We consider a model arising in structural acoustic problems which is comprised of an acoustic chamber with flexible (elastic) walls to which piezo-ceramic devices are attached. The devices play the role of actuators a...
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ISBN:
(纸本)0819424528
We consider a model arising in structural acoustic problems which is comprised of an acoustic chamber with flexible (elastic) walls to which piezo-ceramic devices are attached. The devices play the role of actuators and sensors for the model. The mathematical description of the model is governed by a coupled system of partial differential equations (PDE's) involving the wave equation coupled with a nonlinear dynamic shell equation (modeling the wall). The main aim is to reduce a pressure/noise in the cabin by the appropriate activation of piezo-ceramic devices. The assumed periodic nature of the disturbance (noise), leads naturally to the formulation of a periodic control problem. This, in turn, is strongly linked to the problem of stabilizability of the original model. Thus, the goal of this paper is to present new results on (i) uniform stabilizability of the structural acoustic model with passive damping applied to the boundary of the acoustic chamber, and (ii) an optimal control problem with ''smart'' controls activated by piezo-ceramic patches creating suitable bending moments in the structure. The control algorithm is constructed in a feedback form via a solution of a suitable Riccati type equation. One of our results shows the boundedness of the feedback gains in spite of the strong unboundedness of the control operators. This is due to the ''regularizing'' effects of shell dynamics which are partially propagated into the ''hyperbolic'' component of the structure.
smartstructures include active control elements, hence the integration of structure design with control design in inevitable. This paper provides a step in this integration in order to achieve optimal performance. Th...
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ISBN:
(纸本)0819424528
smartstructures include active control elements, hence the integration of structure design with control design in inevitable. This paper provides a step in this integration in order to achieve optimal performance. The approach presented here solves a mixed passive and active control problem with performances characterized by the so-called mixed H2/H∞ performances.
Tensegrity structures represent a special class of tendon space structures, whose members may simultaneously perform the functions of strength, sensing, actuating and feedback control. Thus, these structures ideally m...
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ISBN:
(纸本)0819424528
Tensegrity structures represent a special class of tendon space structures, whose members may simultaneously perform the functions of strength, sensing, actuating and feedback control. Thus, these structures ideally match the definition of smartstructures. This paper introduces the concept of controllable tensegrity as a new class of smartstructures capable of large displacement. The kinematics and nonlinear dynamics of one element of this class is derived and analyzed. Pre-stressability conditions are given and a particular equilibrium identified. The equations of motion are then linearized about this equilibrium and linear parametric models generated. These are next used for controller design. For control system design some of the tendons are chosen as actuators and some as sensors and a family of dynamic controllers designed such that the control energy is minimized while requiring output variance constraints to be satisfied. Another family of controllers is designed such that the output variance is minimized while requiring input variance constraints to be satisfied. The performances of these controllers are evaluated.
This paper presents an integrated finite element-control methodology for the design/analysis of smart composite structures. The method forms part of an effort to develop an integrated computational tool that includes ...
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ISBN:
(纸本)0819424528
This paper presents an integrated finite element-control methodology for the design/analysis of smart composite structures. The method forms part of an effort to develop an integrated computational tool that includes finite element modeling;control algorithms;and deterministic, fuzzy and probabilistic optimization and integrity assessment of the structures and control systems. The finite element analysis is based on a 20 node thermopiezoelectric composite element for modeling the composite structure with surface bonded piezoelectric sensors and actuators;and control is based on the linear quadratic regulator and the independent modal space control methods. The method has been implemented in a computer code called smartCOM. Several example problems have been used to verify various aspects of the formulations and the analysis results from the present study compare well against other numerical or experimental results. Being based on the finite element method, the present formation can be conveniently used for the analysis and design of smart composite structures with complex geometrical configurations and loadings.
This study demonstrates the feasibility of developing an integrated assembly of accurate and robust simulation tools for intelligent structures. Limitations of existing numerical models and cost associated with experi...
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ISBN:
(纸本)0819424528
This study demonstrates the feasibility of developing an integrated assembly of accurate and robust simulation tools for intelligent structures. Limitations of existing numerical models and cost associated with experimental models motivated this research. The emphasis is placed on the incorporation of structural analysis, plant modeling, control algorithm synthesis, optimization and performance evaluation into a single software package. The present paper includes finite element formulation of a coupled electromechanical smart structure with piezoelectric sensors and actuators, implementation of control design and evaluation of candidate control laws on the basis of finite element discretization. The discretized model predicts both mechanical and electrical responses due to the electromechanical loading and generates sensor output equations. An optimal independent modal space control is implemented and a rudimentary finite element-control package is developed to evaluate the performance of candidate control laws.
Material interfaces are commonly encountered in the fabrication of smart structural elements. Common examples are electrode-actuator-host material interfaces. Interface behavior is a very critical issue in the develop...
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ISBN:
(纸本)0819424528
Material interfaces are commonly encountered in the fabrication of smart structural elements. Common examples are electrode-actuator-host material interfaces. Interface behavior is a very critical issue in the development of a reliable smart structure technology. This study presents a set of analytical solutions that can be used in the computational fracture mechanics analysis of interface cracks in electronic materials and in smart structural elements. Exact solutions for 2D governing equations of piezoelectric and ideal elastic media are used. Shear and opening dislocations are modeled as discontinuities in the displacements at a piezoelectric-elastic interface. The interface is assumed to be electrically insulated. Closed form solutions are developed for stress and electric fields in a bi-material system. These solutions can be used in the analysis of interface fracture problems involving smart structural elements by applying the displacement discontinuity method.
We study dynamic deformations of a neo-Hookean composite plate with PZT sensors and actuators bonded to its top and bottom surfaces. The constitutive relation for the PZT is taken to be linear in the Green-Lagrange st...
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ISBN:
(纸本)0819424528
We study dynamic deformations of a neo-Hookean composite plate with PZT sensors and actuators bonded to its top and bottom surfaces. The constitutive relation for the PZT is taken to be linear in the Green-Lagrange strain tensor but quadratic in the driving voltage. It is shown that a simple feedback algorithm suffices to control the deformations of the plate.
The accuracy of stabilized, turreted gun systems like the 120mm gun on the M1A2 Abrams tank and the 30mm gun on the Apache helicopter are limited by, among other things, structural flexure of the gun barrel and suppor...
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ISBN:
(纸本)0819424528
The accuracy of stabilized, turreted gun systems like the 120mm gun on the M1A2 Abrams tank and the 30mm gun on the Apache helicopter are limited by, among other things, structural flexure of the gun barrel and support structure. An advanced actuation system based on piezoelectric translators and an optical fiber strain sensing system are described in conjunction with a rapid prototyping workstation for the design of distributed parameter control systems to actively minimize the effects of vibrations caused by traversing rough terrain or weapon firing.
control of longitudinal vibration and wave in a cantilevered beam is studied in this paper. The algorithm of the control system is based on the concept of active attenuation, the traveling wave of the structural respo...
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ISBN:
(纸本)0819424528
control of longitudinal vibration and wave in a cantilevered beam is studied in this paper. The algorithm of the control system is based on the concept of active attenuation, the traveling wave of the structural response can be annihilated by a control wave of opposite signature. Experimental tesults showed that the longitudinal vibration and wave have been substability suppressed in a beam.
We study the behavior of several organizations for a market based distributed control of unstable physical systems and show how a hierarchical organization is a reasonable compromise between rapid local responses with...
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ISBN:
(纸本)0819424528
We study the behavior of several organizations for a market based distributed control of unstable physical systems and show how a hierarchical organization is a reasonable compromise between rapid local responses with simple communication and the use of global knowledge. We also introduce a new control organization, the multihierarchy, and show that is uses less power than a hierarchy in achieving stability. The multihierarchy also has a position invariant response that can control disturbances at the appropriate scale and location.
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