• 제목/요약/키워드: 2 degrees of freedom

검색결과 409건 처리시간 0.023초

3D nonlinear mixed finite-element analysis of RC beams and plates with and without FRP reinforcement

  • Hoque, M.;Rattanawangcharoen, N.;Shah, A.H.;Desai, Y.M.
    • Computers and Concrete
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    • 제4권2호
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    • pp.135-156
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    • 2007
  • Three 3D nonlinear finite-element models are developed to study the behavior of concrete beams and plates with and without external reinforcement by fibre-reinforced plastic (FRP). All three models are formulated based upon the 3D theory of elasticity. The stress model is modified from the element developed by Ramtekkar, et al. (2002) to incorporate material nonlinearity in the formulation. Both transverse stress and displacement components are used as nodal degrees-of-freedom to ensure the continuity of both stress and displacement components between the elements. The displacement model uses only displacement components as nodal degrees-of-freedom. The transition model has both stress and displacement components as nodal degrees-of-freedom on one surface, and only displacement components as nodal degrees-of-freedom on the opposite surface. The transition model serves as a connector between the stress and the displacement models. The developed models are validated by comparing the results of the analyses with an existing experimental result. Parametric studies of the effects of the externally reinforced FRP on the load capacity of reinforced concrete (RC) beams and concrete plates are performed to demonstrate the practicality and the efficiency of the proposed models.

2자유도를 갖는 3차원 운동 시뮬레이터 연구 (Implementation of 3D Motion Simulator with Two Degrees of Freedom)

  • 최명환;김영진
    • 산업기술연구
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    • 제21권A호
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    • pp.81-88
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    • 2001
  • In this work, we have developed a 2 degrees of freedom(DOF) motion simulator that can generate the sensation of motion in a 6 DOF space. The motion base has the DOF of roll and pitch, and the purpose of the motion base is to create the sensation of riding a vehicle in a 3D space by controlling the motion base. The dynamics of the mechanism was analysed and the optimal design of the motion base mechanism has been reached. The prototype motion base mechanism was developed and tested. The multi-axis motion controller(MMC) was used to control the two AC servo meters that drive the roll and pitch motion.

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정규화법에 의한 2자유도 제어계에서 제어기의 설계 (Design of controller in control system with two degrees of freedom by the normal method)

  • 하홍곤
    • 융합신호처리학회논문지
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    • 제12권1호
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    • pp.56-61
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    • 2011
  • 많은 제어기법들이 제어계의 제어성능을 개선하기 위해 제안되고 있다. 제어계에서 제어에 대한 자유도는 독립적으로 조정할 수 있는 페루프 전달함수의 수로 결정된다. 목표치 추종 및 외란억제에 2자유도 제어기법이 많이 이용되고 있다. 본 논문에서는 PID 제어기를 2자유도 제어기법을 이용하여 제어계를 설계할 수 있는 정규화법을 제안하였다. 제안한 설계법은 제어대상의 전달함수의 계수값을 이용하여 계의 전달함수를 정규화 하고, 제어기의 계수들이 결정되도록 하였다. 이 방법으로 설계된 제어계를 이용하여 2자유도 제어계를 구성하였고, 시뮬레이션 결과를 통하여 제안한 알고리즘의 유효성을 확인 하였다.

외란관측기 기반한 2 자유도 제어계의 설계 (Design of control system with two degrees of freedom based on the disturbance observer)

  • 하홍곤
    • 융합신호처리학회논문지
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    • 제11권1호
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    • pp.74-79
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    • 2010
  • 많은 제어기법들이 제어계의 제어성능을 개선하기 위해 제안되고 있다. 제어계에서 제어에 대한 자유도는 독립적으로 조정할 수 있는 폐루프 전달함수의 수로 결정된다. 목표치 추종 및 외란억제에 대해 2자유도 제어기법이 많이 이용되고 있다. 본 논문에서는 외란을 제거하기 위해 외란관측기를 갖는 제어계를 2자유도 제어계로 변환시켰으며, 기동 및 부하변동 시 과도응답의 제거를 용이하게 하였다. 그리고 외란관측기의 설계법이 주파수 영역으로 제안하였으며, 이 방법으로 설계된 외란관측기를 이용하여 2자유도 제어계를 구성하였다. 시뮬레이션 결과를 통하여 제안한 알고리즘의 유효성을 확인 하였다.

Expansion of Measured Static and Dynamic Data as Basic Information for Damage Detection

  • Eun, Hee-Chang;Lee, Min-Su;Chung, Chang-Yong;Kwak, No-Hyun
    • Architectural research
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    • 제10권2호
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    • pp.21-26
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    • 2008
  • The number of measured degrees of freedom for detecting the damage of any structures is usually less than the number of model degrees of freedom. It is necessary to expand the measured data to full set of model degrees of freedom for updating modal data. This study presents the expansion methods to estimate all static displacements and dynamic modal data of finite element model from the measured data. The static and dynamic methods are derived by minimizing the variation of the potential energy and the Gauss's function, respectively. The applications illustrate the validity of the proposed methods. It is observed that the numerical results obtained by the static approach correspond with the Guyan condensation method and the derived static and dynamic approaches provide the fundamental idea for damage detection.

Microcontroller based split mass resonant sensor for absolute and differential sensing

  • Uma, G.;Umapathy, M.;Kumar, K. Suneel;Suresh, K.;Josephine, A. Maria
    • Smart Structures and Systems
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    • 제5권3호
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    • pp.279-290
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    • 2009
  • Two degrees of freedom resonant systems are employed to improve the resonant property of resonant sensor, as compared to a single degree of freedom resonant system. This paper presents design, development and testing of two degrees of freedom resonant sensor. To measure absolute mass, cantilever shaped two different masses (smaller/absorber mass and bigger/drive mass) with identical resonant frequency are mechanically linked to form 2 - Degree-of-Freedom (DOF) resonator which exhibits higher amplitude of displacement at the smaller mass. The same concept is extended for measuring differential quantity, by having two bigger mass and one smaller mass. The main features of this work are the 3 - DOF resonator for differential detection and the microcontroller based closed loop electronics for resonant sensor with piezoelectric sensing and excitation. The advantage of using microcontroller is that the method can be easily extended for any range of measurand.

주자유도 선정 기법에 의한 동하중의 등가 정하중으로의 변환 (Transformation of Dynamic Loads into Equivalent Static Loads by the Selection Scheme of Primary Degrees of Freedom)

  • 김현기;조맹효
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1316-1321
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    • 2003
  • The systematic method to construct equivalent static load from the given dynamic load is proposed in the present study. Previously reported works to construct equivalent static load were based on ad hoc methods. They may results in unreliable structural design. The present study proposes a selection scheme of degrees of freedom(d.o.f) for imposing the equivalent static loads. The d.o.fs are selected by Two-level condensation scheme(TLCS). TLCS consists of two two-steps. The first step is the energy estimation in element-level and the second step consists of the traditional sequential elimination precudure. Through several numerical examples, the efficiency and reliability of proposed scheme is verified.

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차량동역학 해석 프로그램 AutoDyn7의 동력전달장치 모델 (Development of Powertrain Model for Vehicle Dynamic Analysis Program, AutoDyn7)

  • 손정현;유완석;김두현
    • 한국자동차공학회논문집
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    • 제9권2호
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    • pp.185-191
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    • 2001
  • In many papers, the powertrain system generally has been madeled as one-dimensional torque model. One-dimensional powertrain model may calculate the torque correctly but it does not consider the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle body frame and suspension. To consider the non-rotational degrees of freedom, the differential is modeled as a three-dimensional rigid body in this paper. A constant velocity joint is newly formulated and a relative constraint is also formulated to model the motion transfer due to gear ratio of the differential. Implementing the proposed powertrain system in the multibody model, more detail dynamic responses can be obtained. Obtained outputs such as reaction torques on the constant velocity joint and reaction forces on the rack can be useful data in the design of a powertrain.

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주자유도 선정을 위한 2단계 축소기법의 제안과 축소시스템 구성에 관한 연구 (Two-Level Scheme for Selection of Degrees of freedom by Energy Estimation Combined with Sequential Elimination)

  • 김현기;조맹효
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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    • pp.87-94
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    • 2004
  • A number of approximate techniques have been developed to calculate the eigenvalues in a reduced manner. These schemes approximate the lower eigenvalues that represent the global behavior of the structures. In general, sequential elimination has been widely used with reliability. But it takes excessively large amount of time to construct a reduced system. The present study proposes two-level condensation scheme(TLCS). In the first step, the candidate elements are selected by element-level energy estimation. In the second step, master degrees of freedom are selected by sequential elimination from the candidate degrees of freedom linked to the selected elements in the first step. Numerical examples demonstrate that the proposed method saves computational cost effectively and provides a reduced system which predicts the accurate eigenvalues of global system.

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미소 변형 및 회전 단위 벡터를 이용한 판의 대변형 해석 (Large Deflection Analysis of Plates By Using Small Local Deflections And Rotational Unit Vectors)

  • 이기수
    • 한국정밀공학회지
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    • 제17권2호
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    • pp.201-210
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    • 2000
  • The large deflection of plate is analyzed by co-rotational formulations using small local displacements and rotating unit vectors on the nodal points. The rotational degrees of the freedom are represent ed by the unit vectors1 In the nodal points, and the equilibrium equations are formulated by using small deflection theories of the plates by assuming that the directions of the unit vectors of the nodal points are known apriori. The translational degrees of freedom are independently solved from the rotational degrees of freedom in the equilibrium equations, and the correct directions of the unit vectors are computed by the iterative scheme by imposing the moment equilibrium constraint. The equilibrium equations and the associated solution procedure are explained, and the verification problems are solved.

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