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      • HARVEST
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      The finite element method simulation of active optimal vibration attenuation in structures

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      A_Sgn_Thesis_Final.pdf (1.231Mb)
      Date
      2004-04-27
      Author
      Baweja, Manish
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      The Finite Element Method (FEM) based computational mechanics is applied to simulate the optimal attenuation of vibrations in actively controlled structures. The simulation results provide the forces to be generated by actuators, as well as the structures response. Vibrations can be attenuated by applying either open loop or closed loop control strategies. In open loop control, the control forces for a given initial (or disturbed) configuration of the structure are determined in terms of time, and can be preprogrammed in advance. On the other hand, the control forces in closed loop control depend only on the current state of the system, which should be continuously monitored. Optimal attenuation is obtained by solving the optimality equations for the problem derived from the Pontryagin’s principle. These equations together with the initial and final boundary conditions constitute the two-point-boundary-value (TPBV) problem. Here the optimal solutions are obtained by applying an analogy (referred to as the beam analogy) between the optimality equation and the equation for a certain problem of static beams in bending. The problem of analogous beams is solved by the standard FEM in the spatial domain, and then the results are converted into the solution of the optimal vibration control problem in the time domain. The concept of the independent-modal-space-control (IMSC) is adopted, in which the number of independent actuators control the same number of vibrations modes. The steps of the analogy are programmed into an algorithm referred to as the Beam Analogy Algorithm (BAA). As an illustration of the approach, the BAA is used to simulate the open loop vibration control of a structure with several sets of actuators. Some details, such as an efficient meshing of the analogous beams and effective solving of the target condition are discussed. Next, the BAA is modified to handle closed loop vibration control problems. The algorithm determines the optimal feedback gain matrix, which is then used to calculate the actuator forces required at any current state of the system. The method’s accuracy is also analyzed.
      Degree
      Master of Science (M.Sc.)
      Department
      Mechanical Engineering
      Program
      Mechanical Engineering
      Supervisor
      Szyszkowski, Walerian
      Committee
      Watson, L. Glen; Oguocha, Ikechukwuka N.; Burton, Richard T.; Boulfiza, Mohamed
      Copyright Date
      April 2004
      URI
      http://hdl.handle.net/10388/etd-04302004-080403
      Subject
      feedback gain
      Optimal gains
      Modal space
      Open loop control
      Finite Elements
      Actuators
      Optimal vibration control
      Computational mechanics
      Simulation
      Beam Analogy
      observability
      Sensors
      Controllability
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      • Graduate Theses and Dissertations
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