Molecular Dynamics Simulation Of Bimetal Rolling Nanoscale Problems

With the development of modern science and nanotechnology, the behavior of nanoscale has been attracting more and more attention. As the difficulties of experimental and theoretical studies, molecular dynamics simulation has been a powerful tool to explore nanoscale problems. Molecular dynamics simulation theoris base on the hypotheses of statistics mechanics. According to the hypothesis, the number of sample systems which statistical ensemble consists of must be so large that they can denote various probable states, and reflect the probability of these microscopic states. Enough observing time is the precondition for statistic. Because the ability of computer, it is difficult to realize the two request for statistic demands absolutely. Comparing with 3-D model, the same size 2-D model can save a great deal of simulation time. With this advantage of 2-D model, it becomes possible to delay the observing time and enlarge the model size, also can reduce the affect of boundary condition such as periodicity, total reflection and diffuse reflection.In this paper, the rolling process of metal material at nanoscale is simulated by molecular dynamics simulation and the variation of materials'mechanical property at nanoscale is researched. In simulation of single copper molecule, using embedded atom method. In simulation of bimetal of silver-nickel molecule, useing Lennard-Jones potential functions. The simulation is used Verlet numerical method of integration, and velocity scaling method to control the system temperature. We create and analyse the model of simulation in VC++ language. Firstly, we studied variations of systemic kinetic energy and potential energy during the relaxation process. With the change of time, atoms distributed in crystal lattice started moving freely affected by applied force between atoms. When the atoms are droved to an equilibrium position, systemic kinetic energy, potential energy are also droved to a stable value accordingly. Then exerting method of adding force to atoms on the end face, we studied variation of parameters of system and got evolution of atoms'positions during the rolling process. The surface of model was damaged by external applied load, and the new atomic bonds were produced between two different atoms. Recording data during loading, we can get the curvilinear figure of displacement of the end face with the increase of loading time step. Finally we simulated and compared the influence of rolling process of bimetal of silver-nickel in different temperatures.