Wang T.-Y.,Shenyang Institute of Engineering |
Wang F.-X.,Shenyang University of Technology
Gongcheng Lixue/Engineering Mechanics | Year: 2012
For a high-speed motor unit, it is very important to accurately predict dynamic characteristics of the rotor for high speed performance at the design stage so as to minimize the likelihood of failure. Finite element (FE) analysis and experimental measurements are used to calculate the critical speeds, and the modes of multi-span shafting coupled by flexible coupling, and the axial, radial and torsional stiffness of elastic coupling are simulated using the spring element of FE analysis tools. The influence of coupling stiffness and leading design parameters of coupling are analyzed. The results show that the critical speeds and mode shapes of shafting are different from a single rotor, and can be adjusted by changing the stiffness and structure of coupling in order that the shafting has sound dynamic properties.
Wang S.,Shenyang University of Technology
Mathematical Problems in Engineering | Year: 2013
A mechanical component may fail in many modes that are usually not independent. There is generally not a joint probability density function to describe these correlated failure modes. Thus, it is difficult to compute the reliability when considering the correlations between the failure modes. It is supposed that three or more failure modes arise synchronously to be a very small probability event. The relationship between ultimate state functions in different failure modes is established by utilizing linear regression method. A double integration model for reliability of mechanical components with dependent failure modes is built according to stress-strength interference model. In case of square, cube, or exponential relationship between two ultimate state functions, a linear transformation is made. An example of pin that may fail in shear fracture, bruise, or both is discussed. The reliability is compared with that obtained by usingMonte Carlomethod, which represents that the reliabilitymodel with dependent failure modes proposed is correct. Copyright © 2013 ShijieWang.
Wang F.,Shenyang University of Technology
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012
Permanent magnet (PM) machine has advantages of high power density, high efficiency and high reliability, and has been using widely in the wind power generation systems. However, the PM wind generators face the challenge of how to increase the ratio of performance to the cost due to the expensive rare earth PM material. In this paper, based on the comparative study on the feature and performance of PM generators for high speed, medium speed and low speed direct-driven wind power generation systems, the key design techniques of PM wind generators are explained. The influence of machine structure and combination of pole-slot number on the performance, the prevention of permanent magnet from demagnetizing, and the reasonable matching between generator and converter are analyzed. Besides, the development tendency of design and control technology of the PM wind power generators is discussed.
Li F.,Shenyang University of Technology |
Xie H.-L.,Northeastern University China
International Journal of Automation and Computing | Year: 2010
A visual servoing tracking controller is proposed based on the sliding mode control theory in order to achieve strong robustness against parameter variations and external disturbances. A sliding plane with time delay compensation is presented by the pre-estimate of states. To reduce the chattering of the sliding mode controller, a modified exponential reaching law and hyperbolic tangent function are applied to the design of visual controller and robot joint controller. Simulation results show that the visual servoing control scheme is robust and has good tracking performance. © 2010 Institute of Automation, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.
Liu G.-L.,Shenyang University of Technology
Wuli Xuebao/Acta Physica Sinica | Year: 2010
The electronic structure of Mg alloy was calculated with the recursion method. The result shows that the density of states of Mg in grain is similar to that on the surface of Mg alloy, but it is obviously different when O or O, H atoms exist on the surface of Mg alloys. This indicates Mg has similar properties whether in grain or on surface, but the properties of Mg change apparently after oxygen or hydrogen atom permeated in the surface layer of Mg alloy. Al, Y or La atom diffuses from grain to the surface and segregates there, because each the doped atom embedding energy of Al, Y or La atom on the surface is lower than that in grain. The affinity energy of Al-O, Y-O, La-O, Mg-O, Mg-O-H is negative, so they can form compound. Because the affinity energy of Mg-O-H is lower than that of Mg-O, Mg(OH)2 is more stable than MgO. In the early stage of oxidation, oxygen combined with Mg, Al, Y or La forming oxide. When Mg alloy is in corrosive medium, MgO reacts with H2O forming Mg(OH)2. Al2O3, (Y, La)2O3 and Mg(OH)2 can protect Mg alloys from corrosion and improve corrosion resistance. ©2010 Chin.Phys.Soc.