• Title/Summary/Keyword: Optimum vibration angle

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Optimum Vibration Angle for Transporting Granular Materials on Linear Conveyors

  • Keraita, James Nyambega
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.2
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    • pp.3-7
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    • 2008
  • Vibratory conveyors are widely used in industry to transport granular materials and products. A theoretical point mass model for vibratory conveying was studied. The results agreed well with experimental observations. The model theory included the resting, sliding and flight states of the material. Each state was considered separately when determining the equations of motion. For the coefficients of restitution, values of zero for the normal component and 0.8 for the tangential component were found to be appropriate for modeling the collisions of the granular particles with the conveying surface. The vibration angle had a large influence on the mode and rate of transport. There was an optimum vibration angle for a given set of conditions. The optimum vibration angle decreased and was better defined as the coefficient of friction increased. The results suggest the existence of an optimum dimensionless track acceleration (throw number), which does not support general industrial practice in which the track acceleration is limited when the feed cycle becomes erratic and unstable.

Study of the non-linearity of cable damper to enhance damping performance of stay cable (사장교 케이블의 감쇠성능 향상을 위한 댐퍼의 비선형성 연구)

  • Seo, Ju-Won;Koh, Hyun-Moo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.147-156
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    • 2007
  • This study offers a design procedure of optimum cable damper for multi-mode vibration control with nonlinear damper and also investigate the relation between mode and amplitude dependency. The proposed multi-mode damping index, which is defined as a energy loss ratio of cable potential, is a main component of optimization problem of optimum nonlinear damper. In order to include the amplitude dependency of nonlinear damper, it is assumed to exist three kinds of multi-mode patterns such as ambient vibration, support excitation and rain-win induced vibration. The optimum damper exponent depends on amplitude patterns. In case of ambient vibration, optimum factor is less than 0.5. In case of support excitation or rain-wind induced vibration is between 0.5 and 1.0. In this study, the effects of cable sag and inclination angle are included in the asymptotic design equation of damped cable structures.

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Optimum Design of the Laminated Composite Sandwich Plate Structure of Truss Core considering Vibration Characteristics (복합적층 트러스 코어형 샌드위치 판구조물의 진동특성을 고려한 최적설계)

  • Jung, Suok-Mo;Hong, Do-Kwan;Ahn, Chan-Woo
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.703-709
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    • 2001
  • In this paper, we analyzed the laminated composite sandwich plate structure of truss core with changing values of the designing parameters. As a result, in designing parameters of that, the more height and thickness of the laminated composite plate's core, the more increase of natural frequency. In this type of structure, in the case of applying core of the laminated composite plate and antisymmetric stacking, natural frequency has high value and we calculated the optimum angle-ply making natural frequency maximum. Natural frequency of CFRP is higher than that of GFRP. Both are materials of the laminated composite plate. The mode shapes are various along with the angle-ply of the laminated composite plate.

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Optimum Design of the Laminated Composite Sandwich Plate Structure of Honeycomb Core considering Vibration Characteristics (복합적층 하니콤 코어형 샌드위치 판무구조물의 진동특성을 고려한 최적설계)

  • Seo, J.;Hong, D. K.;Ahn, C. W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.710-715
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    • 1997
  • This paper deals with the analysis of the optimum value of honeycomb core considering variable design parameter. As thickness and height of core rises in design parameter, natural frequency of laminated composite plate increases. The angle-phy has the maximum value when the plate of honeycomb core join to opposite direction. This paper shows that the natural frequency of CFRP was higher than that of GFRP and mode shapes were various at angle-ply.

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Development of Vibration Motor Using Coreless Permanent Magnet DC Motor (무철심 영구자석 직류 모터를 이용한 진동자 개발)

  • Hwang, Sang-Moon;Chung, Shi-Uk
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.7
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    • pp.15-23
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    • 1999
  • With a remarkable expansion of communication industry, a pager or a cellular phone becomes a necessary communication device in modern society. However, a paging signal by a buzzer is often acted as an unpleasant noise in some places, thus necessitating a paging signal by a vibration motor. In this paper, a simpler type of a vibration motor, a coreless permanent magnet(PM) DC motor, is considered to substitute for the conventional vibration motors. Using an analytical method, electromagnetic field and operating torque were calculated for the given inner and outer PM type motors, and the results were confirmed by FEM analysis. As design parameters, number of PM poles, PM radial thickness, coil arc angle and number of winding stacks were chosen for sensitivity analysis. It shows that coil arc angle is the most important design parameter to increase the motor performance, without giving an adverse effect on motor weight, size and manufacturing cost. Based on the analysis of the outer PM type motor, an outer square PM type motor is proposed as the final design. Compared to the outer PM type, outer square type provides more flexibility to attach to the small size cellular phones. With the optimum design of square outer PM DC motor, it can successfully substitute the conventional types with less expensive manufacturing cost. better performance and smaller necessary space.

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Design of Low Noise Axial Flow Fan Using Specific Sound Presssure Level (비소음 측정을 이용한 저소음 축류홴 설계)

  • 김창준;이동익
    • Journal of KSNVE
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    • v.10 no.5
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    • pp.873-879
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    • 2000
  • Experimental investigation was conducted to study the effects of pitch angle maximum camber on the performance and noise of an axial-flow fan used in outdoor-unit of air -conditioner. For this study the axial-flow fan whose pitch angle can be varied was made and the Specific sound Pressure Level and other coefficients were measured using the anechoic fan tester. It is found that pitch angle affects more severly than the maximum camber on the fan performance. On the while the maximum camber affects much on the specific sound power level. Present results show that it is important to choose the optimum pitch angle and maximum camber to design the high-performance and low-noise axial-flow fan and specific noise measured in the anechoic fan tester can be sued effectively for the design of low-noise fan.

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Modeling and Dynamic Analysis of a Front Loaded Washing Machine with Ball Type Automatic Balancer (볼 자동균형장치를 채용한 드럼세탁기의 모델링 및 동적 거동 해석)

  • 이준영;조성오;김태식;박윤서
    • Journal of KSNVE
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    • v.8 no.4
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    • pp.670-682
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    • 1998
  • Ball type automatic balancer is used to reduce the vibration caused by unbalance of rotor. In this study, A analytic modeling of a front loaded washing machine with ball type automatic balancer has been suggested theoretically and ADAMS has been used to analyze the dynamic characteristics of automatic balancer. It is found from simulation and experimental results that the automatic balancer suppress the steady state vibration of washing machine effectively. The test results match with the simulation results of ADAMS, thereby the dynamic model of ADAMS can be used as virtual prototype to predict the vibration characteristics which could be changed by the modification of design variableand can reduce the design cycle sharphy. To maximize the balancing effect of automatic balancer, the friction between balls and race and the deviation between geometric center and rotation center of drum need to be minimized and the optimum design for the stiffness of flange shaft and the angular acceleration of drum should be achieved.

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Optimum Geometric and Electrical Parameter for minimization Torque Ripple of Switched Reluctance Motor (스위치드 릴럭턴스 전동기의 토오크 리플 저감을 위한 기하학적인 파라미터와 전기적인 파라미터의 최적화)

  • Jung, S.I.;Choi, J.H.;Kim, Y.H.;Kim, S.;Lee, J.;Ju, M.S.;Choi, D.H.
    • Proceedings of the KIEE Conference
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    • 2001.07b
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    • pp.608-610
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    • 2001
  • In this paper, 6/4 Switched Reluctance Motor(SRM) which has simple structure and little switching element is selected basic analysis model. In order to reduce torque ripple causing noise and vibration, we execute optimization of geometric parameters (stator and rotor pole arc) and electrical parameters (turn-on angle and turn-of angle) by means of combining Fletcher-Reeves's Conjugate Directions and Finite Element Method (FEM) considering driving circuits. When considering the switching condition according to inductance profile, torque characteristics is influenced by geometric and electrical parameters importantly. The pole arc and switching angle of the optimum can also obtain the low torque ripple without high currents.

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Study on Noise Reduction by Optimizations of In-line Duct Flow (덕트의 유로 최적화를 통한 소음저감 연구)

  • Han, Jae-Oh;Lee, Soo-Young;Mo, Jin-Yong;Lee, Jai-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.803-808
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    • 2006
  • This paper was a study about noise reduction through flow stabilization in duel using experimental method and numerical analysis at the same time. To determine the fan's type three kinds of fans(axial fan, centrifugal fan, and axial fan with centrifugal type) was examined to investigate the suitability for duct. As a result, under the equal number of rotation 2000 RPM, performance of an axial fan with centrifugal type was the most superior by 55dBA at 4.3CMM among other fans. After this, analyzed the results of the numerical analysis to find out the optimum design of pitch angle such as $0^{\circ},\;10^{\circ},\;15^{\circ}\;and\;20^{\circ}$. The intensity of turbulence was low when pitch angle was $15^{\circ}$ and air volume became peak by 5.08 CMM. It was observed that axis component of velocity increased gradually when pitch angle increased from $0^{\circ}\;to\;20^{\circ}$. Finally, designed the shapes of D/S(Down Stream) in duct that agreed inlet angle($\delta$) of stationary blades with pitch angle($\beta$) of axial fan with centrifugal type and derived flow to duct medial, and changed the shape of motor-mount to reduce occurance of unstable vortex in tip of impeller, and embodied noise reduction and improvement of air flow rate through flow stabilization.

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Analysis of Force Characteristic in Switched Reluctance Motor According to Electric (전기적인 파라메터 변화에 따른 스위치드 릴럭턴스 전동기의 힘특성 해석)

  • Chun, Yon-Do;Ree, Cheol-Jick;Lee, Taeck-Kie;Lee, Ju
    • Proceedings of the KIEE Conference
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    • 2001.10a
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    • pp.122-124
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    • 2001
  • In this paper, the influence of electrical parameters such as the turn-on and turn-off angle on the torque and force characteristics is investigated for the reduction of the torque ripple which is main source of vibration and noise in switched reluctance motor (SRM). The four different types of the turn-on angle are set to the section of rising inductance profile respectively. The optimum turn-on angle is proposed for the acquisition of the flat current shape minimizing the torque ripple. 2D finite element method (FEM) considering the iron saturation and the actual switching circuit of the SRM drive is applied for the dynamic analysis. The simulation results of phase current and torque are also compared to the experimental results.

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