• Title/Summary/Keyword: Euler-Bernoulli 보 이론

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Vibration Analysis of Rotating Inward Cantilever Beams With a Tip-Mass (집중질량을 갖는 회전중심방향 자유단 외팔보의 진동해석)

  • Lee, Gun Ho;Yoo, Hong Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.389-391
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    • 2014
  • The Vibration Analysis of Rotating Inward Beams Considering The Tip-Mass is presented based on Euler-Bernoulli beam theory. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of angular speed, and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

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Buckling oad and Post-buckling Behavior of Tapered Column with Constant Volume and Both Clamped Ends (일정체적 양단고정 변단면 기둥의 좌굴하중 및 후좌굴 거동)

  • 이병구
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.41 no.5
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    • pp.112-122
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    • 1999
  • 이 논문은 일정체적을 갖는 양단고정 변단면 기둥의 좌굴하중 및 후좌굴 거동에 관한 연구이다. 기둥의 변단면으로는 직선형, 포물선형, 정현의 선형을 갖는세 가지 변단면을 채택하였다. Bernoulli-Euler 보 이론을 이용하여 압축하중이 작용하여 좌굴된 기둥이 정확탄성곡선을 지배하는 미분방정식을 유도하였다. 유도된 미분방정식을 Runge-Kutta 법과 REgula-Falsi법을 이용하여 수치해석하였다. 수치해석의 결과로 좌굴하중, 좌굴기둥의 평형경로 및 정확탄성곡선을 산출하였다. 또한 좌굴하중-단면비 곡선으로부터 최강기둥의 좌굴하중과 단면비를 산출하였다.

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A Performance Evaluation of Beam Finite Elements with Higher-order Derivatives' Continuity (고차미분 연속성을 가지는 유한요소 보 모델들에 대한 성능평가)

  • Lee, Gijun;Kim, Jun-Sik
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.4
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    • pp.335-341
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    • 2017
  • In this paper, beam finite elements with higher-order derivatives' continuity are formulated and evaluated for various boundary conditions. All the beam elements are based on Euler-Bernoulli beam theory. These higher-order beam elements are often required to analyze structures by using newly developed higher-order beam theories and/or non-classical beam theories based on nonlocal elasticity. It is however rare to assess the performance of such elements in terms of boundary and loading conditions. To this end, two higher-order beam elements are formulated, in which $C^2$ and $C^3$ continuities of the deflection are enforced, respectively. Three different boundary conditions are then applied to solve beam structures, such as cantilever, simply-support and clamped-hinge conditions. In addition to conventional Euler-Bernoulli beam boundary conditions, the effect of higher-order boundary conditions is investigated. Depending on the boundary conditions, the oscillatory behavior of deflections is observed. Especially the geometric boundary conditions are problematic, which trigger unstable solutions when higher-order deflections are prescribed. It is expected that the results obtained herein serve as a guideline for higher-order derivatives' continuous finite elements.

The Control of Flexible Robot Arm using Adaptive Control Theory (적응제어 이론을 이용한 유연한 로봇팔의 제어)

  • Han, Jong-Kil
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.5
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    • pp.1139-1144
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    • 2012
  • The ration of payload to weight of industrial robot amounts form 1:10 to 1:30. Compared with man who have a ration of 3:1, it is very low. One of the goals for the next generation of robots will be a ration. This might be possible only by developing lightweight robots. When two-link flexible arm is rotated about an joint axis, transverse vibration may occur. In this paper, vibration dynamics of flexible arm is modeled by using Bernoulli-Euler beam theory and Lagrange equation. Using the fact that matrix $\dot{D}-2C$ is skew symmetric, new controllers which have a simplified structure with less computational burden is proposed by using Lyapunov stability theory. We propose deterministic and adaptive control laws for two link flexible arm, and the validity of the proposed control scheme is shown in computer simulation for two-link flexible arm.

A Novel Methodology of Improving Stress Prediction via Saint-Venant's Principle (생브낭의 원리를 이용한 응력해석 개선)

  • Kim, Jun-Sik;Cho, Maeng-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.2
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    • pp.149-156
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    • 2011
  • In this paper, a methodology is proposed to improve the stress prediction of plates via Saint Venant's principle. According to Saint Venant's principle, the stress resultants can be used to describe linear elastic problems. Many engineering problems have been analyzed by Euler-Bernoulli beam(E-B) and/or Kirchhoff-Love(K-L) plate models. These models are asymptotically correct, and therefore, their accuracy is mathematically guaranteed for thin plates or slender beams. By post-processing their solutions, one can improve the stresses and displacements via Saint Venant's principle. The improved in-plane and out-of-plane displacements are obtained by adding the perturbed deflection and integrating the transverse shear strains. The perturbed deflection is calculated by applying the equivalence of stress resultants before and after post-processing(or Saint Venant's principle). Accuracy and efficiency of the proposed methodology is verified by comparing the solutions obtained with the elasticity solutions for orthotropic beams.

Influence of Serial Moving Masses on Dynamic Behavior of Simply Supported Beam with Crack (크랙을 가진 단순지지 보의 동특성에 미치는 이동질량의 영향)

  • 윤한익;김영수;손인수
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.7
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    • pp.555-561
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    • 2003
  • An iterative modal analysis approach is developed to determine the effect of transverse open cracks on the dynamic behavior of simply supported Euler-Bernoulli beams with the moving masses. The influences of the velocities of moving masses, the distance between the moving masses and a crack have been studied on the dynamic behavior of a simply supported beam system by numerical method. The Presence of crack results In large deflection of beam. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. Totally, as the velocity of the moving masses and the distance between the moving masses are increased, the mid-span deflection of simply supported beam with the crack is decreased.

Moving Support Elements for Dynamic Finite Element Analysis of Statically Determinate Beams Subjected to Support Motions (지점운동을 받는 정정보의 동해석을 위한 동지점 유한요소 개발)

  • Kim, Yong-Woo;Jhung, Myung Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.4
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    • pp.555-567
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    • 2013
  • A finite element formulation for a Rayleigh-damped Bernoulli-Euler beam subjected to support motions, which accompanies quasi-static rigid-body motion, is presented by using the quasi-static decomposition method. Moving support beam elements, one of whose nodes is coincident with the moving support, are developed to represent the effect of a moving support. Statically determinate beams subjected to support motions can be modeled successfully by using moving support elements. Examples of cantilever and simply-supported beams subjected to support motions are illustrated, and the numerical results are compared with the analytical solutions. The comparison shows good agreement.

Critical Loads of Tapered Cantilever Columns with a Tip Mass (자유단 집중질량을 갖는 변단면 캔틸레버 기둥의 임계하중)

  • Jeong, Jin Seob;Lee, Byoung Koo;Kim, Gwon Sik;Kim, Jong Ung
    • Journal of Korean Society of Steel Construction
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    • v.17 no.6 s.79
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    • pp.699-705
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    • 2005
  • This paper investigates critical loads of tapered cantilever columns with a tip mass, subjected to a follower force. The linearly tapered solid rectangular cross-sections are adopted as the column taper. The differential equation governing free vibrations of such columns, also called Beck's columns, is derived using the Bernoulli-Euler beam theory. Both divergence and flutter critical loads are calculated from the load-frequency curves that are obtained by solving the differential equation. The critical loads are presented as functions of various non-dimensional system parameters, namely, the taper type, the subtangential parameter, and the mass ratio.

Spectral Element Formulation for Analysis of Lamb Wave Propagation on a Plate Induced by Surface Bonded PZT Transducers (표면 부착형 PZT소자에 의해 유발된 판 구조물의 램파 전달 해석을 위한 스펙트럼 요소 정식화)

  • Lim, Ki-Lyong;Kim, Eun-Jin;Kang, Joo-Sung;Park, Hyun-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.11
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    • pp.1157-1169
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    • 2008
  • This paper presents spectral element formulation which approximates Lamb wave propagation by PZT transducers bonded on a thin plate. A two layer beam model under 2-D plane strain condition is introduced to simulate high-frequency dynamic responses induced by a piezoelectric (PZT) layer rigidly bonded on a base plate. Mindlin-Herrmann and Timoshenko beam theories are employed to represent the first symmetric and anti-symmetric Lamb wave modes on a base plate, respectively. The Euler-Bernoulli beam theory and 1-D linear piezoelectricity are used to model the electro-mechanical behavior of a PZT layer. The equations of motions of a two layer beam model are derived through Hamilton's principle. The necessary boundary conditions associated with the electro-mechanical properties of a PZT layer are formulated in the context of dual functions of a PZT layer as an actuator and a sensor. General spectral shape functions of response field and the associated boundary conditions are obtained through equations of motions converted into frequency domain. Detailed spectrum element formulation for composing the dynamic stiffness matrix of a two layer beam model is presented as well. The validity of the proposed spectral element is demonstrated through numerical examples.

Analysis of Lamb wave propagation on a plate using the spectral element method (스펙트럼 요소법을 이용한 판 구조물의 램파 전달 해석)

  • Lim, Ki-Lyong;Kim, Eun-Jin;Choi, Kwang-Kyu;Park, Hyun-Woo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.11a
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    • pp.71-81
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    • 2008
  • This paper proposes a spectral element which can represent dynamic responses in high frequency domain such as Lamb waves on a thin plate. A two layer beam model under 2-D plane strain condition is introduced to simulate high-frequency dynamic responses induced by piezoelectric layer (PZT layer) bonded on a base plate. In the two layer beam model, a PZT layer is assumed to be rigidly bonded on a base beam. Mindlin-Herrmann and Timoshenko beam theories are employed to represent the first symmetric and anti-symmetric Lamb wave modes on a base plate, respectively. The Bernoulli beam theory and 1-D linear piezoelectricity are used to model the electro-mechanical behavior of a PZT layer. The equations of motions of a two layer beam model are derived through Hamilton's principle. The necessary boundary conditions associated with electro mechanical properties of a PZT layer are formulated in the context of dual functions of a PZT layer as an actuator and a sensor. General spectral shape functions of response field and the associated boundary conditions are formulated through equations of motions converted into frequency domain. A detailed spectrum element formulation for composing the dynamic stiffness matrix of a two layer beam model is presented as well. The validity of the proposed spectral element is demonstrated through comparison results with the conventional 2-D FEM and the previously developed spectral elements.

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