• Title/Summary/Keyword: 2 degrees of freedom

Search Result 409, Processing Time 0.022 seconds

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
    • /
    • v.4 no.2
    • /
    • pp.135-156
    • /
    • 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.

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

  • Choi, Myoung-Hwan;Kim, Young-Jin
    • Journal of Industrial Technology
    • /
    • v.21 no.A
    • /
    • pp.81-88
    • /
    • 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.

  • PDF

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

  • Ha, Hong-Gon
    • Journal of the Institute of Convergence Signal Processing
    • /
    • v.12 no.1
    • /
    • pp.56-61
    • /
    • 2011
  • Many control techniques have been proposed in order to improve the control performance of the control system. The degree of freedom on control in the control system is decided by the number of the closed-loop transfer function which can adjust independently. The controller design scheme with two degrees of freedom(TDOF) is extensively used for securing the good control performance to trace a desired value and reject disturbance. In this paper, PID controller is used by controller with TDOF and the design method for control system with TDOF is proposed by the normal method. Using the coefficients of the transfer function of the plant, the transfer function of the control system is normalized by the proposed design method and the parameters of the controller are determined. The control system with the TDOF is constructed by using this method. Through the simulation results, the usefulness of the proposed algorithm is proved.

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

  • Ha, Hong-Gon
    • Journal of the Institute of Convergence Signal Processing
    • /
    • v.11 no.1
    • /
    • pp.74-79
    • /
    • 2010
  • Many control techniques have been purposed in order to improve the control performances of the control system. The freedom on control in the control system is decided by the number of the closed-loop transfer function which can adjust independently. The design method of the controller with two degrees of freedom(TDOF) is used extensively for following the desired value and rejecting the disturbance. In this paper, the control system with the disturbance observer(DOB) for rejecting the disturbance is transformed by the control system with TDOF and the rejection of a transient response is easy at the starting time and load variation. The design method of the DOB is proposed in the frequency-domain and the control system with TDOF is constructed by using the DOB which is designed with this method. Through the simulation results, the usefulness of the proposed algorithm is proved.

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
    • /
    • v.10 no.2
    • /
    • pp.21-26
    • /
    • 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
    • /
    • v.5 no.3
    • /
    • pp.279-290
    • /
    • 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.

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

  • Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Proceedings of the KSME Conference
    • /
    • 2003.11a
    • /
    • pp.1316-1321
    • /
    • 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.

  • PDF

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

  • 손정현;유완석;김두현
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.9 no.2
    • /
    • pp.185-191
    • /
    • 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.

  • PDF

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

  • 김현기;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2004.04a
    • /
    • pp.87-94
    • /
    • 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.

  • PDF

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

  • 이기수
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.17 no.2
    • /
    • pp.201-210
    • /
    • 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.

  • PDF