNTs always possess defects like vacancies in their structure, hence this type of analysis is helpful in studying the pattern of fracture when subjected to tensile and other types of forces. Method: Molecular structural mechanics approach is used to model the defective DWCNT and finite element method is used to simulate the responses of the non-linear force field of the C–C bonds for analysing the systematic fracture in double walled carbon nanotube structure with beam elements. The model has been studied with reference to arm chair and zigzag DWCNTs with an atomic vacancy and exposed to critical tension. The defect presented here (model) is one lacking atom at the outer tube of the double walled carbon nanotube. Results: The failure pattern is found to be different in all the two types of DWCNTs mainly because of the orientation of the covalent bond between carbon - carbon atoms. This orientation further leads to the change in the stiffness of the bonds which further leads to increase in the stress at the junction and later on failure of the tube. The type of pattern evaluated in this manuscript has not been studied previously in DWCNTs. Conclusion: Catastrophic failure took place after fifteen consecutive iterations, for zigzag and armchair of DWCNT. It shows that Zigzag DWCNT ((14,0)@(8,0)) has better strength compared to Arm chair DWCNT ((8,8)@(6,6)). Keywords: DWCNT, finite element method, systematic fracture, molecular structural analysis, van der Waals, fracture pattern.