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Modeling of sound transmitted, into a cavity through a composite plate using coupled FE/BE method and control of acoustic pressure using piezoelectric actuators

Modeling of sound transmitted, into a cavity through a compo...

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smart structures and materials 1999 Conference

作者： Shi, YC Mei, C Analyt Serv & Mat Inc Hampton VA 23666 USA

ISBN: (纸本)0819431419

A coupled finite element/boundary element method is developed for the fully coupled structural/acoustic/piezoelectric system. This approach uses the dual reciprocity boundary element method to describe time dependent acoustic field and the finite element to structures and piezoelectric materials. A time-domain formulation of the coupled method is obtained. Based on the coupled time domain formulation, a linear quadratic regulator and a feedforward controller are applied to reduce the acoustic pressure transmitted into a cavity through a composite plate using embedded piezoelectric actuators. The controls of interior acoustic fields due to excitations at different frequencies are investigated, transmission losses and deflection of the plates of the controlled and uncontrolled systems are presented.

关键词： finite element method boundary element method composites structural/acoustic interaction piezoelectric material actuators feedforward linear quadratic regulator

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Approximation of distributed control laws using distributed electronic devices for vibration control

Approximation of distributed control laws using distributed ...

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smart structures and materials 1999 Conference

作者： Lenczner, M Kader, M Mrcarica, Z Univ Franche Comte Equipe Math Besancon UMR 6623 F-25030 Besancon France

ISBN: (纸本)0819431419

In this work the control of vibration in an elastic plate, by piezoelectric transducers, is considered. The model of the plate is that presented in [2]. An approximation of the optimal controller by a derivative partial operator is given. It is based on a development in series of the Riccati operator with respect to the reverse of the stiffness. Its implementation in term of distributed analog electronic circuits, is developed. Numerical simulations, obtained by the coupling of Finite Elements code and a circuit simulator, Alecsis, are presented. To improve the preceding result an iterative algorithm. of approximation of the optimal controller, being able to be: implemented by an electronic circuit, is developed. The algorithm is inspired by the approach of [4].

关键词： Sensors Electronic circuits 3D modeling Analog electronics Vibration control Actuators control systems Differential equations Electronic components Mathematical modeling

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Position control of a two-link flexible manipulator using piezoelectric actuators

Position control of a two-link flexible manipulator using pi...

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smart structures and materials 1999 Conference

作者： Choi, SB Shin, HC Kim, HK Kim, JH Inha Univ Dept Mech Engn Smart Mat & Struct Lab Inchon 402751 South Korea

ISBN: (纸本)0819431419

This paper presents a hybrid actuator scheme to actively control the end-point position of a two-link flexible manipulator. A highly nonlinear system model including inertial effects is established using Lagrange's equation associated with assumed mode method. control scheme consists of four different actuators;two servo-motors at the hubs and two piezoceramics bonded to the surfaces of the flexible links. Two sliding hyperplanes which have time varying parameters are designed for two servo-motors. The surface gradients of the hyperplanes are determined by pole assignment technique to guarantee the stability on the hyperplanes themselves. The sliding mode controllers corresponding to the hyperplanes are then synthesized on the basis of sliding mode conditions. During the motion, undesirable oscillations caused by the torques based on the rigid link dynamics an actively suppressed by applying feedback control voltages to the piezoceramic actuators. Consequently, desired rip motion is achieved. In order to demonstrate the effectiveness of the proposed methodology experiments are performed for the regulating and tracking control problem.

关键词： flexible manipulator piezoelectric actuator position control sliding mode control

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Active and passive noise control using electro-active polymer actuators (EAPA)

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Proceedings of SPIE - The International Society for Optical Engineering 1999年第I期3668卷 244-249页

作者： Ramanathan, S. Zhu, B. Chang, W. Varadan, V.V. Varadan, V.K. Pennsylvania State Univ University Park United States

Electro-active polymer actuators (EAPA) have been a topic of research interest in the recent decades due to their ability to produce large strains under the influence of relatively low electric fields as compared to commercially available actuators. This paper investigates the feasibility of Electro-Active Polymer Actuators (EAPA) for active and passive cabin noise control. The passive damping characteristics of EAPA were determined, by measuring the transmission loss of four samples of various thickness and composition in an anechoic chamber in the 200-2000 Hz frequency range. This was then compared to that of Plexiglas and silicone rubber sheets of comparable thickness. The transmission loss of EAPA and Plexiglas were observed to be the about the same. The transmission loss of EAPA was greater than that of silicone rubber, of the same thickness. The experimental and theoretical results computed using the mass law agree well. EAPA produces a strain of 0.006 for an applied field of 1 V/m. The ability of EAPA to potentially provide active as well as passive damping in the low to intermediate frequency range, along with being light-weight, pliable and transparent, makes it attractive for noise control applications as active/passive windows or wall papers.

关键词： Intelligent structures

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control system design for structural systems under statistical parametric uncertainty

Control system design for structural systems under statistic...

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smart structures and materials 1999 Conference

作者： Huerta-Ochoa, R Johnson, SH Lehigh Univ Dept Mech Engn & Mech Bethlehem PA 18015 USA

ISBN: (纸本)0819431419

This paper presents a statistical approach to the controller design process for structural systems represented by uncertain models. The plant model uncertainty is here accounted for in terms of first- and second-order statistics of uncertain parameters. The basic idea is to make the closed-loop system stability as robust as possible to statistical variations of uncertain plant model parameters. First, an approximate expression for the root variance of an uncertain polynomial is derived as a function of second-order statistics of the polynomial coefficients. The expression is specialized to the case of an SISO closed-loop system characteristic polynomial, where the uncertainty is due to statistical variability of model parameters. Uncertainty cost functions intended to represent the uncertainty of the closed-loop pole locations are then constructed. By parameterizing the set of controllers that yield a desired characteristic polynomial, the uncertainty cost function minimization is converted into a constrained optimization problem. This scheme is illustrated with an SISO seismic control system previously studied in the literature. By comparing the predicted closed-loop pole variance to numerical results obtained from Monte Carlo simulations, it is concluded that the expression developed here provides an excellent approximation, with the advantage of being an analytical expression that is suitable for use in multi-objective optimization design algorithms.

关键词： structural control uncertain polynomials smart structures control uncertain models

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Impact analysis of automotive structures with distributed smart material systems

Impact analysis of automotive structures with distributed sm...

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smart structures and materials 1999 Conference

作者： Peelamedu, SM Naganathan, NG Buckley, S Univ Toledo MIME Dept Toledo OH 43606 USA

ISBN: (纸本)0819431419

New class of automobiles has structural skins that are quite different from their current designs. Particularly, new families of composite skins are developed with new injection molding processes. These skins while support the concept of lighter vehicles of the future, are also susceptible to damage up on impact. It is important that their design should be based on a better understanding on the type of impact loads and the resulting strains and damage. It is possible that these skins can be integrally designed with active materials to counter damages. This paper presents a preliminary analysis of a new class of automotive skins, using piezoceramic as a smart material. The main objective is to consider the complex system with, the skin to be modeled as a layered plate structure involving a lightweight material with foam and active materials imbedded on them. To begin with a cantilever beam structure is subjected to a load through piezoceramic and the resulting strain at the active material site is predicted accounting for the material properties, piezoceramic thickness, adhesive thickness including the effect of adhesives. A finite element analysis is carried out to compare experimental work. Further work in this direction would provide an analytical tool that will provide the basis for algorithms to predict and counter impacts in the future class of automobiles.

关键词： piezoceramic smart material impact damage health monitoring composite cars finite element method numerical methods safety systems and automobile

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Active suppression of plate vibration with piezoceramic actuators/sensors using multiple adaptive feedfoward with feedback loop control algorithm

Active suppression of plate vibration with piezoceramic actu...

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smart structures and materials 1999 Conference

作者： Kim, YS Kim, I Lee, C Moon, CY Kumoh Natl Univ Technol Sch Mech Engn Kumi 730701 Kyungbuk South Korea

ISBN: (纸本)0819431419

This paper presents a methodology to suppress the vibration of thin rectangular plate clamped all edges. Intelligent materials such as the piezoelectric ceramic are used as actuators and sensors. The experimental modeling technique, i.e., the state-space frequency domain identification, is introduced to model the complex shaped structures bonded with noncollocated actuators/sensors. This method is much free from the Multi-Input Multi-Output (MIMO) model order problem caused at the digital implementation and also reduces distortion of the signal. In control scheme, the adaptive feedforward with feedback control algorithm is adopted since it is robust for both the transient and persistent external disturbances. The adaptive feedforward control uses the well known Multiple filtered-x LMS(least mean square) algorithm. The MIMO error path dynamics is controlled by the feedback loop which is constructed by multivariable digital LQG(Linear Quadratic Gaussian) controller composed of the regulator and Kalman filter. Experiment results demonstrate the effective reduction of the vibration label and the robustness for both the transient and persistent external disturbances.

关键词： active control piezoelectric optimal control feedforward Kalman filter

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Optimal vibration control of adaptive-aircraft wings carrying externally mounted stores and exposed to blast loading

Optimal vibration control of adaptive-aircraft wings carryin...

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smart structures and materials 1999 Conference

作者： Na, S Librescu, L Korea Polytechn Univ Dept Automat Engn Keongki Do 429450 South Korea

ISBN: (纸本)0819431419

A study of optimal vibration control of aircraft wings carrying externally mounted stores and exposed to blast loading is presented. The wing structure is modelled as a thin-walled beam of closed cross-section contour, and a number of non-classical features such as transverse shear, secondary warping, and anisotropy of the constituent materials are included. The wing structure can carry underwing and/or tip stores. The control is achieved via the use of actuating and sensing-capabilities provided by piezoelectric devices which are bonded or embedded into the host structure. The cases of piezoactuators spread over the entire span of the structure, or in the form of a patch are considered, and issues related with the influence of patch location and size upon the vibration control efficiency of wings carrying external stores are discussed. Other issues related with the minimization of the required input power and of those generated by the inclusion/discard in the quadratic performance index of time-dependent external excitations are also addressed.

关键词： optimal control dynamic response aircraft wings external stores piezopatch piezoactuators

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Stiffness of smart composites with shape memory alloy fibers in the presence of matrix cracks

Stiffness of smart composites with shape memory alloy fibers...

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smart structures and materials 1999 Conference

作者： Birman, V Univ Missouri Engn Educ Ctr St Louis MO 63121 USA

ISBN: (纸本)0819431419

The paper presents a methodology for evaluating the effective stiffness of unidirectional composite materials with shape memory alloy (SMA) fibers in the presence of matrix cracks. The solution is obtained for the case where SMA fibers in the intact composite are in the austenitic phase. However, elevated stresses in the sections of SMA fibers adjacent to the crack planes cause the martensitic transformation affecting the stiffness of the material. The solution has to account for thermal residual stresses in SMA and "ordinary" fibers and in the matrix. The order of magnitude of these stresses is calculated in the paper for two representative composite systems. As follows from the numerical examples, thermal residual stresses in the SMA fibers increase proportionally to their volume fraction but remain relatively small. However, thermal stresses in the matrix may reach rather high values reducing the strength of the matrix by a significant factor.

关键词： shape memory alloy composites matrix cracks stress-induced phase transformation residual thermal stresses

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Matrix method for analyzing structural-acoustic power efficiency

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3667卷 512-523页

作者： Cao, Renfang Leo, Donald J. Virginia Polytechnic Inst and State Univ Blacksburg United States

This paper describes a general technique to analyze the radiation impedance and actuator power efficiency of an active structure. Using a modal expansion of the structural vibration, the sound power is conveniently expressed as an integration over the surface of the planar structure. Integrating the finite element analysis into the numerical integral makes this technique applicable to any complex geometrical planar structure under arbitrary boundary conditions. As an example, this technique is applied to study of an actuator driving circular plate with an elastic support, which could be used to simulate a rigid piston. The radiation impedance and power efficiency of this active structure are studied using eigenvalue decomposition. Using general eigenvalue decomposition, the efficiency of air acoustic arrays are also analyzed. A dynamic model of the actuator is introduced to above studies by taking into account the coupling of the actuator and its host structure. Numerical results demonstrate that the radiation impedance of rigid-body motion is comparable to the analytical solution of a baffled rigid piston. Power efficiency studies demonstrate that one or two actuators will generate high efficiency when the rigid-body modes are dominant and more actuators are needed to improve the efficiency if the flexible modes are dominant. The efficiency is related to the structure impedance. A relatively soft actuator will generate a higher efficiency at low frequencies and low efficiency at higher frequencies. In contrast, a relatively stiff actuator will have a moderate efficiency at higher frequencies.

关键词： Acoustic variables control

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