The Study Of Single Crystal Copper Nano-contact Process By Molecular Dynamics And Multi-scale Simulation

With the development of the MEMS, the sizes of the devices have become so smaller as to reach the level of micrometer or even nanometer. Due to reduction of the sizes, the micrometer-level and the nanometer-level devices represent the different characters of contact compared with the macro-mechanics during the process of work. The contact properties of those micro-devices directly affect the functionality and the life span of those devices. The contact research under the micro-scale is of great importance to the use and processing of the micro-devices as well as to the overall development of MEMS.The subject comes form the project of National Natural Science Foundation applied by the mentor The Research of the Friction Contact Behavior of Micro Mechanics by Using the Method of Multi-scale Coupling. And it also researches the problems of the micro-devices contact in MEMS. First of all, the paper employs the molecular dynamics method to stimulate nanoindentation process of the single crystal copper of the nanometer scale on the plane and researches the properties of plane contact under the scale of the nanometer. In consideration of the numerous defects on the surfaces of the materials in the practical process of contact, the paper employs the molecular dynamics method to stimulate the sliding friction process of the rigid hemisphere on the defective surface of the single crystal copper and researches the effects on the process of the sliding friction exerted by of the superficial protruding objects.As to the dynamics properties of macroscopic materials, the research process is generally considered to be isotropic. But the crystal materials of the micrometer scale will have effects on the dynamics functionality and the deformation of the materials due to the differences of the crystal direction on the crystal plane. The paper stimulate the nanoindentation process on the single crystal copper’s three different crystal surfaces by employing the molecular dynamics method and researches its dynamics properties and the deformation within the crystal and demonstrates the anisotropy of the copper crystal under the nanometer scale. The molecular dynamics can stimulate the sliding friction during the contact well under the nanometer scale, but it is subject to the restraint of the sizes of the models as well as the ability of the computers, ect. Coupling molecular dynamics method and the finite element can effectively overcome the deficiencies of the molecular dynamics. Researching the multi-scale coupling method and employing the QC, the paper stimulates contact process of the single crystal copper.As to the nanometer contact of the micro scale, the result of the computer stimulation needs to be verified by the concrete experiments. By using the nanoindenter and the AFM, the paper researches the nanoidentaion and the sliding friction of the single crystal copper under the nanometer scale as well as the effects on the nanometer and the nanoscratch exerted by the different crystal surfaces of the single crystal copper.