Atomistic simulations on the influence of diameter, number of walls, interlayer distance and temperature on the mechanical properties of BNNTs

The molecular dynamics (MD) simulation is used to calculate the mechanical properties of single, double and triple walled BNNTs (SWBNNT, DWBNNT and TWBNNT). The effects of diameter, chirality, interlayer distance and temperature on the mechanical properties of respected systems have been investigated. The results showed that, zigzag BNNTs are stiffer than armchair ones with nearly the same diameter. Also the Young's modulus of both type of SWBNNTs increase when the tube diameter increases till the specific diameter and then decrease slightly. We found that diameter changes have no significant influence on the failure stress and strain of zigzag BNNTs. In addition, the results confirmed that all measured mechanical properties decrease with increasing temperature. Furthermore, the Young's modulus of DWBNNTs are smaller than TWBNNTs and larger than SWBNNT. We showed that the Young's modulus of DWCNTs with various interlayer distances increase when separation wall distances were decreased. Our simulation findings afford not only a molecular level understanding of the BNNTs but also may be instructive to mechanical engineers and scientists who attempt to develop effective mechanical properties. (C) 2015 Elsevier Ltd. All rights reserved.