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Passive Damping Conference

作者： BAZ, A RO, J CATHOLIC UNIV AMER DEPT MECH ENGNWASHINGTONDC 20064

ISBN: (纸本)0819414883

Theoretical and experimental performance characteristics of the new class of actively controlled constrained layer damping (ACLD) treatment are presented. The ACLD under consideration consists of a visco-elastic damping layer which is sandwiched between two piezo-electric layers. The three-layer composite ACLD when bonded to a vibrating structure acts as a smart constraining layer damping treatment with built-in sensing and actuation capabilities. Particular emphasis is placed on studying the performance of ACLD treatments that are provided with sensing layers of different spatial distributions. The effect of the modal weighting characteristics of these sensing layers on the broad band attenuation of the vibration of beams that are fully treated with the ACLD is presented theoretically and experimentally. The equations governing the operation of ACLD treatments with modally shaped sensors are presented. The theoretical predictions of the model are compared with the experimental performance of a computer-controlled beam treated with Dyad 606 visco-elastic layer sandwiched between two layers of polyvinylidene fluoride (PVDF) piezo-electric films. Comparisons with the performance of conventional passive constrained layer damping are also presented.

关键词： Sensors control systems Beam shaping Signal attenuation Actuators Ferroelectric polymers Finite element methods Amplifiers Performance modeling Composites

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ACTIVE control USING PIEZOCERAMIC LINEAR MOTORS

ACTIVE CONTROL USING PIEZOCERAMIC LINEAR MOTORS

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Passive Damping Conference

作者： HOLCOMB, MD POKINES, B INMAN, DJ SUNY BUFFALO BUFFALONY 14260

ISBN: (纸本)0819414883

Proof mass actuators have long been an accepted and reliable method of vibration control. With the advent of new piezoceramic technology, the proof mass can now be driven by a piezoceramic linear motor. A linear motor has been designed and its performance is evaluated by comparing it against a Physik Instrument piezoceramic stack translator. Both linear motors are used to actively add damping to the bending modes of a section of the NASA Phase Zero Evolutionary Model. A modal test has been done on the test structure and its mode shapes, natural frequencies and damping ratios have been recorded. In the unlikely event of a power failure on board such a structure, a backup control scheme is desired. Viscoelastic damping material is incorporated into the newly designed actuator to improve the stability of the closed loop system and to offer good `shut down' performance in case of a power failure. Actuator performance such as force output, stroke length, and control implementation are compared.

关键词： Actuators Linear filtering Interference (communication) Sensors Aluminum Ceramics Signal attenuation control systems Manufacturing Molecules

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ACTUATOR WITH BUILT-IN VISCOUS DAMPING FOR ISOLATION AND STRUCTURAL control

ACTUATOR WITH BUILT-IN VISCOUS DAMPING FOR ISOLATION AND STR...

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Passive Damping Conference

作者： HYDE, TT ANDERSON, EH MIT DEPT AERONAUT & ASTRONAUTSPACE ENGN RES CTRCAMBRIDGEMA 02139

ISBN: (纸本)0819414883

This paper describes the development and experimental application of an actuator with built-in viscous damping. An existing passive damper was modified for use as a novel actuation device for isolation and structural control. The device functions by using the same fluid for viscous damping and as a hydraulic lever for a voice coil actuator. Applications for such an actuator include structural control and active isolation. Lumped parameter models capturing structural and fluid effects are presented. Component tests of free stroke, blocked force, and passive complex stiffness are used to update the assumed model parameters. The structural damping effectiveness of the new actuator is shown to be that of a regular D-strut passively and that of a piezoelectric strut with load cell feedback actively in a complex testbed structure. Open and closed loop results are presented for a force isolation application showing an 8 dB passive and 20 dB active improvement over an undamped mount. An optimized design for a future experimental testbed is developed.

关键词： Actuators Interferometers control systems Solids Active isolation Optical isolators Vibration isolation Aluminum Passive elements Passive isolation

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Optimal design of fiber optic sensors for control of flexible structures

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smart materials and structures 1994年第4期3卷 397-408页

作者： Meng, C.-L. Gibson, J.S. Mechanical Aerospace and Nuclear Engineering University of California Los Angeles CA 90024-1597 United States

This paper presents methods for designing fiber optic sensors for control of flexible structures. The sensors are designed so that a first-order observer, instead of a high-order state estimator, can be used to construct feedback control laws based on distributed or high-order finite-dimensional models of the structure. Design methods for the sensors and the observers are developed for two types of problems: first where the sensors extend over the entire structure, and second, where the sensors extend over one or more subregions. © 1994 IOP Publishing Ltd.

关键词： Fiber optic sensors

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RELATING THE COMPLEX MODULI OF VISCOELASTIC materials TO THE COMPLEX STIFFNESS OF ANTI-VIBRATION MOUNTS

RELATING THE COMPLEX MODULI OF VISCOELASTIC MATERIALS TO THE...

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Passive Damping Conference

作者： OYADIJI, SO TOMLINSON, GR UNIV MANCHESTER DEPT ENGNDYNAM & CONTROL RES GRPMANCHESTER M13 9PLLANCSENGLAND

ISBN: (纸本)0819414883

Analytical and empirical expressions that relate the complex dynamic stiffness of an elastomeric or viscoelastic anti-vibration mount to the complex Young's modulus of the constituent elastomeric or viscoelastic material of the mount are presented. These expressions incorporate the geometrical dimensions of the mount, the shape factor effects, and the non- linear deflection characteristics of the mount. It is shown that the use of these expressions, in conjunction with the complex Young's modulus of the constituent viscoelastic material, yields accurate predictions of the complex dynamic stiffness characteristics of an anti-vibration mount which was subjected to static prestrain levels of between 0% and 30% and was tested over a wide temperature range of -50 degree(s)C to 100 degree(s)C. Furthermore, it is shown that the master curves of complex dynamic stiffness predicted for the anti-vibration mount at static prestrain levels of 10% to 20% correlate fairly well with the master curves of complex dynamic stiffness derived from measured data using the temperature-frequency superposition principle.

关键词： Superposition Temperature metrology Polymers Actuators Analytical research Crystals Electrodynamics Roads Solids

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Self-sensing control as applied to a PZT stack actuator used as a micropositioner

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smart materials and structures 1994年第2期3卷 147-156页

作者： Jones, Lowell Garcia, Ephrahim Waites, Henry Smart Structures Laboratory Department of Mechanical Engineering Vanderbilt University Box 1592 Station B Nashville TN 37235 United States Controls and Pointing Branch ED-12 Marshall Space Flight Center MSFC AL 35812 United States

Recently, more attention has been focused on improving open-loop performance characteristics of smart actuator materials. The impetus in pursuing this course of research is reducing the need for often costly and obtrusive independent sensors used for feedback to the actuator. Self-sensing actuation is a control technique that can be applied to many smart materials including piezoceramics. It involves extracting a sensing signal from the actuating material by use of a bridge circuit, then properly feeding this signal back to improve the actuator's performance. The research presented in this paper is concerned with the feasibility of applying this technique to a soft PZT stacked actuator used as a micropositioner. The result of applying this control technique was a reduction of the micropositioner's decay time from over 1 ms to under 0.3 ms. A major contributor to the success of this research was the insertion of a nonlinear element in the self-sensing bridge which negated the nonlinear effects of the PZT stack thus enabling an increase in the self-sensing signal-to-noise ratio. © 1994 IOP Publishing Ltd.

关键词： Actuators

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A simulated annealing technique for multiobjective optimization of intelligent structures

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smart materials and structures 1994年第2期3卷 98-106页

作者： Chattopadhyay, Aditi Seeley, Charles E. Department of Mechanical and Aerospace Engineering Arizona State University Tempe AZ 85287 United States

A multiobjective optimization procedure is developed to address the combined problems of the synthesis of structures/controls and the actuator-location problem for the design of intelligent structures. Continuous and discrete variables are treated equally in the formulation. Multiple and conflicting design objectives such as vibration reduction, dissipated energy, power and a performance index are included by utilizing an efficient multiobjective optimization formulation. Piezoelectric materials are used as actuators in the control system. A simulated annealing algorithm is used for optimization and an approximation technique is used to reduce computational effort. A numerical example using a cantilever box beam demonstrates the utility of the optimization procedure when compared with a previous nonlinear programming technique. © 1994 IOP Publishing Ltd.

关键词： Multiobjective optimization

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DEMONSTRATION OF SOLAR-ARRAY VIBRATION SUPPRESSION

DEMONSTRATION OF SOLAR-ARRAY VIBRATION SUPPRESSION

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Passive Damping Conference

作者： KIENHOLZ, DA PENDLETON, SC RICHARDS, KE MORGENTHALER, DR CSA ENGN INC PALO ALTOCA

ISBN: (纸本)0819414883

An adaptive passive damping system is described for the low-order modes of spacecraft large solar arrays. The work is motivated by the stringent sensor pointing requirements of several current satellite programs. Realistic system-level requirements are developed relating pointing error of a representative spacecraft to damping of its solar arrays. Performance is specified in terms of gain envelopes on open-loop frequency response functions for the structure with dampers. A family of remotely tunable, eddy-current tuned mass dampers (TMDs) is described which suppress several modes of a 430-lb solar array simulator in the frequency range of 0.1 - 1.0 Hz. The magnetic dampers are ground demonstration units, suitable for use in 1-G, but are designed around traceable, system-level dynamic requirements. The damper design is intended from the outset to be evolved into flight hardware. Tuning of TMD natural frequency and damping ratio to their optimum values is demonstrated through component-level base transmissibility test results.

关键词： Magnetism Space operations Sensors Target designation Reliability Signal attenuation Astronomical engineering control systems control systems design Satellites

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JITTER SUPPRESSION EXPERIMENT PASSIVE DAMPING DESIGN CYCLE

JITTER SUPPRESSION EXPERIMENT PASSIVE DAMPING DESIGN CYCLE

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Passive Damping Conference

作者： DRAKE, ML FRANK, GJ OLSON, SE UNIV DAYTON RES INSTDAYTONOH 45469

ISBN: (纸本)0819414883

The University of Dayton Research Institute is teamed with McDonnell Douglas Aerospace to develop and fly a NASA IN-STEP experiment entitled Jitter Suppression Experiment (JSX). The JSX will demonstrate a combined active/passive vibration control system on an actual full scale space structure. This paper presents the details of the design of the passive control system to be applied to six graphite/epoxy support tubes for a gimballed telescope assembly (GTA) and the results of concept development laboratory tests. The most promising damping concepts for tubes such as the GTA truss tubes were constrained layer dampers and tuned dampers. The advantages and disadvantages of each of these damping concepts and the reasons for choosing a constrained layer concept are discussed. To verify the effectiveness of the passive damping design and to determine the constrained layer damping system effectiveness for axial modes, a finite element analysis of a single truss tube with the proposed constraining layer design was performed. A laboratory simulation was designed, developed, and evaluated to verify the analysis.

关键词： control systems design Space telescopes Temperature metrology Finite element methods Systems modeling Telescopes Vibration control Aluminum Aerospace engineering control systems

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Fatigue damage control of mechanical systems

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smart materials and structures 1994年第1期3卷 47-58页

作者： Ray, Asok Wu, Min-Kuang Pennsylvania State Univ University Park United States

This paper presents the concept and architecture of a fatigue damage control system for mechanical structures. In contrast to the conventional cycle-based approach, fatigue damage is represented via non-linear differential equations with respect to time in the state-variable setting. This damage model is compatible with the dynamic model of the plant, i.e. the process under operation and control, and the instantaneous damage rate depends on the current level of accumulated damage. The objective here is to achieve an optimized trade-off between dynamic performance and structural durability of the plant. This interdisciplinary effort requires augmentation of the system-theoretic techniques for decision making and control with governing equations and inequality constraints representing the fatigue damage properties of structural materials. The major challenge in the reported work is to characterize the fatigue damage generation process in mechanical structures and then utilize this information for synthesizing algorithms of performance optimization, robust control and risk assessment for plant operation.

关键词： Fatigue of materials

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