• Title/Summary/Keyword: Modal Characteristic

Search Result 231, Processing Time 0.026 seconds

Vibration Analysis of a Cracked Beam with a Concentrated Mass Undergoing Rotational Motion (크랙과 집중질량을 갖는 회전 외팔보의 진동 해석)

  • Kim, Min-Kwon;Yoo, Hong-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2008.11a
    • /
    • pp.354-359
    • /
    • 2008
  • Modal characteristics of a cracked beam with a concentrated mass undergoing rotational motion are investigated in this paper. Hybrid deformation variables are employed to derive the equations of motion of a rotating cantilever beam. The flexibility due to crack, which is assumed to be open during the vibration, is calculated basing on a fracture mechanics theory. To obtain more general information, the equations of motion are transformed into a dimensionless form in which dimensionless parameters are identified. The effects of the dimensionless parameters related to the angular speed, the depth and location of a crack and the size and location of a concentrated mass on the modal characteristics of the beam are investigated numerically.

  • PDF

Response Characteristics Of Steel Frame Structuresw With Added Elastic Dampers (탄성 댐퍼가 추가된 대형철골 구조물의 응답특성)

  • Bae, Chun-Hee;Cho, Cheul-Whan;Yang, Kyeong-Hyeon;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2002.11b
    • /
    • pp.593-598
    • /
    • 2002
  • Coupling adjacent steel frame using elastic dampers for control of response to low and moderate dynamic event is investigated in this paper. The complex modal superposition method is first used to determine dynamic characteristic, mainly modal damping ratio and modal frequency, of damper linked linear adjacent steel frame for fractical use. Dynamic response of steel frame linked by hydraulic-excitation method. This combined method can efectively and accurately determine dynamic response of non-clasically damped systems in the frequency domain. Parametric studties are finally performed to identify optimal parameters of elastic dampers for achieving the maximum modal damping ratio or the maximum response reduction of steel frame. It is demonstrated that using discrete elasatic dampers of proper parameters to link steel frame can reduce dynamic response significantly.

  • PDF

Modal Analysis of Coaxial Shells with Fluid-Filled Annulus

  • Jhung, Myung-Jo;Kim, Yong-Beum;Jeong, Kyeong-Hoon;Park, Suhn
    • Nuclear Engineering and Technology
    • /
    • v.32 no.4
    • /
    • pp.328-341
    • /
    • 2000
  • Investigated in this study are the modal characteristics of the coaxial cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier series expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of the fluid-filled annulus and the boundary conditions on the modal characteristics of the coaxial shells is investigated using a finite element modeling.

  • PDF

Vibration Analysis of a Cracked Beam with a Concentrated Mass Undergoing Rotational Motion (크랙과 집중질량을 갖는 회전 외팔보의 진동 해석)

  • Kim, Min-Kwon;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.19 no.1
    • /
    • pp.10-16
    • /
    • 2009
  • Modal characteristics of a cracked beam with a concentrated mass undergoing rotational motion are investigated in this paper. Hybrid deformation variables are employed to derive the equations of motion of a rotating cantilever beam. The flexibility due to crack, which is assumed to be open during the vibration, is calculated basing on a fracture mechanics theory. To obtain more general information, the equations of motion are transformed into a dimensionless form in which dimensionless parameters are identified. The effects of the dimensionless parameters related to the angular speed, the depth and location of a crack and the size and location of a concentrated mass on the modal characteristics of the beam are investigated numerically.

MODAL CHARACTERISTIC ANALYSIS OF THE APR1400 NUCLEAR REACTOR INTERNALS FOR SEISMIC ANALYSIS

  • Park, Jong-Beom;Choi, Youngin;Lee, Sang-Jeong;Park, No-Cheol;Park, Kyoung-Su;Park, Young-Pil;Park, Chan-Il
    • Nuclear Engineering and Technology
    • /
    • v.46 no.5
    • /
    • pp.689-698
    • /
    • 2014
  • Reactor internals are sensitive to dynamic loads such as earthquakes and flow induced vibration. Thus, it is essential to identify the dynamic characteristics to evaluate the seismic integrity of the structures. However, a full-sized system is too large to perform modal experiments, making it difficult to extract data on its modal characteristics. In this research, we constructed a finite element model of the APR1400 reactor internals to identify their modal characteristics. The commercial reactor was selected to reflect the actual boundary conditions. Our FE model was constructed based on scale-similarity analysis and fluid-structure interaction investigations using a fabricated scaled-down model.

Natural vibration analysis of coaxial shells coupled with fluid

  • Jhung, Myung Jo;Choi, Young Hwan;Jeong, Kyeong Hoon
    • Structural Engineering and Mechanics
    • /
    • v.16 no.6
    • /
    • pp.655-674
    • /
    • 2003
  • Investigated in this study are the natural vibration characteristics of the coaxial cylindrical shells coupled with a fluid. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier series expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of the fluid-filled annulus and the boundary conditions on the modal characteristics of the coaxial shells is investigated using a finite element modeling.

Modal Analysis of Curved Beam. (곡선보의 모우드 해석)

  • 김영문;유기표
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2000.10a
    • /
    • pp.349-354
    • /
    • 2000
  • The modal analysis based on deformations is the method to drived dynamic responsed from superposition of natural frequency and mode shape. In order to free vibration analysis of the structures, Aluminum-made model is used in experiment. The dynamic characteristic of the structures are determined from acceleration measurements using impulse hammer. Experimenrt input and output signal are derive from impact hammer and the one accerometer. This paper present three methods for calculating the natural frequencies and mode shapes of the structure with theory value and finite element analysis, experiment. The results were good approximated about natural frequency and mode shape.

  • PDF

Frequency Window Method for the Vibration of Primary-Secondary Structural Systems (Frequency Window Method에 의한 1차-2차 구조시스템의 진동특성)

  • 민경원
    • Journal of KSNVE
    • /
    • v.1 no.1
    • /
    • pp.45-52
    • /
    • 1991
  • The dynamic properties of primary-secondary structural systems are examined using analytical expressions for the modal properties. The analysis begins with a Lagrange multiplier formulation to develop a characteristic equation in terms of primary system mobilities and secondary system impedances. The complexity of the characteristic equation by developing new method, frequency window method. It is shown that the reduction of complexity can only be obtained by a reduction of accuracy, but by retaining the dominant effects of the dynamics problem, the loss of accuracy is not excessive. The reduced problem is examined further to develop simple expressions for the modal properties which provide insight into the resonance characteristics of the primary-secondary system problem. The results are useful as a complement to existing computational techniques for understanding and interpreting dynamic analysis results.

  • PDF

Analytical Method to Analyze the Effect of Tolerance on the Modal Characteristic of Multi-body Systems in Dynamic Equilibrium (동적 평형위치에 있는 다물체계의 모드특성에 미치는 공차의 영향 분석을 위한 해석적 방법)

  • Kim, Bum-Suk;Yoo, Hong-Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.17 no.7 s.124
    • /
    • pp.579-586
    • /
    • 2007
  • Analytical method to analyze the effect of tolerance on the modal characteristic of multi-body systems in dynamic equilibrium position is suggested in this paper. Monte-Carlo method is conventionally employed to perform the tolerance analysis. However, Monte-Carlo method spends too much time for analysis and has a greater or less accuracy depending on sample condition. To resolve these problems, an analytical method is suggested in this paper. Sensitivity equations for damped natural frequencies and the transfer function are derived at the dynamic equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivities of damped natural frequencies and the transfer function can be calculated.