▎ 摘　　要

In this paper, a new method has been proposed for determining mechanical properties of single-layer graphene sheets, without applying any external force and simply by measuring natural deformations of these sheets due to their ambient environmental conditions. Furthermore, the merits and potential applications of this method have been investigated by using Non-Equilibrium Molecular Dynamics (NEMD) virtual laboratory. Contrary to the ordinary methods of identifying mechanical systems, which rely on dynamic response of one structure to a predefined excitation, here the output-only frequency domain decomposition method has been employed. After presenting the theory behind the employed approaches, a virtual laboratory called the Laboratory of Nanometric Operational Modal Analysis (LNOMA) was set up and by using this laboratory, mechanical properties of single-layer graphene sheets were determined and compared with those obtained in previous works. Equivalent elastic modulus, Poisson's ratio and thickness of the examined graphene sheet were found to be 1.05 Tpa, 0.17 and 2.885 angstrom, respectively. For the higher order natural frequencies, the equivalent thickness varies as 1.941, 2.00133, 1.4575, 1.307 and 1.3335 angstrom for the 2nd to 6th mode shapes,respectively. An important point is that with the increase of the mode number, the equivalent thickness decreases, and after the 4th mode, the thickness ratio (equivalent thickness/frequency) does not change significantly and could be considered as 0.2 for the higher order modes. All the results obtained by applying random excitations; and this shows the importance of the present work for future experiments. (C) 2017 Elsevier Masson SAS. All rights reserved.