• 제목/요약/키워드: Excitation angles

검색결과 63건 처리시간 0.024초

Optimal Excitation Angles of a Switched Reluctance Generator for Maximum Output Power

  • Thongprasri, Pairote;Kittiratsatcha, Supat
    • Journal of Electrical Engineering and Technology
    • /
    • 제9권5호
    • /
    • pp.1527-1536
    • /
    • 2014
  • This paper investigates the optimal values of turn-on and turn-off angles, and ratio of flux linkage at turn-off angle and peak phase current positions of optimal control for accomplishing maximum output power in an 8/6 Switched Reluctance Generator (8/6 SRG). Phase current waveform is analyzed to determine optimal excitation angles (optimal turn-on and turn-off angles) of the SRG for maximum output power which is applied from a nonlinear magnetization curve in terms of control variables (dc bus voltage, shaft speed, and excitation angles). The optimal excitation angles in single pulse mode of operation are proposed via the analytical model. Simulated and experimental results have verified the accuracy of the analytical model.

4행정 기관의 기진력 감소를 위한 크랭크 각 설계 (Crank Angles Design to Reduce the Excitation Forces in 4-stroke Diesel Engine)

  • 서영수;박정근;정의봉
    • 한국마린엔지니어링학회:학술대회논문집
    • /
    • 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
    • /
    • pp.108-114
    • /
    • 2000
  • The excitation forces from the periodical firing pressure in cylinder and the rotating crank mechanism cause lots of vibration problems in diesel engine. In this paper, the theoretical formulas for excitation forces are introduced and computational program for the optimization of crank angle is also developed to reduce the free moments in diesel engine. The computational results of 4-stroke in-line engine are applied to verify the reliability of the program.

  • PDF

고온에서 외부 가진력을 받는 회전하는 경사기능 박판 블레이드의 동적응답 해석 (Dynamic Response Analysis of Rotating Functionally Graded Thin-Walled Blades Exposed to Steady Temperature and External Excitation)

  • 오병영;나성수
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2004년도 추계학술대회
    • /
    • pp.643-648
    • /
    • 2004
  • This paper is dedicated to the thermoelastic modeling and dynamic response of the rotating blades made of functionally graded ceramic-metal based materials. The blades modeled as non-uniform thin walled beams fixed at the hub with various selected values of setting angles and pre-twisted angles. In this study, the blade is rotating with a constant angular velocity and exposed to a steady temperature field as well as external excitation. Moreover, the effect of the temperature gradient through the blade thickness is considered. Material properties are graded in the thickness direction of the blade according to the volume fraction power law distribution. The numerical results highlight the effects of the volume fraction, temperature gradient, taper ratio, setting angle and pre-twisted angle on the dynamic response of bending-bending coupled beam characteristics are provided for the case of a biconvex cross section and pertinent conclusions are outlined.

  • PDF

고온에서 외부 가진력을 받는 회전하는 경사기능 박간 블레이드의 동적응답 해석 (Dynamic Response Analysis of Rotating Functionally Graded Thin-Walled Blades Exposed to Steady High Temperature and External Excitation)

  • 나성수;오병영
    • 대한기계학회논문집A
    • /
    • 제29권7호
    • /
    • pp.976-982
    • /
    • 2005
  • This paper is dedicated to the thermoelastic modeling and dynamic response of the rotating blades made of functionally graded ceramic-metal based materials. The blades are modeled as non-uniform thin walled beams fixed at the hub with various selected values of setting angles and pre-twisted angles. In this study, the blade is rotating with a constant angular velocity and exposed to a steady temperature field as well as external excitation. Moreover, the effect of the temperature gradient through the blade thickness is considered. Material properties are graded in the thickness direction of the blade according to the volume fraction power law distribution. The numerical results highlight the effects of the volume fraction, temperature gradient, taper ratio, setting angle and pre-twisted angle on the dynamic response of bending-bending coupled beam characteristics and pertinent conclusions are outlined.

디젤엔진에서 기진력 감소를 위한 크랭크 각의 최적설계 (Optimal Design of Crank Angles for Reducing the Excitation Forces in a Diesel Engine)

  • 박정근;정의봉;서영수
    • 한국소음진동공학회논문집
    • /
    • 제12권2호
    • /
    • pp.108-115
    • /
    • 2002
  • The excitation forces from the periodical firing pressure in cylinder and the rotating crank mechanism cause lots of vibration problems in diesel engines. In this Paper. the computational program for predicting the excitation force is developed and applied to 4-stroke In-line engines. The crank angle is also optimized to reduce the first and second order moment produced by engines. Compared to the conventional uniform crank angle, about 70 % of the first order horizontal and vertical moment can be reduced by re-designing the crank angle non-uniformly.

고하중 차량의 다목적 테스트를 위한 다축 가진 테이블의 기구학 해석 (Kinematic Analysis of Multi Axis Shaking Table for Multi-Purpose Test of Heavy Transport Vehicle)

  • 진재현;나홍철;전승배
    • 제어로봇시스템학회논문지
    • /
    • 제18권9호
    • /
    • pp.823-829
    • /
    • 2012
  • An excitation table is commonly used for vibration and ride tests for parts or assemblies of automobiles, aircrafts, or other heavy systems. The authors have analyzed several kinematic properties of an excitation table that is under development for heavy transport vehicles. It consists of one table and 7 linear hydraulic actuators. The authors have performed mobility analysis, inverse kinematics, forward kinematics, and singularity analysis. Especially, we have proposed a fast forward kinematic solution considering the limited motion of the excitation table. On the assumption that the motion variables such as rotation angles and displacements are small, the forward kinematic problem is converted to the observer problem of a linear system. This provides a fast solution. Also we have verified that there are no singularity points in the working range by numerical analysis.

Parameters affecting the seismic response of buildings under bi-directional excitation

  • Fontara, Ioanna-Kleoniki M.;Kostinakis, Konstantinos G.;Manoukas, Grigorios E.;Athanatopoulou, Asimina M.
    • Structural Engineering and Mechanics
    • /
    • 제53권5호
    • /
    • pp.957-979
    • /
    • 2015
  • The present paper investigates the influence of the orientation of the ground-motion reference axes, the seismic incident angle and the seismic intensity level on the inelastic response of asymmetric reinforced concrete buildings. A single storey asymmetric building is analyzed by nonlinear dynamic analyses under twenty bi-directional ground motions. The analyses are performed for many angles of incidence and four seismic intensity levels. Moreover three different pairs of the horizontal accelerograms corresponding to the input seismic motion are considered: a) the recorded accelerograms, b) the corresponding uncorrelated accelerograms, and c) the completely correlated accelerograms. The nonlinear response is evaluated by the overall structural damage index. The results of this study demonstrate that the inelastic seismic response depends on the orientation of the ground-motion reference axes, since the three individual pairs of accelerograms corresponding to the same ground motion (recorded, uncorrelated and completely correlated) can cause different structural damage level for the same incident angle. Furthermore, the use of the recorded accelerograms as seismic input does not always lead to the critical case of study. It is also shown that there is not a particular seismic incident angle or range of angles that leads to the maximum values of damage index regardless of the seismic intensity level or the ground-motion reference axes.

Pressure distribution and aerodynamic forces on stationary box bridge sections

  • Ricciardelli, Francesco;Hangan, Horia
    • Wind and Structures
    • /
    • 제4권5호
    • /
    • pp.399-412
    • /
    • 2001
  • Simultaneous pressure and force measurements have been conducted on a stationary box deck section model for two configurations (namely without and with New Jersey traffic barriers) at various angles of incidence. The mean and fluctuating aerodynamic coefficients and pressure coefficients were derived, together with their spectra and with the coherence functions between the pressures and the total aerodynamic forces. The mean aerodynamic coefficients derived from force measurements are first compared with those derived from the integration of the pressures on the deck surface. Correlation between forces and local pressures are determined in order to gain insight on the wind excitation mechanism. The influence of the angle of incidence on the pressure distribution and on the fluctuating forces is also analysed. It is evidenced how particular deck section areas are more responsible for the aerodynamic excitation of the deck.

진자 시스템에서의 새로운 도약 현상의 실험적 관측과 이론적 해석 (Experimental Observation of New Jumping Phenomena in the Pendulum System and Its Analytical Approach)

  • 최동준;정완섭;김수현
    • 소음진동
    • /
    • 제6권4호
    • /
    • pp.439-446
    • /
    • 1996
  • This paper introduces a newly designed pendulum system that enables the more accurate boservation of dynamic behaviour arising from both horizontal and vertical(i.e. two dimension) excitation. First, experiments were carried out to examine the frequency responses of the devised pendulum system. Interestingly, experimental results for the three excitation angles of 22, 32 and 48 degree show 'new' jump phenomena. For the further understanding of these phenomena, experimental investigationhas been made to identify the equation of motion of the pendulum system from experimental data. This attempt has revealed that the viscous, coulomb and aerodynamic damping factors are involved in the equation of motion. By applying the Ritz averaging method to the equation, it becomes apparent that the jumping phenomena of the pendulum system in this work is more theoretically understood.

  • PDF

Combination resonances of imperfect SSFG cylindrical shells rested on viscoelastic foundations

  • Foroutan, Kamran;Ahmadi, Habib
    • Structural Engineering and Mechanics
    • /
    • 제75권1호
    • /
    • pp.87-100
    • /
    • 2020
  • The present paper investigates the combination resonance behavior of imperfect spiral stiffened functionally graded (SSFG) cylindrical shells with internal and external functionally graded stiffeners under two-term large amplitude excitations. The structure is embedded within a generalized nonlinear viscoelastic foundation, which is composed of a two-parameter Winkler-Pasternak foundation augmented by a Kelvin-Voigt viscoelastic model with a nonlinear cubic stiffness, to account for the vibration hardening/softening phenomena and damping considerations. With regard to classical plate theory of shells, von-Kármán equation and Hook law, the relations of stress-strain are derived for shell and stiffeners. The spiral stiffeners of the cylindrical shell are modeled according to the smeared stiffener technique. According to the Galerkin method, the discretized motion equation is obtained. The combination resonance is obtained by using the multiple scales method. Finally, the influences of the stiffeners angles, foundation type, the nonlinear elastic foundation coefficients, material distribution, and excitation amplitude on the system resonances are investigated comprehensively.