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Vibration Control (vibration + control)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Modeling of Active Noise and Vibration Control with Finite Elements and Boundary Elements

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009
Stefan Ringwelski
A recently developed coupled finite element-boundary element modeling scheme for the design of active noise and vibration control of multi-coupled structural-acoustic systems is presented. The approach allows the computation of structural vibrations and resulting sound fields. By means of an example, the paper describes the theoretical background of the coupled approach. In order to show the performance of the developed approach, test simulations are carried out in the frequency domain. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Impedance Losses in Negative Capacitance Circuits for Semi-Passive Vibration Control with Piezo-Ceramics

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006
Robert Oleskiewicz
Damping or absorbing effect in vibration control applications with piezo elements may be customized by an external impedance shunt branch connected to the plates of the piezo element. The negative capacitance present in the shunt significantly improves the damping and absorbing performance of such systems. The circuit is built up of an electronic gyrator realized by the operational amplifier, which is in reality not the ideal element. Therefore the performance of the proposed systems is limited, concerning the maximum voltages and currents at which the operational amplifiers can operate. In the paper, the finite gain of the operational amplifier, together with the loss impedances and the feedback gain factor is studied. The influence of the certain imperfections in the design of the electronic gyrator is based on 1DOF mechanical oscillator, with a piezo stack. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effect of soil interaction on the performance of liquid column dampers for seismic applications

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2005
Aparna Ghosh
Abstract The effects of soil,structure interaction (SSI) while designing the liquid column damper (LCD) for seismic vibration control of structures have been presented in this study. The formulation for the input,output relation of a flexible-base structure with attached LCD has been presented. The superstructure has been modelled by a single-degree-of-freedom (SDOF) system. The non-linearity in the orifice damping of the LCD has been replaced by equivalent linear viscous damping by using equivalent linearization technique. The force,deformation relationships and damping characteristics of the foundation have been described by complex valued impedance functions. Through a numerical stochastic study in the frequency domain, the various aspects of SSI on the functioning of the LCD have been illustrated. A simpler approach for studying the LCD performance considering SSI, using an equivalent SDOF model for the soil,structure system available in literature by Wolf (Dynamic Soil,Structure Interaction. International Series in Civil Engineering and Engineering Mechanics. Prentice-Hall: Englewood Cliffs, NJ, 1985) has also been presented. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Adaptive bang,bang control for the vibration control of structures under earthquakes

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 13 2003
C. W. Lim
Abstract An adaptive method based on the modified bang,bang control algorithm is proposed for the vibration control of structures subjected to unexpected severe seismic loads greater than the design loads. A hydraulic-type active mass damper was made and experiments were carried out in the laboratory using a one-story test structure and a five-story test structure with the active mass damper. Through numerical simulations and experiments it was confirmed that the proposed method works well to suppress the vibration of structures subjected to unexpected severe seismic loads greater than the design loads without causing any unstable situations. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Optimal vibration control of continuous structures by FEM: Part I,the optimality equations

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2002
W. Szyszkowski
Abstract The governing equations of the problem of optimal vibration control of continuous linear structures are derived in the form of a set of fourth-order ordinary differential equations in the time domain. The equations decouple in the modal space and become suitable for handling by the FEM technique with the time domain subdivided into ,finite time' elements of class C1. It is demonstrated that the standard beam element with cubic Hermitian interpolation functions, routinely used in a static analysis of beams, can conveniently be substituted for the required ,finite time' element. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Optimal solid shell element for large deformable composite structures with piezoelectric layers and active vibration control

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2005
X. G. Tan
Abstract In this paper, we present an optimal low-order accurate piezoelectric solid-shell element formulation to model active composite shell structures that can undergo large deformation and large overall motion. This element has only displacement and electric degrees of freedom (dofs), with no rotational dofs, and an optimal number of enhancing assumed strain (EAS) parameters to pass the patch tests (both membrane and out-of-plane bending). The combination of the present optimal piezoelectric solid-shell element and the optimal solid-shell element previously developed allows for efficient and accurate analyses of large deformable composite multilayer shell structures with piezoelectric layers. To make the 3-D analysis of active composite shells containing discrete piezoelectric sensors and actuators even more efficient, the composite solid-shell element is further developed here. Based on the mixed Fraeijs de Veubeke,Hu,Washizu (FHW) variational principle, the in-plane and out-of-plane bending behaviours are improved via a new and efficient enhancement of the strain tensor. Shear-locking and curvature thickness locking are resolved effectively by using the assumed natural strain (ANS) method. We also present an optimal-control design for vibration suppression of a large deformable structure based on the general finite element approach. The linear-quadratic regulator control scheme with output feedback is used as a control law on the basis of the state space model of the system. Numerical examples involving static analyses and dynamic analyses of active shell structures having a large range of element aspect ratios are presented. Active vibration control of a composite multilayer shell with distributed piezoelectric sensors and actuators is performed to test the present element and the control design procedure. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Manoeuvring and vibration reduction of a flexible spacecraft integrating optimal sliding mode controller and distributed piezoelectric sensors/actuators

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2007
Qinglei Hu
Abstract This investigation is to apply optimal sliding mode (OSM) control theory and distributed piezoelectric sensor/actuator technology to vibration control of a flexible spacecraft. An approximate analytical dynamic model of a slewing flexible spacecraft with surface-bonded piezoelectric sensors/actuators is developed using Hamilton's principle with discretization by assumed model method. To satisfy pointing requirements and simultaneously suppress vibration, two separate control loops are adopted. The first uses the piezoceramics as sensors and actuators to actively suppress certain flexible modes by designing a positive position feedback (PPF) compensators that add damping to the flexible structures in certain critical modes in the inner feedback loop; then a second feedback loop is designed using OSM control to slew the spacecraft. The OSM controller minimizes the expected value of a quadratic objective function consisting of only the states with the constraints that the error states always remain on the intersection of sliding surfaces. The advantage in this method is that the vibration reduction and attitude control are achieved separately in the two separate feedback loops, allowing the pointing requirements and simultaneous vibrations suppression to be satisfied independently of one another. An additional attraction of the design method is that the selection of PPF gain is determined by introducing a cost function to be minimized by the feedback gains which are subject to the stability criterion at the same time, such that the feedback gains are selected in a more systematical way to avoid the arbitrary selecting of feedback gains. The proposed control strategy has been implemented on a flexible spacecraft, which is a hub with a cantilever flexible beam appendage and can undergo a single axis rotation. Both analytical and numerical results are presented to show the theoretical and practical merits of this approach. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Rejection of periodic disturbances of unknown and time-varying frequency

INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 2-3 2005
Marc Bodson
Abstract The paper reviews available methods for the rejection of periodic disturbances. Such disturbances are often encountered in active noise and vibration control, due to rotating machinery. The emphasis of the paper is on feedback control problems where reference sensors are not available. The case where the frequency of the disturbance is known is considered first. Two sets of algorithms are discussed: one based on the internal model principle of feedback control theory, and the second based on adaptive feedforward cancellation. An interesting observation is that algorithms originating from both approaches can be shown to be equivalent under certain conditions. When the frequency of the disturbance is unknown, an intuitive approach consists in combining a method for the rejection of disturbances of known frequency with a frequency estimator. Alternatively, one may seek to develop a stable adaptation mechanism so that the disturbance is cancelled asymptotically. While algorithms can be designed to adapt to plant and disturbance parameters, the most successful approaches use some limited plant information to adapt the magnitude, frequency, and phase parameters of the control signal. Applications are discussed throughout the paper. Copyright © 2004 John Wiley & Sons, Ltd. [source]