Papers by Author: Ying Chun Liang

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Authors: Bo Wen Zhang, Yong Da Yan, Zhen Jiang Hu, Xue Sen Zhao, Ying Chun Liang, Wei Dong Fei, Shen Dong
Abstract: As the dimensions of parts become smaller, understanding the mechanical properties of these small components was becoming more important. Till present day, the methods and technology used to investigate the deformation behavior in nanoscale were still lacking. In this paper, the specimens were single crystal copper wires with diameter in 50 microns. Atomic force microscope integrated with an in- situ tensile system were used to determine the mechanical behavior of copper wires and observe the surface topography deformation in nanoscale simultaneously. The results were as follows: the modulus of elasticity, tensile strength and failure strain of the sample were 167Gpa, 0.564GPa and 0.011, respectively. By using AFM, the separation process between the copper wire and impurities on it, such as oxide film, was observed. The nanoscale deformation process of the copper wire was also obtained.
Authors: Xiao Li Zhao, Shen Dong, Ying Chun Liang, T. Sun, Yong Da Yan
Abstract: Atom Force Microscopy (AFM) can be employed to create surfaces in Si substrate with recessed features. The resulting patterns can serve as masters to make the required elastomeric stamps for soft lithography. Morphology analysis of patterned features on Si substrate and polydimethylsiloxane (PDMS) stamp by AFM imaging confirms that pattern can be successfully transferred from Si substrates to PDMS stamps. It is shown that this method for creating masters can be performed with an AFM, making this method particularly straightforward, economical and accessible to a large technical community that are provided with AFM for measurement.
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.
Authors: Yong Da Yan, T. Sun, Shen Dong, Ying Chun Liang, K. Cheng
Authors: Ya Zhou Sun, Xue Mei Yu, Hai Tao Liu, Ying Chun Liang
Abstract: Porous materials have been successfully used in an aerostatic bearing. In this paper, the dynamic stiffness and damping of partial porous aerostatic thrust bearings are analyzed by numerical calculation method. Firstly, the pressure distribution function of the bearing is divided into the static and dynamic pressure distribution functions through minor perturbation method. Then, the static and dynamic pressure distribution functions are calculated by FEM. Finally, the dynamic stiffness and damping coefficients of the bearing are solved. The result indicates that the dynamic stiffness increases obviously with the increment of supply pressure and first increases then decreases with the increment of frequency, and that there is negative damping in the low frequency band and the supply pressure has a great impact on the stability of the bearing.
Authors: Ming Jun Chen, Jing He Wang, X.M. Chen, Ying Chun Liang
Abstract: In order to study mechanical property with different crystal-plane and different crystal orientation of the crystal KDP, nano-indentation experiments are first done. The mechanical properties of crystal KDP, such as elastic modulus, yielding stress, are obtained from the analysis of the experimental curve. To obtatin the stress-strain curves of crystal KDP, by using the spherical tip can get characteristic of continuous strain, the spherical indentation experiments is proposed firstly and carried out. According to obtained parameters, A finite element cutting model of crystal KDP is established. The cutting process of crystal KDP is simulated by the model, and the influence of rake angle and depth of cut on chip and surface quality is studied. The theory shows that when the cutter’s rake angle is in the range of -40° to -45°, an perfect super-smooth KDP crystal surface will be obtained. Finaly, the experiments is carried out on special ultra-precision machine tool for crystal KDP by ourself devoloping. Experiment results show that when the cutter’s rake angle is about -45°, an super-smooth surface (rms: 6.521nm and Ra: 5.151nm )is obtained on the plane (001), and this experiment certified correctness of theory analysis.
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: Yong Zhi Cao, Shen Dong, Ying Chun Liang, Tao Sun, Yong Da Yan
Abstract: Ultrathin block copolymer films are promising candidates for bottom-up nanotemplates in hybrid organic-inorganic electronic, optical, and magnetic devices. Key to many future applications is the long range ordering and precise placement of the phase-separated nanoscale domains. In this paper, a combined top-down/bottom-up hierarchical approach is presented on how to fabricate massive arrays of aligned nanoscale domains by means of the self-assembly of asymmetric poly (styrene-block-ethylene/butylenes-block-styrene) (SEBS) tirblock copolymers in confinement. The periodic arrays of the poly domains were orientated via the introduction of AFM micromachining technique as a tool for locally controlling the self-assembly process of triblock copolymers by the topography of the silicon nitride substrate. Using the controlled movement of 2- dimensional precision stage and the micro pressure force between the tip and the surface by computer control system, an artificial topographic pattern on the substrate can be fabricated precisely. Coupled with solvent annealing technique to direct the assembly of block copolymer, this method provides new routes for fabricating ordered nanostructure. This graphoepitaxial methodology can be exploited in hybrid hard/soft condensed matter systems for a variety of applications. Moreover, Pairing top-down and bottom-up techniques is a promising, and perhaps necessary, bridge between the parallel self-assembly of molecules and the structural control of current technology.
Authors: Zong Wei Xu, Ying Chun Liang, Shen Dong, Li Qiang Gu, T. Sun, Qing Liang Zhao
Abstract: An improved arc welding method was developed to fabricate carbon nanotube probe under direct view of optical microscope. The new fabrication method here needs not coat silicon probe in advance with metal film, which greatly reduces the fabrication’s difficulty. An easy method for shortening the nanotube probe was also developed. The improved fabrication method here is simple and reliable. The fabricated carbon nanotube probe showed good properties of higher length-to-diameter aspect ratio, better wear characteristics than silicon probe.
Authors: Chyan Bin Hwu, Ying Chun Liang
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