Research On Single-crystal Nickel Nano-machining By Molecular Dynamics Simulation

Ultra precision machining has been developed into a kind of high accuracy processing technology by the needs of nuclear energy,large scale integrated circuit,laser and space of cutting-edge industry,and become a hot topic of research in the field of mechanical manufacturing.This paper regards single-crystal nickel which is widely used in the aerospace as the object of analysis by studying its machining mechanism.The molecular dynamics method is a powerful tool for studying such issues.It can not only obtain the atom movement details,but also do all kinds of simulation experimental observations,especially some microscopic details,which could not get in the real experiment.Under the foundation of molecular dynamics basic principles and algorithms,the single crystal nickel micro cutting model is established by setting the cutting tool material to the rigid body.The LAMMPS simulation software is employed to simulate the machining process.Machining process transient atomic diagram and related characteristics are achieved by VMD and OVITO visualization of simulation results.The researches on the mechanism of the single crystal nano-machining nickel processing can mainly be divided into the following several aspects.Firstly,a reasonable explanation is given to the formation process of chip and machined surface during single-crystal nickel machining process by observing different steps of transient image in molecular dynamics simulation.Secondly,the transformations of physical state at the microscopic scale during the cutting process are analyzed according to the change of temperature and cutting force in different time period.The energy conversion and thermodynamic relationship in molecular dynamics simulation are achieved by the distribution of kinetic energy of work-piece during the cutting process.Moreover,a research on defect structure has analyzed the dislocation nucleation,movement and distribution characteristics under different conditions and different phases,and explains the variation rule of cutting force and temperature with the dislocation theory.Lastly,the effect of cutting speed on single crystal nickel machining process was studied from the angles of cutting force,temperature,potential energy and dislocation respectively.On the basis of the analysis results,the paper draws the main conclusions,and puts forward suggestions for the future research.