e-Engineering & Digital Enterprise Technology

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Authors: Ying Xue Yao, Dong Li Qin, L. Zhou
Abstract: The influence of parameters to load performances of a high-speed externally pressurized spherical gas bearing compensated by two-rows of orifices has been studied numerically based on finite element method (FEM). Reynolds equation governing the flow field in the clearance space in spherical coordinates system is transformed into a analogous style in Descartesian coordinates by parameter substitution, and Galerkin weighted residual method is applied to reduce the order of derivatives of the transformed equation. Pressure distribution on the gas-film is obtained by solving of the equation. On the basis of theories, influences of rotating speed, nominal gas-film thickness and supplying pressure to load carrying capacity and stiffness are analyzed. Comparison of performances between hydrostatic and hybrid state of the bearing has also presented.
732
Authors: S.C. Wang, J. Han, Jian Feng Li, Zhi Nong Li
Abstract: Because of the deficiency of fixed kernel in bilinear time-frequency distribution (TFD), i.e. for each mapping, the resulting time-frequency representation is satisfactory only for a limited class of signals, a new adaptive kernel function named the radial parabola kernel (RPK), is proposed. The RPK can adopt the optimizing method to filter cross-terms adaptively according to the signal distribution, obtain good time-frequency resolution, and offer improved TFD for a large class of signals. Compared with traditional fixed -kernel functions, such as Wigner-Ville distribution, Choi-Willams distribution and Cone-kernel distribution, the superiority of the RPK function is obvious. At last, the RPK function is applied to the analysis of vibration signals of bearing, and the result proves the RPK function an effective method in analyzing signals.
737
Authors: Guo Sheng Geng, Jiu Hua Xu
Abstract: This research is concerned with the influences of cutting speed on the fatigue properties of high speed milled Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy. Four different cutting speeds ranging from 50 to 200m/min were used to mill the specimens for fatigue test, and the fatigue properties of them were studied at two stress levels: 80—800MPa and 90—900MPa. The fatigue lives of the specimens milled under different cutting speeds were compared. The fracture surfaces were analyzed using scanning electron microscope (SEM), and cyclic stress-strain properties of TA15 titanium alloy were investigated with a stress-strain gauge. The results showed that increasing cutting speed can help to improve the fatigue properties of titanium alloy, especially at a relatively low cyclic stress level.
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Authors: Jian Cao, Y.L. Dong, H.G. Xu, Q.H. Zhang
Abstract: This paper analyzes the compaction structure of New Vane-Hydraulic Motor, design and calculates the parameter of spring which is used at the bottom of the vane; it also calculates the actual pressure angle which is operated between the vane and the stator in order to find a method to diminish the size of pressure angle.
747
Authors: E.L. Liu, Rong Di Han, Zhen Jia Li, Hui Ping Zhang, Guo Liang Wei
Abstract: As machining technology develops toward the unmanned and automated system, the need for chip-breaking control is considered increasingly important. In this paper, chip-breaking limit of 3-D complicated groove insert is proposed according to cutting experiments. The mathematical formulation of chip section profile coefficient is established through the analysis of influential effect of 3-D complicated groove on chip section profile. The chip-breaking model is developed to predict the critical feed rate and the critical depth of cut in machining based on analyzing the restricted effect of 3-D complicated groove on chips. Finally, a full experimental validation of the analytical model is presented for chip breaking when the workpiece is steel, 45. The testing results show the critical feed rate model and critical depth of cut model are reasonable and reliable.
752
Authors: Yong Gang Kang, Zhong Qi Wang, J.J. Wu, Cheng Yu Jiang
Abstract: An efficient flexible iterative algorithm with a general approach is presented for calculations of surface form errors in peripheral milling of thin-walled workpiece. An efficient finite-element model for tool/workpiece is presented to analyze the surface dimensional errors in peripheral milling of aerospace thin-walled workpieces. The efficient flexible iterative algorithm is proposed to calculate the deflections and the maximum surface form errors as contrasted with the rigid iterative algorithm used in the literatures. Meanwhile, some key techniques such as the finite-element modeling of the tool-workpiece system; the determinant algorithm to judge instantaneous immersion boundaries between a cutter element and the workpiece; iterative scheme for the calculations of tool-workpiece deflections considering the former convergence cutting position are developed and the method for calculating the position and magnitude of the maximum surface form errors are developed and presented in detail. The proposed approach is validated and proved to be efficient through comparing the obtained numerical results with the test results.
757
Authors: P. Wang, D.L. Liu, Yi Zhi Liu, Xian Li Liu, Chun Ya Wu
Abstract: The Polycrystalline Cubic Boron Nitride (PCBN) cutting tools has have been developed for high speed machining in modern automation manufacture. The machining surface roughness is regarded as an important criterion to assess PCBN cutting tools performance. There are too many problems in conventional detection method. In order to solve that problem, we present a new way that is based on image analysis of machining surface texture to assess surface roughness. The new method is consisted of three steps. It captures surface texture image when machining is finished or pauses. Firstly, RGB histogram is adopted to analyze image pixel information. This means takes advantage of histogram technique and provides more pixel distribution information than gray histogram. Secondly, unsupervised texture segmentation is used based on resonance algorithm. Thirdly, a new estimation parameter E that is the density of surface contour peak is put forward to estimate machining surface roughness.
762
Authors: Zhao Liang Jiang, Shi Hong Feng, M.F. Qi, Zhao Qian Li
Abstract: In order to protect ERP system information from authorized users or non- trusted users, a trusted role based access control model was proposed. Combined with the characteristics of enterprises, trusted computation for user is designed to support roles assignment to the users. Meanwhile, Object Lifecycle States (OLSs) are presented for efficient access control to objects. Based on the value of trusted computation, users are assigned the corresponding roles to access control various resources. Finally, there is an empirical research on an ERP System implemented in a manufacturing enterprise.
767
Authors: Chang Fu Zhang, D.J. Lu, Zhuang De Jiang
Abstract: To enable designers to construct geometric models of MEMS devices in a straightforward environment and get mask and process flow automatically, a 3D MEMS CAD system for surface micromachined devices is proposed based on traditional design software—SolidWorks. With Application Programming Interfaces (APIs) of SolidWorks, component modules and databases of the system are developed with Visual Basic, such as geometric model design module, mask and process flow generation module, process simulation module, 3D feature database and material database. Their development method is discussed in this paper. A practical example shows that surface micromachined devices can be designed efficiently in the system without tedious fabrication process.
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Authors: Yang Wang, Han Ming Lv, Shi Jun Ji
Abstract: A triangle mesh was reconstructed from an unorganized point cloud through two phases of mesh growing based on different strategies, where regions with high point density usually grow at the first phase and the remaining regions grow later. In each phase of mesh growing, the smoothest regions always grow firstly and then largely avoid errors emerging in sharp regions. The presented test technique of geometric integrity as well as the abnormality disposing method pledged the reconstructed mesh has correct geometry structure. Experiments show that the algorithm is efficient and effective.
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