Papers by Keyword: Nanocutting

Abstract: A simulation of the material removal by a single abrasive grain in nanometric grinding is presented in this paper. Molecular Dynamics method is used for modeling the diamond grain and the copper workpiece. The Morse potential function is used to simulate the interactions between the atoms involved in the procedure. The abrasive grain follows a trajectory with decreasing depth of cut within the workpiece to simulate the interaction of the grain with the workpiece. The influence of the grain shape, being either square or rectangular, and of the orientation of the grain, where the grain has rake angle 10^o, -10^o and-20^o, are studied. From the analysis it is apparent that both grain morphology and orientation play a significant role on chip formation, grinding forces and temperatures. With the appropriate modifications, the proposed model can be used for the simulation of various nanomachining processes and operations, in which continuum mechanics cannot be applied or experimental techniques are subjected to limitations.

Abstract: . This study successfully simulated the single crystal copper nanocutting by a rigid body /elastic tools with nose radius at the nitrogen gas environment using molecular dynamics, and analyzed the workpiece temperature distribution and dislocation during nanocutting. After simulations, it can be found that when cutting with the elastic body tool, the tool itself was still distorted slightly, however, the cutting results of the elastic tool and the rigid body tool of the tool are not the same. The chip temperature was highest near the central rake and nose.The workpiece temperature when the elastic body tool cutting was lower; the temperature in the nose and rake plane is the highest, the more away from the nose, the lower the temperature.

Abstract: Molecular dynamics simulations method is used on the study of material deformation in monocrystal silicon during nanomachining. Both nanoindentation and nanocutting by a diamond tool tip is investigated using LAMMPS. Characterization methods such as coordination number and labeling atoms in different layers have been adopted to study the law of transformation. As the surface atoms are tracked, their transformation law is analyzed and the formation mechanism of the cuttings and finished surface is announced. The impact crystal orientation of silicon on the machining is also studied.

Abstract: The three-dimensional quasi-steady molecular statics nanocutting model developed by this paper carries out simulation analysis of nanocutting of sapphire substrate in order to explore the effects of tools with the same tip radii of probe and straight-line cutting at different cutting depths, on cutting force. The three-dimensional quasi-steady molecular statics nanocutting sapphire workpiece model first assumes the trajectory of each atom of the sapphire workpiecs being cut whenever the diamond cutter goes forward one step. It then uses the optimization search method to solve the force equilibrium equation of the Morse force in the X, Y and Z directions when each atom moves a small distance, so as to find the new movement position of each atom, and step by step calculates the behavior during cutting. And from the simulation results of cutting force, down force and side force, it is found that under the actions of cutting tools with the same tip radius of probe, cutting force enlarges with the increase of cutting depth. This result is identical to the actual experimental phenomena of nanocutting. From this, it is known that the simulation model developed in this study is reasonable.

Abstract: Three dimensional molecular dynamics simulation on the nanocutting of monocrystalline silicon is carried out to investigate the material deformation behaviors and atomic motion characteristics of the machined workpiece. A deformation criterion is developed to determine the material deformation and phase transformation behavior in the subsurface layer based on the single-atom potential energy variations. The results show that the machined chips suffer a complex phase transformation and eventually present an amorphous structure caused by the plastic deformation behavior. A polycrystalline structure is obtained on the machined surface. Both plastic and elastic deformation simultaneously takes place on the machined surface, and elastic deformation takes place under the machined surface. In order to further unveil the mechanism of nanocutting process, the displacements of all atoms are also simulated. The simulation results shows that different atomic motions occur in different regions in the workpiece, and the chips formations occur via extrusion.

Abstract: In contrast to microscale method (molecular dynamics) or macroscale method (FEM), multiscale modeling is a new, fast developing and challenging scientific field with contributions from many scientific disciplines in an effort to assure materials simulation across length/time scale. In this paper we propose MPM/MD handshaking method to establish multiscale modeling of thin film formation/nanocutting. First, the detailed handshaking method is presented for large scale simulation along with basic principles of the multiscale approach. Then, quantitative items: flatness, cutting force, adhesion between cluster and substrate, etc. are provided to avoid drawbacks of current qualitative manner. Finally, simulations are carried out to clarify the efficiency of system.

Abstract: This paper investigates the deformation in monocrystalline silicon subjected to single-point cutting with the cutting speed up to 46.78 m/s, the depth of cut of 2 μm, and the feed rate of 5 and 30 μm/rev. Raman spectroscopy and transmission electron microscopy were used to characterize the subsurface damages. It was found that the increase of either the feed rate or cutting speed increases the thickness of amorphous layer and penetration depth of dislocations. At the feed rate of 30 μm/rev and cutting speed of 12.48 m/s, a new dislocation system was initiated. An unknown peak was detected by Raman spectroscopy, which may indicate an unknown Si phase.

Abstract: The stress induced in a workpiece under nanocutting are analyzed by an atomic-scale model approach that is based on the energy minimization. Certain aspects of the deformation evolution during the process of nanocutting are addressed. This method needs less computational efforts than traditional molecular dynamics (MD) calculations. The simulation results demonstrate that the microscopic cutting deformation mechanism in the nanocutting process can be regarded as the instability of the crystalline structure in our atomistic simulations and the surface quality of the finished workpiece varies with the cutting depth.

Abstract: To investigate the effect of tool geometry on single-crystal silicon nano-cutting, parallel molecular dynamics (MD) simulations are carried out with different tool rake angles. In this study, a parallel arithmetic based on mechanism of spatial decomposition together with MD is applied to simulate nano-cutting processes of single-crystal silicon (100) plane by using a single-crystal diamond tool. The simulation results show that tool rake angle has great effects on cutting forces and subsurface stress, and the effect of tool rake angle variation on work-piece potential energy is not evident while cutting single-crystal Silicon (100) plane. Moreover, the analysis of cutting forces and potential energy show that there is not evident dislocation in the nano-cutting.