Molecular Dynamics Simulation On Thermal Buckling And Vibration Properties Of Nano-rod

Metal nanowires have many applications as key building blocks and active components in nano-devices due to these superior properties. The change of temperature will have a great effect on its performance. So it is important to study the mechanical properties in order to design and manufacture nano-structures. In the course of the study, the experimental methods have various limitations, while the simulation technology can be very convenient to predict the performance of the object. Molecular dynamics simulation is one of the important methods. In this paper, the thermal buckling and vibration of nano-rod were simulated by molecular dynamics simulation.Based on the Lammps platform, the thermal buckling of the nano-rod was simulated. The axial stress of thermal buckling decreases with the increase of the ratio of the length to diameter. In the elastic deformation stage, the simulation results are consistent with the theoretical values calculated by the effective elastic modulus. In the case of the same ratio of length to diameter, because of the influence of the surface effect, the axial stress of the nano-rod increases with the increase of cross section area, and it also has a higher critical buckling temperature. Nano-rod with two kinds of crystal orientations were established, and it was found that the [111] nano-rod had higher axial stress at the time of buckling.Nano-rods with vacancies were established by the method of randomly deleting atoms. Under the same slenderness ratio, the buckling stress decreases with the increase of vacancy density, the critical buckling temperature decreases slightly. When the vacancy density reaches 3%, the slip occurs along {111} plane, the buckling stress is obviously reduced. The buckling stress of the nano-rod was found to decrease with the increase of the ratio of the slenderness ratio. We added holes in the nano-rod. The critical buckling stress decreases greatly when the radius reached to 7 times of lattice constant.The vibration of the nano-rod was produced by the stretching method. In transverse vibration, the fundamental frequency decreases with the increase of length, and increases with the increase of width. It is a linear relationship, which is consistent with the classical Euler beam theory. In the longitudinal vibration, the fundamental frequency decreases with the increase of the length. The elastic modulus was affected by the surface effect, which leads to the increase of the fundamental frequency with the increase of the width. At the same time, the results calculated by Liang’s elastic modulus is more close to the molecular dynamics simulation results than the macro elastic modulus. In the transverse vibration, the fundamental frequency of the nano-rod with different cross section decreased with the increase of temperature.