Jun 2007, Volume 2 Issue 2
    

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  • Residual stresses in coating-based systems, part II: Optimal designing methodologies
    ZHANG Xiancheng, WU Yixiong, XU Binshi, WANG Haidou
    2007, 2(2): 125-136. https://doi.org/10.1007/s11465-007-0022-x
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    In this part of the work, different cases are studied to illustrate the implementation of the analytical models that have been developed in Part I [Front. Mech. Eng. China, 2007, 2(1): 1 12]. Different topics are involved in the optimal design of coating-based systems. Some essential relations among material properties and dimensions of the coating and substrate and the residual stress variations are reflected. For the multilayered coating-based systems, some optimal design methodologies are proposed, such as the decrease in stress discontinuity at the interface between the adjacent layers, the curvature as a function of the coating thickness, the effect of the interlayer on the residual stress redistribution, and so on. For the single-layered coating-based systems, some typical approximations that are often used to predict the residual stresses in the coating-based system or bilayer structure are corrected. A simplified model for predicting the quenching stress in a coating is also developed.
  • Theoretical and experimental analysis on super precision grinding of monocrystal silicon
    GUO Xiaoguang, GUO Dongming, KANG Renke, JIN Zhuji
    2007, 2(2): 137-143. https://doi.org/10.1007/s11465-007-0023-9
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    Through investigating the diamond-silicon grinding system, the grinding mechanism, including chip removal and subsurface damage, is discussed with the aid of the molecular dynamics (MD) approach and grinding experiments. Based on MD simulation, nanometric-grinding mechanism is analyzed from the viewpoint of instantaneous distribution of atoms, grinding force, and the potential energy between atoms and the profile of the groove. The simulation results show that some silicon atoms are deformed and piled up in front and on two sides of the abrasive surface because of the extrusion and cutting. When the energy in silicon lattice reaches its maximum value, the bonds of silicon atoms are broken and the material is removed. With the advancement of the abrasive, the silicon lattice under the abrasive surface is fractured, and then the amorphous layers are formed and propagated, which causes the subsurface damage. At the same time, some amorphous atoms are reconstructed and the degenerating layer of the machined surface is formed. Besides, the recovery of elatstic deformation occurs in the machined surface of the workpiece. In addition, the grinding experiment and profile detection with the aid of the measurment for 3D profiling are performed to verify the simulation results. The good agreement in the profile of the groove between the experimental value and the simulating value shows that MD simulation is very effective and reliable, and successful to fulfill the investigation on nanometric machining mechanism.
  • Research on the valveless piezoelectric pump with Y-shape pipes
    ZHANG Jianhui, LU Jizhuang, XIA Qixiao
    2007, 2(2): 144-151. https://doi.org/10.1007/s11465-007-0024-8
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    A piezoelectric pump with its Y-shape elements is presented. Two Y-shape pipes are fixed outside the chamber serving as an inlet and outlet, with the chamber and a piezoelectric vibrator being the actor. The pump has the potential to be miniaturized and integrated. Eddies occurring in the Y-shape elements are smaller, which is beneficial for the transport of living cells or long-link macromolecules. In this paper, the structure of the pump is first presented. Then, the equations on the change in volume and the mean pressure in the chamber are established, as well as the relation between the flow rate and the working frequency of the piezoelectric vibrator. Moreover, the relation between the mean pressure in the chamber and the working frequency of the piezoelectric vibrator is established. Finally, experiments are carried out to test the characteristics of the pump and to verify the correction of the theory on this pump.
  • Analysis of the dynamic stress of planar flexible-links parallel robots
    DU Zhaocai, YU Yueqing, YANG Jianxin
    2007, 2(2): 152-158. https://doi.org/10.1007/s11465-007-0025-7
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    This paper presents a method for the dynamic stress analysis of planar parallel robots with flexible links and a rigid moving platform. The finite element-based dynamic model of flexible parallel robots is proposed. The relation between elastic deformations and elastic displacements of the flexible links is investigated, considering the coupling effects of elastic motion and rigid motion. The elastic deformations of links are calculated. Considering the effects of bending-shearing strain and tensile-compression strain, the dynamic stress of the links and its position are derived by using the Kineto-Elastodynamics theory and the Timoshenko beam theory. Due to the flexibility of the links, the dynamic stresses are well illustrated through numerical simulation. Compared with the results of the finite element software SAMCEF, the numerical simulation results show the good coherence and advantages of the analysis method. The dynamic stress analysis is demonstrated to have a significant impact on the analysis, design and control of flexible parallel robots.
  • Digital design of a combine harvester using virtual prototyping
    YAN Chuliang, LI Jie, ZHANG Shuming, YANG Fangfei
    2007, 2(2): 159-163. https://doi.org/10.1007/s11465-007-0026-6
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    A parametric feature-based modeling was used to model the parts of a combine harvester. The digital virtual prototyping of the harvester was completed by virtual assembly. The finite element analysis of the vehicle frame was made and the result satisfied the requirements. The vibration sieve, which is a key part of the combine harvester, was simulated and optimized. The excellent parameters of the vibration were gained by optimization. The grain passed through the sieve easily after the optimization and reduced the loss rate and impurity rate in theory.
  • A novel decoupling approach to an integrated optical-fiber proximity sensor for robots
    LIU Guixiong, LI Xiani
    2007, 2(2): 164-167. https://doi.org/10.1007/s11465-007-0027-5
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    The structure and the working principle of a self-compensational integrated optical-fiber proximity sensor that detects distance and orientation are introduced in this paper. The corresponding decoupling approach to the sensor is presented on the basis of multiscale characteristics. The decoupling process can be divided into two parts: classifying the information on the basis of the multiscale degree and solving the coupling equation via the computational approximation methods with different precisions. Finally, the principle, the physical meaning, and the implementation process of the approach are discussed. They indicate that the proposed approach is real-time and accurate, and can be applied to other similar circumstances.
  • Fuzzy force control of constrained robot manipulators based on impedance model in an unknown environment
    LIU Hongyi, WANG Fei, WANG Lei
    2007, 2(2): 168-174. https://doi.org/10.1007/s11465-007-0028-4
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    To precisely implement the force control of robot manipulators in an unknown environment, a control strategy based on fuzzy prediction of the reference trajectory in the impedance model is developed. The force tracking experiments are executed in an open-architecture control system with different tracking velocities, different desired forces, different contact stiffnesses and different surface figurations. The corresponding force control results are compared and analyzed. The influences of unknown parameters of the environment on the contact force are analyzed based on experimental data, and the tunings of predictive scale factors are illustrated. The experimental results show that the desired trajectory in the impedance model is predicted exactly and rapidly in the cases that the contact surface is unknown, the contact stiffness changes, and the fuzzy force control algorithm has high adaptability to the unknown environment.
  • Thermal deflection analysis of the solidified shell in continuous casting of slab
    LIU Hongzhao, WANG Zhongmin
    2007, 2(2): 175-179. https://doi.org/10.1007/s11465-007-0029-3
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    The thermal deformation problem in the continuous casting of a slab subjected to thermal loading because of the temperature gradient along the solidified shell thickness is investigated. On the basis of the reciprocal theorem of work or Betti-Maxwell s reciprocal theorem and the superposition principle, the deflection expressions for a rectangular plate with the two opposite edges simply supported, and the other two opposite edges clamped under the action of the uniformly distributed load and nonuniform temperature field are derived respectively. The meaning of each term in the deflection expression obtained by the reciprocal theorem of work is explained. Then the practical example is given to calculate the thermal deformation and the bulging deformation of the solidified shell under three tension speeds. This research is useful for analyzing the bulging deformation in the continuous casting of a slab under the static pressure of the molten steel and the thermal loading because of the temperature gradient along the solidified shell thickness.
  • Directional solidification of metal-gas eutectic and fabrication of regular porous metals
    LIU Yuan, LI Yanxiang, WAN Jiang
    2007, 2(2): 180-183. https://doi.org/10.1007/s11465-007-0030-x
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    Directional solidification of metal-gas eutectic (Gasar) is a novel process for making regular porous metals. This process is based on a solid-gas eutectic reaction involving a gaseous medium and a metal or ceramic phase. The process easily controls the porosity, the pore size, the pore orientation, and the pore morphology when the melting and solidifying conditions are varied in a wide range. The latest progress and our research work are reviewed in this paper.
  • Emergency design framework: a satellite preliminary scheme design
    TENG Hongfei, WANG Yishou, ZHANG Bao
    2007, 2(2): 184-192. https://doi.org/10.1007/s11465-007-0031-9
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    The emergency design of mechanical products or equipment (such as a satellite) is significant for disaster relief when the natural disasters occur. Most of us are unaware about the little information that is available in literature about emergency designs. Against the background of the preliminary scheme design of satellite payloads, emergency design was studied in the case of natural disasters. We presented some definitions about emergency design. Then, we proposed the basic ideas of how to realize the emergency design. These ideas were inspired by two aspects: 1) the evolutionary algorithms, the agent, the human-computer cooperation, and the collaborative design theory; 2) the emergency behaviors in ant colonies. Following the ideas, first we constructed the human computer cooperation agents (hereinafter called the HC-Agents) that combine the human intelligence with evolutionary algorithms. These HC-Agents had specific features like the division of labor in the ant colony. Second, we developed the multiagents cooperative design system on the basis of a hybrid P2P (peer-to-peer) model. Therefore, the emergency design system has shown some capabilities, such as anti-interference, adaptation, and rapid response.
  • A measurement system for thin elastohydrodynamic lubrication films
    WANG Xuefeng, GUO Feng, YANG Peiran
    2007, 2(2): 193-196. https://doi.org/10.1007/s11465-007-0032-8
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    An elastohydrodynamic lubrication (EHL) film measurement system using multi-beam interferometry is introduced in this paper. The measurement principle and the instrumentation are discussed. A simple and efficient method is suggested to obtain the fringe order of measured points. It is demonstrated that the presented measurement system can provide continuous measurement of lubricating films from nano to micro scales at a nano-level resolution, and can be used to investigate ultra-thin EHL films and tiny variations in EHL films.
  • An autonomous miniature wheeled robot based on visual feedback control
    CHEN Haichu
    2007, 2(2): 197-200. https://doi.org/10.1007/s11465-007-0033-7
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    Using two micro-motors, a novel omni-direction miniature wheeled robot is designed on the basis of the bi-corner driving principle. The robot takes advantage of the Bluetooth technology to wirelessly transmit data at a short distance. Its position and omni-direction motion are precise. A Charge Coupled Device (CCD) camera is used for measuring and for visual navi gation. A control system is developed. The precision of the position is 0.5 mm, the resolution is about 0.05 mm, and the maximum velocity is about 52 mm/s. The visual navigation and control system allow the robot to navigate and track the target and to accomplish autonomous locomotion.
  • The role delegation authorization model of a computer-supported cooperative design system
    XU Hongxue, LIU Yongxian, SHENG Zhongqi, GUO Xiuying
    2007, 2(2): 201-204. https://doi.org/10.1007/s11465-007-0034-6
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    According to the specific characteristics of a computer-supported cooperative design (CSCD) system, the characteristics of role delegation authorization (RDA) are analyzed and deduced, and a set of fitful status is arrived at. Because of the diversified characteristics of RDA features in different systems, the RDA model has multi-varying status. On the basis of the basic model of role-based access control (RBAC), some basic characteristics of RDA are summed up. Then, according to the specific characteristics of CSCD system, the characteristics of RDA are recombined to develop a RDA model that is suitable for the CSCD system. It is different from the conventional role authorization models of RBAC, that is, it adopts the decentralized authorization management instead of the centralized one in CSCD system, which makes the management more flexible. This model is verified through a specific case of CSCD system.
  • Integration of microsensor for microsurgery robot’s end-effector
    HU Yida, LI Dazhai, YANG Yang, SUN Xuguang
    2007, 2(2): 205-209. https://doi.org/10.1007/s11465-007-0035-5
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    To enhance the effect of robotic microsurgery, the microsensors are integrated on the robot s end-effector. On the basis of the requirements presented for the integration design, measuring mechanism for the robotic end trephine s force and cutting depth are studied. Force microsensor and position microsensor are used to measure surgical information of the force and depth. Measuring mechanism was achieved by means of linear sliding bearing and differential measuring structure. The sensor data board was developed. With the power spectral estimation of sensor data, two digital filtering methods are proposed, to help eliminate the interference to the original microsensor signal. They are the filtering method of lowpass-bandstop serial structure suitable for a PC, and a shift average filtering algorithm suitable for the sensor data board, respectively. The experimental results show that the integration of microsensors for microsurgery robot s end-effector can satisfy the design requirements, and the robotic end trephine can accurately fulfill the surgical task of corneal cutting.
  • Study on affecting factors of collaborative product development based on collaboration hierarchy model
    ZHANG Xiaodong, LI Yingzi, ZHANG Zhiqiang
    2007, 2(2): 210-213. https://doi.org/10.1007/s11465-007-0036-4
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    Aiming at the levels of collaborative degree in web-based product development, a collaboration hierarchy model of this product development is developed in this paper. Based on the model, the affecting factors on collaboration levels are analyzed systematically from many aspects, such as technology, organization and business. A gap analysis method is studied in detail, and is applied in a real project. The application shows that it can solve the diverse problems of collaborative product development effectively, and help enterprises find out the critical factors that affect the collaboration.
  • Reliability analysis of kinematic accuracy for the elastic slider-crank mechanism
    TUO Yaofei, CHEN Jianjun, ZHANG Chijiang, CHEN Yongqin
    2007, 2(2): 214-217. https://doi.org/10.1007/s11465-007-0037-3
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    This paper deals with the static and dynamic output kinematic accuracy of a group of elastic slider-crank mechanisms with the same design parameters by taking the bar length, the joint-gaps, the mass density, and the sectional and the physical parameters as random variables. According to the principle of linear pile-up of small displacement, the static and dynamic output kinematic errors are synthesized, and the reliability model of the kinematic accuracy of the mechanism is built. Through an example, a study of the influencing factors on the reliability of the output kinematic accuracy of the mechanism is made. The results obtained reveal the following facts: with the increase of the crank s rotating speed, the dynamic elastic deformation of the mechanism becomes the principal factor that greatly affects the reliability of the output kinematic accuracy of the mechanism.
  • Laser vision sensing based on adaptive welding for aluminum alloy
    CHEN Zhixiang, SONG Yonglun, ZHANG Jun, ZHANG Wanchun, JIANG Li, XIA Xuxin
    2007, 2(2): 218-223. https://doi.org/10.1007/s11465-007-0038-2
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    A laser vision sensing based on the adaptive tungsten inert gas (TIG) welding system for large-scale aluminum alloy components was established to fit various weld groove conditions. A new type of laser vision sensor was used to precisely measure the weld groove. The joint geometry data, such as the bevel angle, the gap, the area, and the mismatch, etc., aided in assembling large-scale aerospace components before welding. They were also applied for automatic seam tracking, such as automatic torch transverse alignment and torch height adjustment in welding. An adaptive welding process was realized by automatically adjusting the wire feeding speed and the welding current according to the groove conditions. The process results in a good weld formation and high welding quality, which meet the requirements of related standards.
  • A novel soft-switching twin arc pulse MAG welding inverter
    WANG Zhenmin, XUE Jiaxiang, WANG Fuguang, HUANG Shisheng
    2007, 2(2): 224-227. https://doi.org/10.1007/s11465-007-0039-1
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    The high-speed double wire pulse metal gas arc (MAG) welding process possesses advantages of automation and high efficiency and quality. Thus, it attracts much more attention nowadays. To meet the requirements of the double wire pulse MAG welding process, a novel double wire pulse MAG welding inverter integrated with technologies, such as soft-switching, double closed loop control, and synchronic control, is produced. A complete performance test was done for the pulsed MAG welding power supply by using a computer testing platform. The results of the experiment indicate that the novel welding inverter has an excellent performance both in the dynamic and the static characteristics. Also, the synchronic control between the master inverter and the slave inverter is reliable.
  • Image automatic mosaics based on contour phase correlation
    ZHANG Jing, HU Zhiping, OU Zongying, LIU Zhitai
    2007, 2(2): 228-234. https://doi.org/10.1007/s11465-007-0040-8
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    The image planar mosaics is studied, and an image automatic mosaics algorithm on the basis of contour phase correlation is proposed in this paper. To begin with, by taking into account mere translations and rotations between images, a contour phase correlation algorithm is used to realize the preliminary alignments of images, and the initial projective transformation matrices are obtained. Then, an optimization algorithm is used to optimize the initial projective transformation matrices, and complete the precise image mosaics. The contour phase correlation is an improvement on the conventional phase correlation in two aspects: First, the contours of images are extracted, and the phase correlation is applied to the contours of images instead of the whole original images; Second, when there are multiple peak values approximate to the maximum peak value in the ? function array, their corresponding translations can be regarded as candidate translations and calculated separately, and the best translation can be determined by the optimization of conformability of two images in the overlapping area. The running results show that the proposed algorithm can consistently yield high-quality mosaics, even in the cases of poor or differential lighting conditions, existences of minor rotations, and other complicated displacements between images.
  • Inverse kinematics analysis and numerical control experiment for PRS-XY style hybrid machining tool
    JIA Dongyong, ZHANG Jianmin, SUN Hongchang, NIU Zhigang
    2007, 2(2): 235-238. https://doi.org/10.1007/s11465-007-0041-7
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    This paper analyzed the inverse kinematics for the new Parallel rotate slider-X Y axes (PRS-XY) style hybrid machining tool and educed the five axes linkage inverse kinematics transform formula on the basis of the coordinates of the X, Y, Z, A and B virtual axes. The program for the PRS-XY style hybrid machining tool in accordance with the program manner for the common numerical control (NC) machine tool was made. The results of the experiments prove that the inverse kinematics transform formula is correct.
  • Non-electric welding and its application on equipment under emergency conditions
    HU Junzhi, HU Chunhua, MA Shining, XIN Wentong
    2007, 2(2): 239-242. https://doi.org/10.1007/s11465-007-0042-6
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    This paper introduces the working principle, characteristics, development, welding techniques, and applications of non-electric welding. We analyzed the microstructure of the welding bead and the tensile strength of the non-electric welded joints. The results indicate that the welding technique is simple, the performance of the welding line is excellent, and that the application is broad. Therefore, non-electric welding shows favorable application value and potential prospect.
  • Research on constraint-based virtual assembly technologies
    YANG Rundang, WU Dianliang, FAN Xiumin, YAN Juanqi
    2007, 2(2): 243-249. https://doi.org/10.1007/s11465-007-0043-5
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    To realize a constraint-based virtual assembly operation, the unified representations of the assembly constraint, the equivalent relation between the constraint and the degree of freedom (DOF), and the movement DOF reduction in a virtual environment are proposed. Several algorithms about the constraint treatment are submitted. First, the automatic recognition algorithm based on the assembly relation is used to determine the position and orientation relation between two geometry elements of constraint whether they meet the given errors. Second, to satisfy the new constraint, according to the positing solving algorithm, the position and orientation of an active part are modified with minimal adjustment after the part has satisfied the affirmed constraints. Finally, the algorithm of movement navigation based on the generalized coordinate system is put forward, and the part movement is guided. These algorithms have been applied to the integrated virtual assembly environment (IVAE) system. Experiments have indicated that these algorithms have well supported constraint treatments in the IVAE and realized the closer combination of the virtual and the real assembly processes.