بررسی ارتعاشات آزاد طولی نانومیله‌های آلومینیومی یکسرگیردار با استفاده از شبیه‌سازی دینامیک مولکولی

The aim of this paper is to extract the natural axial frequencies of aluminum nanorods using molecular dynamics simulation. It is essential to note that a comparison between experimental results and classical theories (used at the macro scale) has shown that classical theories cannot accurately predict the behavior of nanostructures! The simulated nanorods have lengths of 6, 7, 8, 9, and 10 nanometers. Furthermore, for more detailed investigation, the cross-section of the nanorods is assumed to be square, with two values considered for their dimensions: 0.8 and 1.6 nanometers. The boundary condition under study is the cantilever boundary condition. To extract the natural frequencies, an initial excitation must be applied to the nanorod. This is achieved by applying a force to one end of the nanorod along its length, causing an initial displacement, and then releasing it, setting the nanorod into vibration. By recording the axial displacement of atoms located at the free end of the nanorod at different time steps, the recorded data can be analyzed in the frequency domain using the Fast Fourier Transform. The results of this research indicate that, although classical theories suggest that the frequencies of axial vibrations are independent of the cross-sectional area of the structure, the frequencies of nanorods at the nanoscale are dependent on the dimensions of their cross-section. The findings of this study can serve as a useful guide for researchers in the field of vibrations and as a reliable reference for the design of nano-electromechanical devices.