Papers by Author: Qing Shun Bai

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Authors: Qing Shun Bai, Ying Chun Liang, Ying Xue Yao, Phillip Bex
Abstract: Polycrystalline diamond (PCD) is an ideal tool material for machining high-pressure laminated (HPL) flooring with ceramics overlay. In this paper, the finite element (FE) model of PCD cutter was built firstly, then stress distribution of PCD cutter for machining wear resistance layer embedded with Al2O3 particles was analyzed. The analysis results showed that the stress distribution was variable in rake and flank face of tool, which leads to the final uneven wear profile. Moreover, the test of cutting load was carried out. From the analysis and test, it was shown that PCD cutter was suffering from the fatigue loading of high cycling while machining. At last, a series machining experiments was conducted and the wear characteristics were examined. The analysis results were verified by the wear characteristics of PCD tool. Machining experiments also revealed that the typical micro crack in wear region had great effects on the wear of tool.
Authors: Jia Xuan Chen, Ying Chun Liang, Qing Shun Bai, Yu Lan Tang, Ming Jun Chen
Abstract: Molecular dynamics (MD) simulations of nanometric scratching with diamond tip are conducted on single crystal copper crystal plane (010), and MD simulations are carried out to investigate the mechanism of material removal and the generation of defects on the surface, subsurface and inner of material. During the process of diamond tip scratching the surface of single crystal copper on conditions of different scratching speeds, depths and widths. We achieved the forming details of the chip. While the generation and moving process of defects, such as dislocation, are recorded. The different times of atomic displacement and interaction force are also shown through MD simulation. The evolvement of the lattice pattern in the abrasive processes are analysed by radial distribution function (RDF) and computing the changes of workpiece’s atomic displaces and forces. At the same time, the lattice reconfiguration and the onset and the evolvement process of defects and are analysed by RDF and atomic perspective method, respectively. The simulation results show that scratching speed play role in the course of the form of removing chips, and that different scratching widths and depths of tool have effect on onset and evolvement of lattice defects of workpiece in abrasive processes. This study can give more fundamental understanding of nanosconstruction from atomistic motions and contribute to the design, manufacture and manipulation of nano-devices
Authors: Ying Chun Liang, Kai Yang, Qing Shun Bai, W.Q. Chen
Abstract: In this paper, the effect of minimum chip thickness on cutting temperature in micro-end- milling of aluminum alloy Al2024-T6 using a tungsten-carbide cutter are investigated and analyzed. The three-dimensional coupled thermal-mechanical finite element model is adopted to determine the effects of varying depth of cut on cutting temperature considering size effects. The simulation results show that the cutting temperature in micro-end-milling is lower than those occurring in conventional milling processes. When the depth of cut is approximately 40% of the cutting edge radius, there is no chip formation. The maximum temperature occurs at the contact region between micro cutting edge and workpiece, which shows an obvious size effect. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6 with a high precision infrared camera. The influence of various cutting depths on cutting temperature has been verified in experiments. The experimental measurements results are in a good agreement with the simulation results.
Authors: Qing Shun Bai, Ying Chun Liang, Kai Yang, Zhi Luo, Xiao Yan Fang
Abstract: Micro-mould is a necessary and productive component for the development of MEMS. However, the machining of micro-mould parts with complex 3D surfaces becomes the key problem for the development of micro machinery. In the paper, a new machining technique was introduced to manufacture micro-mould parts. With a reverse engineering technique, point cloud data were acquired and reconstructed into a 3D model of micro mould part in a computer. The numeral control code for micro-machining was also processed with the help of micro-machining simulation. The machining experiment on micro-parts with complex 3D surfaces was conducted on self-developed micro machine tools with micro-diameter ball-end cutter. High quality micro mould parts with complex 3D surfaces were obtained under these micro-milling experiments. The results will provide a perspective resolution on the manufacturing of micro-mould parts with complex surfaces.
Authors: Ying Chun Liang, J.H. Dou, Qing Shun Bai
Abstract: Carbon nanotubes (CNTs) represent ideal Atomic Force Microscope (AFM) tip materials due to their remarkable mechanical properties. Dynamic interactions of a Single-wall Carbon nanotube (SWCNT) indenting towards a monocrystalline hydrogen-free Silicon surface (001) are investigated using molecular dynamic simulation. The critical strain and strain force along the axis of the tube from elastic to plastic regimes are calculated. The simulation shows the deform process in elastic regimes is similar to the process of two ends inward compressed. The atoms of nanotube tip adsorption to the Silicon surface has been observed in the plastic regimes. The mechanical microprocess of AFM’s single-wall Carbon nanotube tip and Silicon surface interactions from elastic to plastic regimes can be well comprehended from the view of nanoscale energetic evolution.
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.
Authors: Kai Yang, Qing Shun Bai, Ying Chun Liang
Abstract: The micro-end-milling process of aluminum alloy Al2024-T6 has been investigated by numerical simulations and experimental approach. The effects of different tool edge radii on the micro-cutter wear were investigated. A three-dimensional finite element model is adopted to determine the effects of tool edge radii on the effective stress and micro-cutter wear during the micro-end-milling process. It is observed that the the tool nose wears out much more quickly due to the high maximal effective stress occurring in this zone. The experimental verification of the simulation model is carried out on a micro-end-milling process of aluminum alloy 2024-T6. The experimental results of the micro-cutter morphologies are in a good agreement with the simulation results. The experimental results show that the model is suitable for studying the mechanism of micro-cutter wear.
Authors: Ying Chun Liang, Hong Min Pen, Qing Shun Bai
Abstract: A multiscale simulation model was built to study the nanometric cutting process of single crystal copper. This multiscale model distinctly reduces the degree of freedom of the whole system compared with full atomistic simulations. Through analyzing the fluctuations of tangential cutting force and strain energy with cutting distance, we confirm that the deformation mechanism of single crystal copper is plastic deformation caused by generation and evolution dislocation. The highest compressive stress locates in shear zone and highest tensile stress locates in the machined surface and subsurface. Simulation results show that there exists a high value of stress around dislocations, which reveals the local high value of stress is the main reason for the generation and evolution of dislocations in the workpiece material.
Authors: Hong Min Pen, Qing Shun Bai, Ying Chun Liang
Abstract: Quasicontinuum simulation of nanometric cutting was conducted on single crystal copper to investigate the effect of crystal orientation and cutting direction on nature of deformation of this material. The model reduces the degrees of freedom in simulations of nanometric cutting process without sacrificing important physics. The simulation results show the crystal orientation and cutting direction have a significant effect on the nature of deformation of nanometric cutting process. In addition, the variations of strain energy of workpiece atoms in different crystal set-ups are investigated.
Authors: Ying Chun Liang, De Gang Li, Qing Shun Bai, Yu Lan Tang
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.
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