Size effects of mechanical properties of nanohoneycomb with multiple surface orientations

Abstract

Nanostructures and nanomaterials have been studied thoroughly due to their remarkable properties. With various sizes and shapes, they serve as highly functional sensors in nanoelectromechanical systems (NEMS), noninvasive medical diagnostic devices or drug delivers. Although the importance of surfaces has been recognized when it comes to the nanoscale, few researchers investigate nanostructures with multiple surface orientations. In this work, we propose a two-surface theoretical model for nanohoneycombs and verify the model by conducting molecular dynamics (MD) simulations on regular hexagonal Al nanohoneycombs with cell-wall thickness ranging from 5 nm to 30 nm. These numerical examples show excellent agreement with the proposed theory, proving the applicability of the two-surface model. The Al nanohoneycomb exhibits significant “positive” size dependence – it is 2.4 times stiffer compared with its large counterpart when the cell-wall thickness is 5.7 nm. In sum, this study improves the accuracy of the predicted in-plane Young's moduli of nanohoneycombs by taking differently oriented surfaces into account and considering more comprehensive deformation mechanisms. By investigating nanosized honeycomb structure in-depth and providing a more general theoretical model, we aim to improve the accuracy of predicted mechanical properties and provide a guide for the applicability of various models for honeycombs. Furthermore, this study can help exploit the full potential of various nanoporous structures, not restricted to nanohoneycombs.