• Title/Summary/Keyword: mechanical couplings

Search Result 33, Processing Time 0.02 seconds

A Study on Polarization Mode Dispersion Properties of Concatenated Optical Fibers (이종 접합된 광섬유에 있어서 편광모드분산 특성에 관한 연구)

  • Lee, Cheong-Hak;Ryu, Boo-Hyung;Kim, Kee-Dae;Park, Dae-Hee
    • Proceedings of the KIEE Conference
    • /
    • 1999.07e
    • /
    • pp.2456-2458
    • /
    • 1999
  • The polarization mode dispersion (PMD) that restricts the transmission bandwidth was investigated in standard long single mode fiber which optimized at 1.3${\mu}m$. Although fiber has perfect circular symmetry, each optical fiber has different refractive index profiles. The investigation of PMD with random mode couplings were conducted in three kinds of fiber by the time-domain interferometric method. By using two manufacturing methods, MCVD(Modified Chemical Vapor Deposition) method and VAD(Vapor Phase Axial Deposition) method, the property of mechanical asymmetric lateral pressure, bending and twisting induced polarization mode dispersion were measured. The concatenated optical fibers were compared with other types.

  • PDF

Modeling of Belt-Pulley and Flexible Coupling Effects on Submarine Driven System Electrical Motors

  • Jafarboland, Mehrdad;Zadehbagheri, Mahmoud
    • Journal of Power Electronics
    • /
    • v.11 no.3
    • /
    • pp.319-326
    • /
    • 2011
  • Nowadays numerous research projects are being conducted in the field of electric motors. Non-modeling of flexible connections such as couplings and the belt-pulley do not show some real behaviors. With an increase in the number of connections and drive factors, these Non-modeled modes become more important. The coupling of two electric motors, instead of one motor, in submarine propeller force is an obvious example which shows that Non-modeled vibration modes caused by flexible connections can disturb controller operation and make undesirable vibrations in the submarine body. In this paper a dynamic model of flexible connections and a completed dynamic model of two different coupled electric models is presented. A robust controller for the completed model is also amended so that the two controlling targets of a desired speed adjustment and an appropriate load division between the two motors with sufficient accuracy are achieved.

Precise Braking Torque Control for Momentum Flywheels Based on a Singular Perturbation Analysis

  • Zhou, Xinxiu;Su, Dan
    • Journal of Power Electronics
    • /
    • v.17 no.4
    • /
    • pp.953-962
    • /
    • 2017
  • Momentum flywheels are widely applied for the generation of small and precise torque for the attitude control and inertial stabilization of satellites and space stations. Due to its inherited system nonlinearity, the tracking performance of the flywheel torque/speed in dynamic/plug braking operations is limited when a conventional controller is employed. To take advantage of the well-separated two-time-scale quantities of a flywheel driving system, the singular perturbation technique is adopted to improve the torque tracking performance. In addition, the composite control law, which combines slow- and fast- dynamic portions, is derived for flywheel driving systems. Furthermore, a novel control strategy for plug braking dynamics, which considers couplings between the Buck converter and the three-phase inverter load, is designed with easy implementation. Finally, experimental results are presented to demonstrate the correctness of the analysis and the superiority of the proposed methods.

A Vibration Rejection of Linear Feeder System with PMSM using Adaptive Notch Filter (적응형 노치 필터에 의한 PMSM을 이용한 선형 피드 시스템의 진동 억제)

  • Lee, Dong-Hee
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.11 no.3
    • /
    • pp.274-283
    • /
    • 2006
  • The Permanent Magnet Synchronous Motor(PMSM) drive systems with ball-screw, gear and timing-belt are widely used in industrial applications such as NC machine, machine tools, robots and factory automation. These systems have torsional vibration in torque transmission from servo motor to mechanical load due to the mechanical couplings. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the mechanical plant. This paper presents adaptive notch filter with auto searching function of vibration frequency to reject the mechanical vibration of linear feeder system with PMSM. The proposed adaptive notch filter can suppress the torque command signal of PMSM in the resonant bandwidth for reject the mechanical torsional vibration. However, the resonant frequency can vary with conditions of mechanical load system and coupling devices, adaptive notch filter can auto search the vibration frequency and suppress the vibration signal bandwidth. Computer simulation and experimental results shows the verification of the proposed adaptive notch filter in linear feeder system with PMSM.

Structural Analysis on Flange Coupling due to Change of Bolt Numbers (볼트 수 변경에 따른 플랜지 커플링에 대한 구조해석)

  • Han, Moonsik;Cho, Jaeung
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.12 no.5
    • /
    • pp.57-66
    • /
    • 2013
  • This study investigates structural and vibration analyses due to the change of bolt Numbers on models 1 and 2 of flange couplings connected with both sides of axis. As maximum equivalent stresses of models 1 and 2 are 122.05 and 102.3 MPa respectively by the basis of bolt, these stresses are within the allowable stress of this model and the safety of bolt design is verified. As maximum equivalent stresses of models 1 and 2 are 196.2 and 196.4 MPa respectively by the basis of body, these stresses are within the allowable stress of this model and the safety of body design is verified. Through natural frequency analysis, maximum displacements of model 1 and 2 are shown at the frequencies of 6565.1 and 6614.9 Hz respectively. Maximum displacements in cases of models 1 and 2 are shown at harmonic frequencies of 7760 and 7840 Hz at real loading conditions. By putting these study results together, the durability of vibration at model 2 with bolt numbers of 8 becomes better than model 1 with bolt numbers of 6. These study results can be effectively utilized with the design on flange coupling by anticipating and investigating prevention and durability against its damage.

Comparison of Simulation Models for Train Buffer Couplings (연결기용 완충기의 시뮬레이션 모델 비교)

  • Jang, Hyeon-Mog;Kim, Nam-Wook;Park, Yeong-Il
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.18 no.4
    • /
    • pp.107-114
    • /
    • 2010
  • Coupling systems for trains need more complicated buffer equipments than existing systems because the recent tendency of the regulations enforces trains to be safe for collisions even when the driving speed is higher than before. Using hydraulic buffer is an effective way to satisfy the requirement while it causes the increase of the cost for the coupling system. In this study, we introduce the methodology to build a simulation model for the hydraulic buffer, which could be installed into the coupling systems. In the simulation model of the hydraulic buffer, the reacting force is determined by both buffer stroke and speed whereas the elastic buffer model is designed by using only the buffer stroke in other studies. The simulation results with the advanced hydraulic buffer model shows that the simulating results can be close the real experimental results around 10%, and, if we considers friction forces, the simulation calculates the maximum force within 10% comparing to the experimental.

Modeling of time-varying stress in concrete under axial loading and sulfate attack

  • Yin, Guang-Ji;Zuo, Xiao-Bao;Tang, Yu-Juan;Ayinde, Olawale;Ding, Dong-Nan
    • Computers and Concrete
    • /
    • v.19 no.2
    • /
    • pp.143-152
    • /
    • 2017
  • This paper has numerically investigated the changes of loading-induced stress in concrete with the corrosion time in the sulfate-containing environment. Firstly, based on Fick's law and reaction kinetics, a diffusion-reaction equation of sulfate ion in concrete is proposed, and it is numerically solved to obtain the spatial and temporal distribution of sulfate ion concentration in concrete by the finite difference method. Secondly, by fitting the existed experimental data of concrete in sodium sulfate solutions, the chemical damage of concrete associated with sulfate ion concentration and corrosion time is quantitatively presented. Thirdly, depending on the plastic-damage mechanics, while considering the influence of sulfate attack on concrete properties, a simplified chemo-mechanical damage model, with stress-based plasticity and strain-driven damage, for concrete under axial loading and sulfate attack is determined by introducing the chemical damage degree. Finally, an axially compressed concrete prism immersed into the sodium sulfate solution is regarded as an object to investigate the time-varying stress in concrete subjected to the couplings of axial loading and sulfate attack.

Study on Design of Coupling Bolt for Shaft in Power Plant (발전용 축계 결합용 커플링 볼트 설계에 관한 연구)

  • Jeong, HoSeung;Son, ChangWoo;Cho, JongRae;Kim, Tae Hyung
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.5
    • /
    • pp.707-713
    • /
    • 2013
  • Coupling bolts have replaced conventional fitted bolts in applications where the operator's safety during assembly/disassembly is of concern or where the cost of process interruption is significant. Coupling bolts have been installed on rotating flange couplings in a wide range of marine and power applications worldwide. Their use has been approved by all leading international and national classification societies and regulatory bodies. A coupling bolt is a hydraulically tensioned fitted bolt that creates a stable and rigid link between coupling flanges and simplifies assembly and disassembly. We measure the bolt dimensions for reverse engineering and study the standard of assembly-load using a mechanical formula in order to localize a coupling bolt for a shaft in a power plant. We experimentally obtain the friction coefficient and confirm the condition of bolt sets through structure analysis. We show the variation of contact pressure for the shape parameter in order to consider the result when redesigning a bolt.

A STUDY ON NUMERICAL COUPLING BETWEEN MECHANICAL AND HYDRAULIC BEHAVIORS IN A GRANITE ROCK MASS SUBJECT TO HIGH-PRESSURE INJECTION

  • Jeong, Woo-Chang;Jai-Woo;Song, Jai-Woo
    • Water Engineering Research
    • /
    • v.2 no.2
    • /
    • pp.123-138
    • /
    • 2001
  • An injection experiment was carried ut to investigate the pressure domain within which hydromechanical coupling influences considerably the hydrologic behavior of a granite rock mass. The resulting database is used for testing a numerical model dedicated to the analysis of such hydromechanical interactions. These measurements were performed in an open hole section, isolated from shallower zones by a packer set at a depth of 275 m and extending down to 840 m. They consisted in a series of flow meter injection tests, at increasing injection rates. Field results showed that conductive fractures from a dynamic and interdependent network, that individual fracture zones could not be adequately modeled as independent systems, that new fluid intakes zones appeared when pore pressure exceeded the minimum principal stress magnitude in that well, and that pore pressures much larger than this minimum stress could be further supported by the circulated fractures. These characteristics give rise to the question of the influence of the morphology of the natural fracture network in a rock mass under anisotropic stress conditions on the effects of hydromechanical couplings.

  • PDF

Application of Nonlinear Feedback Control to an Articulated Manipulator (수직다관절 매니퓰레이터에 대한 비선형 되먹임제어의 응용)

  • Y.S. Baek;C.I. Yang;H.S. Aum
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.12 no.9
    • /
    • pp.104-114
    • /
    • 1995
  • Mathematical models of industrial robots or manipulators are composed of highly nonlinear equations with nonlinear couplings between the variables of motions. These nonlin- earities were not considered important in the first stage that the working speed of the manipulator was not so fast, but the effect of nonlinear forces has become serious, as the working speed has been increased. So more improvement of performance cannot be expected by the control of manipulator using approximate linearization. As an approach for solving these problems, there is a method that eliminates nonlinear theory, which makes possible cecoupling of coupling terms and arbitrary arranging of poles is briefly introduced in this study. When the theory is applied to design the control law, its feasibility is examined whether the reasonable control results are obtained by simulating position, velocity, torque and tracing trajectory. The relations between the coefficients of the linearized differential equations and the maximum error and torque for the prescribed trajectory are also examined. Finally, the method for selecting the values for getting the most rapid and precise response within maximum torque of each drive is suggested in the choice of coefficients of characteristic equations which are obtained as a result of the control.

  • PDF