共查询到20条相似文献,搜索用时 546 毫秒
1.
NON-CONTACT MEASUREMENT OF SCULPTURED SURFACE OF ROTATION 总被引:2,自引:0,他引:2
Zhang GuoxiongLiu ShuguiQiu ZurongYu FushengNaYonglinLeng ChanglinState Key Laboratory of PrecisionMeasuring Technology Instruments Tianjin University Tianjin China 《机械工程学报(英文版)》2004,17(4):571-574
A method for measuring the sculptured surface of rotation by using coordinate measuring machine (CMM) and rotary table is proposed. The measurement is realized during the continuous rotation of the workpiece mounted on the rotary table while the probe moves along the generatrix of the surface step by step. This method possesses lots of advantages such as simplicity of probe motion, high reliability and efficiency. Some key techniques including calibration of the effective radius of the probing system, determination of the position of axis of rotation, auto-centering of the workpiece, data processing algorithm, are discussed. Approaches for determining the coordinates on measured surface, establishing workpiece coordinate system and surface fitting are presented in detail. The method can be used with contact or non-contact probes. Some fragile ceramic and plaster parts are measured by using the system consisting of a CMM, rotary table, motorized head and non-contact laser triangulation probe. The measurin 相似文献
2.
Li Yanwen Huang ZhenRobotics research Center Yanshan University Qinhuangdao China 《机械工程学报(英文版)》2003,16(3):325-328
The general-linear-complex singularity of Stewart mechanism is a very important problem in the parallel manipulator. Its general regularity is not found yet during the past two decades. StOnge and Gosselin pointed out that the singularity locus of the Stewart mechanism at some given orienb-tions of the moving platform should be polynomial expressions with varied degrees in 2000, but they didn't formulate the expression. Based on the kinematics singularity principle and the geometry cond-tion proposed by Huang Zhen in 1999, firstly the singularity equation in degree two is derived. It is a hyperbola when the orientation of the moving platform is given. This result is also proved using screw theory. Then some singularity surfaces are gotten in three-dimensional space. This result is of impcr-tant significance. 相似文献
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Zhang LiZhang YufengHuo LixingSchool of Material Scienceand Engineering Tianjin University Tianjin China 《机械工程学报(英文版)》2004,17(3):346-348
To investigate the effect of dynamic loading on fracture behavior of welded joints of structural steel Q23SB and 16Mn in common use and compare the earthquake resistances of the two kinds of materials, dynamic tension and fracture toughness tests are carried out at room temperature. On the basis of the tests, the stress-strain fields near the crack tip of the compact specimens are analyzed by three-dimensional finite element model. The test results and finite element analysis results show that, the fracture toughness of welds and base metal of 16Mn steel increases with the increment of loading rate. Compared with 16Mn steel, Q235B steel is more sensitive to dynamic loading. The fracture toughness of welds of Q235B is comparatively low under static loading and dynamic loading at room temperature. Compared with the static loading, the fracture toughness of Q235B parent metal under dynamic loading decreases by about four times. Therefore, it can be concluded that compared with 16Mn steel, the earthquake re 相似文献
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THEORY OF HELICOID OF SPHERICAL HOB 总被引:1,自引:0,他引:1
THEORYOFHELICOIDOFSPHERICALHOBTHEORYOFHELICOIDOFSPHERICALHOBCuiyunqi;HuZhanqi(YanshanUniversity)AbstractThemechanismofspheric... 相似文献
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SIMULATIONOFROLL-FORMINGPROCESSESOFWELDEDPIPEMULATIONOFROLL-FORMINGPROCESSESOFWELDEDPIPEHuaJiang;(NanchangUniversity)ManabuKi... 相似文献
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Yang Fulun Yu Junyi Hong LiJinlin University of Technology Changchun University 《机械工程学报(英文版)》1995,(2)
REGULARITYOFVIBRATIONRESPONSEOFMECHANICALSYSTEMUNDERAFFECTOFVARI-FREQUENCYEXCITINGFORCEREGULARITYOFVIBRATIONRESPONSEOFMECHANI... 相似文献
7.
On the application of an electric field, the mechanical properties of ER(Electro-rheological) fluid are very complex. The damping force of ER fluid is linear without electric field and is nonlinear when an electric field is applied. By increasing the strength of the electric field, the behavior of ER fluid changes from linear viscous to nonlinear viscoelastic-plastic. External electric fluid changes natural behavior of system with ER fluid besides the mechanical properties of ER fluid. The affect of ER fluid on the stiffness of nonlinear vibration system with ER dampers is analyzed by iterative perturbation method. The results show that the stiffness of structure would be increased with growing of the strength of the electric field. 相似文献
8.
MACHININGMECHANISMOFMIRROR-LIKESURFACEOFADVANCEDCERAMICSMACHININGMECHANISMOFMIRROR-LIKESURFACEOFADVANCEDCERAMICSWangZhongqi;C... 相似文献
9.
Liu YinshuiNie SonglinZhu YuquanHe XiaofengLi ZhuangyunSchool of Mechanical Scienceand Engineering Huazhong University of Scienceand Technology Wuhan China 《机械工程学报(英文版)》2004,17(3):450-453
Experimental investigations are made on the effects of operating conditions on the flow characteristics of throttle when tap water is used as the working media. The researched throttles include cone poppet valve, ball valve, disc valve and dumping orifice. Operating condition includes poppet lift, working media, back pressure, medium temperature, etc. Because the vapourous pressure of water is much higher than that of oil, cavitation is easier to occur in water hydraulic elements and systems, so the effects of operating conditions on the cavitation characteristics of throttle are also researched. 相似文献
10.
ANALYSIS OF METHOD FOR DETERMINING AZIMUTH OF PRINCIPAL AXIS OF INERTIA BASED ON DYNAMIC BALANCE MEASUREMENT 总被引:1,自引:0,他引:1
ZHAO Jun GUAM Yingzi Ql Naiming College of Astronautics Harbin Institute of Technology Harbin China 《机械工程学报(英文版)》2006,19(4):530-533
The dynamic balance quality of a rotating object is an important factor to maintain the stability and accuracy for motion. The azimuth of the principal axis of inertia is a major sign of dynamic balance. A usual method is measuring moment of inertia matrix relative to some base coordinates on a rotary inertia machine so as to calculate the azimuth of principal axis of inertia. By using the measured unbalance results on the two trimmed planes on a vertical hard bearing double-plane dynamic balancing machine, the dimension and direction of couple unbalance can be found. An azimuth angle formula for the principal axis of inertia is derived and is solved by using unbalance quantities. The experiments indicate that method based on dynamic balancing measurement is proved rational and effective and has a fine precision. 相似文献
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In this paper, we present an experimental set-up and procedure to accurately measure the bearing characteristics of any single Degree of Freedom (DoF) straight-line flexure mechanism. Bearing characteristics include stiffness in the bearing and motion directions, and error motions in the bearing directions. In particular, we present this characterization for the traditional paired double parallelogram (DP-DP) flexure and its recently-reported improved variation, the clamped paired double parallelogram (C-DP-DP) flexure. Of particular interest is the bearing direction stiffness and its variation with motion direction displacement. While the bearing stiffness for both mechanisms has been extensively predicted via analysis and its consequences have been observed in experiments, its direct measurement poses several challenges and is not found in the literature. This paper presents an experimental set-up that is reconfigurable to accommodate both the above two flexures, comprises a novel virtual pulley concept, and employs carefully selected ground mounting and sensor locations, among other features that enable the desired measurements. The experimental results agree well with analytical predictions and generate insight into the importance of ground mounting, finite compliance of mechanism features that are generally assumed to be rigid, and manufacturing tolerances. 相似文献
13.
PRINCIPLES AND PARAMETER DESIGN FOR AC-DC THREE-DEGREE FREEDOM HYBRID MAGNETIC BEARINGS 总被引:4,自引:0,他引:4
ZHU Huangqiu XIE Zhiyi ZHU Dehong School of Electrical Information Engineering Jiangsu University Zhenjiang China 《机械工程学报(英文版)》2006,19(4):534-539
To simplify the mechanical structure, decrease the overall system size of the 3-degree freedom axial-radial magnetic bearings and reduce the manufacturing costs as well as operating costs, an innovated AC-DC 3-degree freedom hybrid magnetic bearing is proposed, which is driven by a DC amplifier in axial direction and a 3-phase power converter in radial directions respectively, and the axial and radial bias magnetic fluxes are provided with a common radial polarized permanent magnet ring. The principle producing magnetic suspension forces is introduced. By using equivalent magnetic circuit method, the calculation formulas of magnetic suspension forces and the mathematics models of the system are deduced. Nonlinearities of suspension forces and cross coupling between different degree freedoms are studied further by calculating the suspension forces at different displacements and control currents to validate the feasibility of the mathematics model. Then based on the mathematics models of the bearing, a control method of this novel bearing is designed. Lastly, the methods on parameter design and calculations of the bearing are presented, and an applicable prototype is simulated to analyze the magnetic path by using finite element analysis. The theory analysis and simulation results have shown that this magnetic bearing incorporates the merits of 3-phase AC drive, permanent magnet flux biased and axial-radial combined control, and reduces overall system size and has higher efficiency and lower cost. This innovated magnetic bearing has a wide application in super-speed and super-precision numerical control machine tools, bearingless motors, high-speed flywheels, satellites, etc. 相似文献
14.
基于曲线柔性单元的新型大变形柔性铰链 总被引:10,自引:1,他引:10
曲线薄板柔性单元与传统的缺口式柔性单元相比,受载荷时在功能方向上更容易产生大变形.基于此,将曲线薄板柔性单元在平面空间中以一点为圆心,进行均匀阵列组合得到一种新型的环形柔性铰链--分布式叶片形转动柔性铰链.为了对新型柔性铰链进行性能分析,建立铰链的数学模型.鉴于铰链结构复杂,要得到精确模型十分困难,因此对模型进行简化,采用主运动单元伪刚体法建立新型柔性铰链数学模型,并分析新型柔性铰链受纯扭矩载荷时的变形情况.计算得到的结果与非线性有限元分析结果十分接近,证明了所建伪刚体模型的正确性.同时计算结果也表明分布式叶片形转动柔性铰链能够提供较大的转动行程,是一种新型的大变性转动柔性铰链. 相似文献
15.
A flexure hinge is a major component in designing compliant mechanisms that o ers unique possibilities in a wide range of application fields in which high positioning accuracy is required. Although various flexure hinges with di erent configurations have been successively proposed, they are often designed based on designers' experiences and inspirations. This study presents a systematic method for topological optimization of flexure hinges by using the level set method. Optimization formulations are developed by considering the functional requirements and geometrical constraints of flexure hinges. The functional requirements are first constructed by maximizing the compliance in the desired direction while minimizing the compliances in the other directions. The weighting sum method is used to construct an objective function in which a self-adjust method is used to set the weighting factors. A constraint on the symmetry of the obtained configuration is developed. Several numerical examples are presented to demonstrate the validity of the proposed method. The obtained results reveal that the design of a flexure hinge starting from the topology level can yield more choices for compliant mechanism design and obtain better designs that achieve higher performance. 相似文献
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The thin-walled tube flexure(TWTF) hinges have important potential application value in the deployment mechanisms of satellite and solar array, but the optimal design of the TWTF hinges haven't been completely solved, which restricts their applications. An optimal design method for the qusai-static folding and deploying of TWTF hinges with double slots is presented based on the response surface theory. Firstly, the full factorial method is employed to design of the experiments. Then, the finite element models of the TWTF hinges with double slots are constructed to simulate the qusai-static folding and deploying non-linear analysis. What's more, the mathematical model of the TWTF flexure hinge quasi-static folding and deploying properties are derived by the response surface method. Considering of small mass and high stability, the peak moment of quasi-static folding and deploying as well as the lightless are set as the objectives to get the optimal performances. The relative errors of the objectives between the optimal design results and the FE analysis results are less than 7%, which demonstrates the precision of the surrogate models. Lastly, the parameter study shows that both the slots length and the slots width both have significant effects to the peak moment of quasi-static folding and deploying of TWTF hinges with double slots. However, the maximum Mises stress of quasi-static folding is more sensitive to the slots length than the slots width. The proposed research can be applied to optimize other thin-walled flexure hinges under quasi-static folding and deploying, which is of great importance to design of flexure hinges with high stability and low stress. 相似文献
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Dimensionless design graphs for flexure elements and a comparison between three flexure elements 总被引:1,自引:0,他引:1
Wouter O. Schotborgh Frans G. M. Kokkeler Hans Tragter Fred J. A. M. van Houten 《Precision Engineering》2005,29(1):1348
This paper presents dimensionless design graphs for three types of flexure elements, based on finite element analysis. Using these graphs as a design tool, a designer can determine the optimal geometry, based on the stiffness and rotation demands of a flexure element. An example is given using the beam flexure hinge.Between the analyzed flexure hinges, a comparison is made on basis of equal hinge functionality: rotation. The result describes the maximum stiffness properties from different hinges in identical situations. A beam flexure element is preferred over a circular flexure hinge for stiffness demands in a single direction, while a cross flexure element enables medium stiffness in two perpendicular directions. 相似文献