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Search Results: 1 - 10 of 3025 matches for " smart structures "
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Active Vibration Control of Satellite Flexible Structures during Attitude Maneuvers
Saeed Hemmati,Morteza Shahravi,Keramat Malekzadeh
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: The purpose of this study is controlling active vibration of satellite flexible structures during attitude maneuvers. A smart structure is a structure which is able to sense and control active reaction to any external factors and stimulation. As it comes from the definition of smart structures, development of this knowledge depends on the materials science development, theories and strategies for control. In materials science, smart materials are developed in such a way that they are able to sense and react in a controllable mode effectively. The smart materials are combined with conventional structures and they are used as sensors and actuators. Furthermore, smart structures subject include design, implementation methods and control systems over structures so that the control system receives signals from sensors after processing. Then, it sends signals to the actuator in order to achieve a desirable response to incoming stimuli. An issue taken into account in this monograph is active vibration control of satellite flexible structures in attitude maneuvers, which was done by the use of smart materials in satellite structure. For this purpose, a mathematical model of a satellite flexible panel was derived first. Then, a computer code was generated. Finally, by comparing the results of non-smart control and smart control, we came to this conclusion that the use of smart materials led to a decrease in the amplitude of the vibration and the reduction of the time required for damping vibrations.
Active control of smart structures - an overall approach
Nestorovi? Tamara,Trajkov Miroslav
Facta Universitatis Series : Architecture and Civil Engineering , 2010, DOI: 10.2298/fuace1001035n
Abstract: The paper presents active control of smart structures within a focused frame of piezoelectric applications in active vibration and noise attenuation with potentials for the use in mechanical and civil engineering. An overall approach to active control of piezoelectric structures involves subsequent steps of modeling, control, simulation, experimental verification and implementation. Each of these steps is regarded in details. Different application examples showing the feasibility of the active structural control will be presented.
Simulation and Modelling of Smart Beams with Robust Control Subjected to Wind Induced Vibration  [PDF]
A. Moutsopoulou, G. Stavroulakis, T. Pouliezos
Open Journal of Civil Engineering (OJCE) , 2012, DOI: 10.4236/ojce.2012.23016
Abstract: This paper presents some recent developments in modelling and numerical analysis of piezoelectric systems and controlled smart structures based on a ?nite element formulation with embedded control. The control aims at vibration suppression of the structure subjected to external disturbances, like wind and noise, under the presence of model inaccuracies, using the available measurements and controls. A smart structure under dynamic loads is analysed and comparison between results for beam with and without control is made. The numerical results show that the control strategy is very effective and suppresses the vibrations of the structure.
STUDIES ON ELECTROMECHANICAL BEHAVIOR OF SMART STRUCTURES BY EXPERIMENT AND FEM
DR. CHANDRASHEKHAR BENDIGERI,,RITU TOMAR
International Journal of Engineering Science and Technology , 2011,
Abstract: The formulation of the finite element for static analysis has been presented based on isoparametric formulation. The element considered in the present study is eight noded hexahedral elements. A computercode based on the above formulation has been developed using MATLAB software to solve the three dimensional structures integrated with piezoelements. The experiments have been conducted on the piezoelectric smart structures consisting aluminum beam with iezoelectric materials for deformation due to applied voltage, steel beam with piezoelectric materials for deformation due to applied voltage and finally natural frequency for aluminum beam with piezoelectric materials natural frequency is estimated by application of electromechanical behavior of piezomaterial. The results obtained were used for validating the present finite element code developed and found to have good agreement
Nonlinear dynamics of a SMA large-scale space structure
Paula, Aline S. de;Savi, Marcelo A.;Lagoudas, Dimitris C.;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000500009
Abstract: large-scale structures are of special interest of aerospace applications, especially the ones involving smart materials. this paper deals with an archetypal system with two degrees of freedom that resembles the use of sma elements as vibration isolation systems on a sparse aperture satellite array. the system has sma elements in two perpendicular directions connected to a mass. each sma element is connected to a base structure. imperfections are represented by establishing a comparison between two different systems: ideal and perturbed configuration system. the perturbed configuration is characterized by a situation where all sma elements are in a stress-free state. the thermomechanical behavior of sma elements is described by a constitutive model with internal constrains. numerical tests of this system are of concern showing its general dynamical behavior. periodic and chaotic motions are investigated showing the complex behaviors of this kind of system. the effect of imperfection in system dynamics is also discussed.
Vibration energy harvesting using piezoelectric transducer and non-controlled rectifiers circuits
Motter, Daniel;Lavarda, Jairo Vinícius;Dias, Felipe Aguiar;Silva, Samuel da;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000500006
Abstract: vibration energy harvesting with piezoelectric materials is of practical interest because of the demand for wireless sensing devices and low-power portable electronics without external power supply. for practical use of vibration energy harvester with piezoelectric materials, it is necessary to process the alternating current (ac) by using different rectifiers' circuits in order to charge batteries with direct current (dc) or to feed electronic devices. unfortunately, most of the models used focused on simplifying the energy harvesting circuit into a simple resistive load. in the real-world applications, the energy harvesting external circuit is more complex than a simple load resistance. in this sense, the goal of the present paper is to describe a comprehensive strategy for power harvesting device to estimate the output power provided by a cantilever beam with the electrodes of the piezoceramic layers connected to a standard rectifier circuit. the true electrical components were considered in the full-wave rectifier circuit with four diodes in bridge. a very simple and comprehensive description for choosing the capacitance and resistance loads is provided. in order to illustrate the results, numerical simulations and experimental verifications are also performed to ensure the accuracy. all tests and results are described and detailed using matlab, the simpowersystem toolbox of the simulink and an experimental setup.
Dynamic Responses of Magneto-Thermo-Electro-Elastic Shell Structures with Closed-Circuit Surface Condition
Thar M. Badri,Hussain H. Al-Kayiem
Journal of Applied Sciences , 2012,
Abstract: An analytical solution for piezolaminated shell structure and embedded smart materials is presented in this study. In this study, the fundamental theory was derived based on the generic first-order transversely shearable deformation theory involving Codazzi-Gauss geometrical discretion. The fundamental equation and its boundary conditions was strenuously derived using Hamilton’s principle with cooperating of Gibbs free energy function. The theory was casted in version of shell of revolution, in order to be simplified to account for commonly occurring sensors and actuator geometries and intended for wide range of common smart materials. Then the developed theory was solved by the generic forced-solution procedure. The responses and their frequency parameters were evaluated in the simply supported boundary condition. The results have shown a close agreement with those reported in literature. The developed theory and the presented solution procedure may serve as a reference in developing the magneto-thermo-electro-elastic shell theories and to improve the benchmark solutions for judging the existence of imprecise theories and other numerical approaches.
The use of smart structures in the realization of effective semi-active Control systems for vibration reduction
Nitzsche, Fred;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000500005
Abstract: the realization of semi-active actuators by smart structures is discussed. semi-active actuators have the advantage of consuming much less power than direct-active actuators and are appropriate for the utilization in vibration problems encountered in aeronautical applications, where the loads are in general too high for direct-active actuators to perform. the development of a compact actuator device of this class, from the design phase to the validation tests, is presented.
System identification and active vibration control of a flexible structure
Abreu, Gustavo Luiz C. M. de;Concei??o, Sanderson M. da;Lopes Jr., Vicente;Brennan, Michael John;Alves, Marco Túlio Santana;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000500007
Abstract: the aim of this paper is to illustrate the active control of vibration of a flexible structure using a model-based digital controller. the state-space model of the system is derived using a system identification technique known as the observer/kalman filter identification (okid) method together with eigensystem realization algorithm (era). based on the measured response of the structure to a random input, an explicit state-space model of the equivalent linear system is determined. the model is used in a linear quadratic regulator (lqr) to control the first two modes of vibration of a cantilever beam using a piezoelectric actuator/sensor pair. experimental results demonstrate the efficacy of the proposed approach.
A bending element for isotropic, multilayered and piezoelectric plates
Rezaiee-Pajand, M.;Sadeghi, Y.;
Latin American Journal of Solids and Structures , 2013, DOI: 10.1590/S1679-78252013000200006
Abstract: in this paper, a new 12-node triangular element is developed for the analysis of composite plates. moreover, the stress-strain relations of laminated bending plates, along with the characteristics of composite and piezoelectric materials have also been investigated. following this, a finite element formulation for smart composite bending plates is proposed. the capability of the suggested element in analyzing both composite plates and smart ones is studied via numerical examples. these analyses demonstrate that the proposed element is capable of yielding accurate results for the given problems. in addition, it is also concluded that in comparison to the elements developed by other researchers, this new formulation leads to more precise outcomes.
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