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smart structures and materials 2000 - mathematics and control in smart structures

作者： Balachandran, B. Zhao, M.X. Univ of Maryland College Park MD United States

The influence of piezoceramic actuator nonlinearities on the response of a panel-enclosure system is examined. As an extension of our earlier work, hysteresis effect is also included in the nonlinear relationship between the free strain experienced by a piezoceramic patch and the applied electric field. The responses of the system with the hysteretic effect are discussed and compared with experimental results.

关键词： Actuators

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Acoustic signature reduction using feedback of piezoelectric layers

Acoustic signature reduction using feedback of piezoelectric...

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Hamberg, Johan Malmgren, Anders Swedish Defense Research Establishment Stockholm Sweden

The possibilities of using dynamic feedback of piezoelectric layers for controlling the acoustic properties of a surface were studied. Extensive use of the Redheffer star-product for systematic modeling, analysis and synthesis of the system and the regulator was made. Results show that in principle, it is possible to achieve desired properties using a single piezo-electric layer.

关键词： Acoustic variables control

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Development of electric environment to control mollusk-shaped gel robots made of electro-active polymer PAMPS gel

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3987卷 321-330页

作者： Otake, Mihoko Inaba, Masayuki Inoue, Hirochika Univ of Tokyo Tokyo Japan

This paper describes the design and implementation of electric fields to actuate mollusk-shaped robots made entirely of PAMP gel, which is a kind of electro-active polymer (EAP). The purpose of this study is to develop a system to control the shape of both simulated and real gel robots using electric fields. We present a modeling framework and experimental results using a prototype mollusk-shaped EAP robot that locomotes by changing the shape of its whole body.

关键词： Conductive plastics

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Air flow control systems for miniature fuel cells

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Proceedings of SPIE - The International Society for Optical Engineering 2000年 3985卷 705-716页

作者： Leo, Donald J. Nasser, Khalil Virginia Tech Blacksburg United States

The feasibility of utilizing piezoelectric actuators for air flow control of low-power fuel cells is assessed using an electromechanical model of the actuator and a steady-state model for compressible flow. Expressions for electromechanical efficiency are derived using one-dimensional transducer equations of a piezoelectric actuator coupled to the pressure-volume relationships for an ideal gas. The derivation demonstrates that the mechanical power output and electrical power requirements of the system are a function of the input-output force ratio, the input force normalized to the blocked force of the actuator, and the piezoelectric coupling coefficient. The mechanical efficiency of the closed cycle is constant at 28.6% and the electrical efficiency varies from less than 1% for a coupling coefficient of 0.1 to approximately 8% for a coupling coefficient of 0.5. Expressions for the force, displacement, and work performed during each process of the four-stroke cycle are derived. A numerical example of a 50 Watt fuel cell demonstrates that only 219 mW of real mechanical power is required to deliver the necessary air flow to the fuel cell. Operating frequencies are approximately 600 Hz for actuators with 1 mm free displacement. Dissipation in the power electronics is between 6 and 19 Watts for linear amplifiers but can be reduced to less than 2 Watts for more efficient switching-type power conditioners. This example demonstrates that piezoelectric actuators are a viable technology for fuel cell air flow control when they are used in conjunction with efficient power electronics.

关键词： Fuel cells

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High bandwidth tunability in a smart vibration absorber

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JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND structures 2000年第12期11卷 923-929页

作者： Flatau, AB Dapino, MJ Calkins, FT Iowa State Univ Ames IA 50011 USA Boeing Phantom Works Seattle WA 98124 USA

An electrically tunable vibration absorber based on the strong DeltaE effect of Terfenol-D has been developed. A general description of tuned vibration absorbers is presented along with a description of the magnetostrictive effects that make an electrically tunable Terfenol-D vibration aborber function. It is emphasized that the large modulus changes achievable with the proposed magnetostrictive vibration absorber arise as a consequence of the stiffening of the crystal lattice as the magnetic field is increased from the demagnetized state to magnetic saturation. This is in contrast to the small modulus changes often reported in the literature which are achieved by operating smart materials between their open- and short-circuit states. Experimental results are presented that show agreement with prior art and demonstrate control of a magnetostrictive actuator resonant frequency between 1375 Hz and 20 10 Hz by electrically varying the elastic modulus of a magnetostrictive material. This operating principle is then implemented to obtain high bandwidth tunability in a Terfenol-D vibration absorber.

关键词： magnetostrictive effect realizable smart materials Elastic Modulus Magnetic saturation crystal lattices Electricity Short circuits vibration absorber Magnetostriction high-bandwidth

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Electrostrictive patches for active vibration control of thin plate host structures

Electrostrictive patches for active vibration control of thi...

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smart structures and materials 2000 Conference

作者： Pablo, F Petitjean, B Off Natl Etud & Rech Aerosp Struct Dynam & Coupled Syst Dept F-92322 Chatillon France

ISBN: (纸本)0819436038

Current applications in active vibration control mainly use piezoceramic actuators (PZT). With the aim of improving vibration absorption, electrostrictive actuators have been elaborated. These electrostrictive ceramics show very attractive properties for active vibration control applications. Yet, their non linear electromechanical behavior tempers these numerous advantages and considerably complicate their use, In usual active vibration control applications, dynamic electric fields with varying magnitudes and frequencies are applied to the ceramic. Earlier measurements, performed at ONERA, show that the ceramic behavior is strongly sensitive to operating parameters (electric field magnitude and excitation frequency, and surrounding temperature). It is demontrated in this article that this sensitivity can, in fact, be reduced to a sensitivity of the material to its own temperature. Indeed, a significant heating of electrostrictive ceramics occurs when they are subjected to a sinusoidal electric field. This heating turns out to be. itself, dependent on operating parameters. An experimental electric model of stressfree electrostrictive patches is presented, which is then used to develop constitutive relations of these materials. A simplified, dynamical, electromechanical coupled model of distributed electrostrictive patches bonded on a generic thin plate host structure is finally briefly discussed.

关键词： electrostrictive patches actuators active vibration control non linear material model coupled model

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Optimal piezo-actuator locations/lengths and applied voltage for shape control of beams

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smart materials & structures 2000年第2期9卷 205-211页

作者： Bruch, JC Sloss, JM Adali, S Sadek, IS Univ Calif Santa Barbara Dept Mech & Environm Engn Santa Barbara CA 93106 USA Univ Calif Santa Barbara Dept Math Santa Barbara CA 93106 USA Amer Univ Sharjah Dept Comp Sci Math & Stat Sharjah U Arab Emirates

Shape control of beams under general loading conditions is implemented using piezoceramic actuators to provide the control forces. The objective of the shape-control is to minimize the maximum deflection of the beam to obtain a min-max deflection configuration with respect to loading and piezo-actuators. In practice, the loading on a beam is a variable quantity with respect to its magnitude, and this aspect can be handled easily by optimizing the magnitude of the applied voltage to achieve the min-max deflection. This property of the smart materials technology overcomes the problem of one-off conventional optimal designs which become suboptimal when the loading magnitude changes. In addition to the magnitude of the applied voltage, the optimal values for the locations and the lengths of the piezo-actuators are determined to achieve the min-max deflection. Due to the complexity of the governing equations involving finite length piezo patches, the numerical results are obtained by the finite-difference method. The analysis of the problem shows the effect of the actuator locations, lengths and the applied voltage on the maximum deflection. The optimal Values for the actuator locations and the voltage are determined as functions of the load locations and load magnitudes, respectively. The effect of the actuator length on the min-max deflection is investigated and it is observed that the optimal length depends on the applied voltage. Finally, it is shown that using multiple actuators are more effective than a single actuator in the cases of complicated loading.

关键词： actuators loading magnitude applied voltage magnitude Shape control BEAM LOADING EARTHQUAKE MAGNITUDE Beams and girders Deflection Optimal maximum deflection

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Finite element/boundary element simulation of interior noise control using active-passive control technique

Finite element/boundary element simulation of interior noise...

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smart structures and materials 2000 - mathematics and control in smart structures

作者： Gopinathan, Senthil V. Varadan, Vasundara V. Varadan, Vijay K. Pennsylvania State Univ University Park PA United States

This paper presents a finite element/boundary element (FE/BE) formulation for modeling and analysis of active-passive noise control system. Finite element method is proposed to model the smart plate with surface bonded piezoelectric patches and the enclosing walls and the dual reciprocity boundary element method is proposed for modeling the acoustic cavity. The use of FE/BE method facilitates us imposing the impedance boundary conditions at the fluid/passive absorber/structure interface. An output feedback optimal controller design procedure is given for the smart plate system with active patches for the low frequency regime.

关键词： Acoustic variables control

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Boeing Active Flow control System

Boeing Active Flow Control System

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smart structures and materials 2000 - Industrial and Commercial Applications of smart structures Technologies

作者： Jacot, Dean Calkins, Tad Boeing Phantom Works

The Boeing Active Flow control (AFC) System (BAFCS) is a DARPA sponsored program to develop AFC technology to achieve a significant increase in payload for the V-22 tiltrotor vehicle. The program includes Computational Fluid Dynamics (CFD) analysis, wind tunnel testing and development of smart material based AFC actuators. This paper will provide an overview of the program and its interrelationships, as well as concentrating on the development of the AFC actuators.

关键词： Flow control

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Design and performance of a resonant roller wedge actuator

Design and performance of a resonant roller wedge actuator

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smart structures and materials 2000 Conference

作者： Frank, J Koopmann, GH Chen, WC Mockensturm, E Lesieutre, GA Penn State Univ Ctr Acoust & Vibrat University Pk PA 16802 USA

ISBN: (纸本)0819436038

A compact rotary motor driven by piezoelectric bimorph actuators was developed for applications in adaptive, conformable structures for flow control. Using a roller wedge (rotary roller clutch) as its central motion rectifying element, the actuator converts electrical power to mechanical power by way of a set of resonating bimorph/mass systems. With this type of resonant drive system, the output mechanical power of the actuator was dramatically improved over previous inchworm-type designs. Also the actuator cost was kept low by using commercial roller clutches and bimorph actuators instead of PZT stacks. Within an application size constraint of 4 x 4 x 1.75 inches, the unloaded speed was 600 RPM, the stall torque was 0.5 N-m, and the peak output power was nearly 4 warts. The motor is driven by a single frequency sinusoidal input, resulting in significant improvements of the cost, size and complexity over typical piezoelectric actuator drivers. Since the backlash of the roller clutch is a critical parameter in assessing the motor performance, an experimental study was performed to better understand its dynamics.

关键词： Actuators Ferroelectric materials Prototyping Magnetism Acoustics Amplifiers Ceramics Interfaces Laser induced plasma spectroscopy smart structures

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