Papers by Author: Xing Lei Hu

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Authors: Xing Lei Hu, Ya Zhou Sun, Ying Chun Liang, Jia Xuan Chen
Abstract: Monte Carlo (MC) method and molecular dynamics (MD) are combined to analyze the influence of ageing on mechanical properties of machined nanostructures. Single crystal copper workpiece is first cut in MD simulation, and then the machined workpiece is used in MC simulation of ageing process, finally the tensile mechanical properties of machined nanostructures before and after ageing are investigated by MD simulation. The results show that machining process and ageing have obvious influence of tensile mechanical properties. After machining, the yield strength, yield strain, fracture strain and elastic modulus reduce by 36.02%, 28.86%, 20.79% and 7.16% respectively. However, the yield strength, yield strain and elastic modulus increase by 4.84%, 1.41% and 1.02% respectively, fracture strain reduce by 24.53% after ageing process. To research the ageing processes of machined nanostructures by MC simulation is both practical and meaningful.
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Authors: Jia Xuan Chen, Ying Chun Liang, Li Quan Wang, Xing Lei Hu
Abstract: Three-dimensional molecular dynamics simulations are performed to investigate the AFM-based nanometric cutting process of single crystal copper. The effects of cutting velocities (180, 360, and720 m/s) on the cutting force, the ratio of the thrust force and cutting force and subsurface layers. The results show that the dislocations nucleate beneath the tool, and propagate along the [-11-1] direction in the (111) plane. The effects of the nanocutting action from the tool on the subsurface damaged layers decrease gradually as the distance from the tool tip increases. With the increasing cutting speed, the cutting forces increase accordingly. However, the ratio of the the ratio the thrust force and cutting force decrease as the cutting speeds increase. With the proceeding of the cutting process, that tends to the same on the whole.
448
Authors: Xing Lei Hu, Ya Zhou Sun, Ying Chun Liang, Jia Xuan Chen
Abstract: A three-dimensional model of Monte Carlo (MC) simulation is proposed to study the effects of ageing on the surface quality of machined nanostructures. The model includes the utilization of the Morse potential function to simulate the interatomic force between the atoms in workpieces. The results show that the ageing processes have important influence on the surface morphology and internal structure of machined workpiece. Most of the disordered point defects and one large stacking fault structures in machined workpiece disappear after ageing, but still some defect structures remain. In addition, distribution of atomic potential and atomic stress in the workpiece become regular in the aging process, and the atoms of the defect structures have much higher potential energy and stress. Finally, surface roughness of machined workpiece definitely increases after ageing. To analyze the morphology of machined surface after ageing is very practical and meaningful.
108
Authors: Xing Lei Hu, Jia Xuan Chen, Ying Chun Liang
Abstract: This paper provides a review of Monte Carlo (MC) method and its applications in mechanical engineering. MC simulation is a class of computational algorithms which require repeated random sampling and statistical analysis to calculate the results. The basic principles, formulas and recent development of Monte Carlo method are firstly discussed briefly, and then the applications of MC simulations in the design and manufacturing of nanostructures are reviewed. Finally, we briefly introduce MC simulation of morphology evolution of machined surface, which come from our recent work.
154
Authors: Ying Chun Liang, Xing Lei Hu, Jia Xuan Chen
Abstract: Monte Carlo (MC) method is adopted to simulate the morphology evolution of machined surface. One specimen is first scratched in MD simulation, and then the machined surface is used in MC simulation. It is found that the atoms stacking on both sides of the groove in the process of nanoscratching have relative obvious migration with time, because these atoms are in high energy, unstable status. The atoms are moved to the minimum energy position by repeated Markov moves. These atoms have an average one-atom-high migration, so quality of machined surface is definitely influenced by the factor of time. To simulate morphology of machined surface by MC simulation is both practical and meaningful.
291
Authors: Ying Chun Liang, Hong Min Pen, Qing Shun Bai, Xing Lei Hu, Zhi Guo Wang
Abstract: In order to investigate the mechanical properties of single crystal Cu nanorod with preset defects, the multiscale unixial tension simulation models of nanorods with two different crystallographic orientations are established. In two orientations, the dislocations are emitted firstly from the notch tip. The results show that the defect evolution, stress-strain curves and train energy vary with different crystallographic orientations. In setup, the deformation is ductile mode and it is fracture fashion in the setup.
1073
Authors: Ying Chun Liang, Xing Lei Hu, Jia Xuan Chen, Hong Min Pen
Abstract: Nanometric uniaxial tension tests of single crystal copper nanorod are simulated using multiscale simulation method, which has combined molecular dynamics (MD) and finite element method (FEM). New tension models of nanorod are constructed. Tension processes of ideal nanorod without notches and that with notches are performed to analyze their mechanical properties. Deformation mechanism of tension process is discussed in detail. Yield strength and elastic modulus are calculated according to the obtained stress-strain curves. Finally, the results show that the notches have obvious influence on the mechanical properties of copper nanorod. Due to the existence of notches, the section area of single crystal nanorod decreases by 40%; however, the yield strength and elastic modulus decreases by 39.0% and 10.2% respectively in our simulations. This research is helpful for identifying the mechanical properties of single crystal copper nanorod, and for understanding the deformation mechanism of tension process of nanorod.
2712
Authors: Xing Lei Hu, Ying Chun Liang, Jia Xuan Chen, Hong Min Pen
Abstract: Quasicontinuum simulations of tension test of single crystal copper nanowire are performed to analyze deformation mechanism of tension process and size effects of mechanical properties. New tension models of nanowire are constructed by using quasicontinuum method, which has combined molecular dynamics and finite element method. Tension processes of three different length nanowires without notches and those with notches are simulated. Yield strength and elastic modulus are calculated according to the obtained load-displacement curves. Finally, the results show that the mechanical properties of copper nanowire have obvious size effect and the notches have obvious influence on the mechanical properties.
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