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

作者： Fowler, Leslie P. Buchner, Steve Ryaboy, Vyacheslav Lord Corp Cary United States

High resolution metrology and production systems are pushing the capability of existing pneumatic isolation systems. The need for better isolation at low frequencies is growing as mechanical noise further constrains the lower limits of many electro-optical technologies and techniques. Unfortunately, the problem is magnified due to the 1-4 Hz natural frequency of pneumatic isolators. An active damping system, the ActivatorTM, uses an electromagnetic actuator to apply a damping force to an isolation table to reduce the transmission of these low amplitude, low frequency vibrations from the floor to the table. The system is low cost and easy to install. The controller, sensor, and electronics are integrated with the actuator. Given floor excitations on the order of submicrons, a 12 dB attenuation in transmissibility is achieved. This level of performance was attained after overcoming many physical hurdles due to the very low frequencies and small measurement signals (on the order of μg's). This unique, self-contained active damper results in a system more tolerant of existing floor locations and environments and is a simple upgrade, relieving the end user of facility improvements or relocation costs. This paper describes these challenges and shows how the performance goals were met while providing a compact, economical systems.

关键词： Vibration control

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Static, transient and modal sensitivity analysis using advanced solvers and massively parallel computing

Static, transient and modal sensitivity analysis using advan...

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41st structures, Structural Dynamics, and materials Conference and Exhibit 2000

作者： Alvin, Kenneth F. Reese, Garth M. Day, David M. Bhardwaj, Manoj K. Sandia National Laboratories Structural Dynamics Development Smart Systems Department P.O. Box 5800 Albuquerque NM 87185 United States Sandia National Laboratories Applied Mathematics Department Albuquerque NM 87185 United States

The sensitivity analysis capabilities of a newly-de-veloped general purpose finite element code for structural dynamics are described. The code, named Salinas, is designed to analyze structural models possessing millions or tens of millions of degrees of freedom using the latest distributed memory massively parallel processing technology. Sensitivity analysis has been an integral part of the code development effort and is available for static, dynamic, and modal analysis procedures. Implementation and performance issues are discussed, as well as new algorithms developed for the computation of eigenvector derivatives and the incorporation of modal damping into the direct, full-order implicit integration algorithm. Finally, performance results are presented for models ranging from one-half million to four million degrees of freedom and running on up to two thousand processors. © 2000 by Alvin et. al.

关键词： Sensitivity analysis

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structures Technology for Future Aerospace Systems

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丛书名： Progress in Astronautics and Aeronautics

2000年

作者： Ahmed K. Noor

ISBN: (数字)9781600866593

ISBN: (纸本)9781563473845

This new volume, edited by the director of the University of Virginia's Center for Advanced Computational Technology at NASA Langley Research Center, focuses on the component technologies that will play a major role in structures technology for future aerospace systems. Contributors use case histories to demonstrate the technology's development and carry it through to the current state of the art. Each chapter describes current capabilities, deficiencies, and barriers; current research activities; future directions of development; and applicability of the technology in the future,both near and far term.

关键词： Aeronautics Air Refueling Aircraft Components and Structure Aircraft Design Aircraft Operations and Technology Aircraft Wing Design Aircrafts Airfoil Airworthiness Astronomical Observatory Astronomy Aviation Aviation Authorities and Organizations Aviation Licenses and Certifications Aviation Safety Avionics Combat Aircraft Composite materials Composite structures Computational Fluid Dynamics Computer-Aided Design Coolant Cooling Technology Design for Manufacturing Electric Heating Failure Analysis Finite Element Method Finite Element Software Flexible and Active structures Fluid Dynamics Guidance, Navigation, and control Systems Heat Exchangers Heat Pipes Heating System Heating, Ventilating, and Air Conditioning Mass Transfer materials materials and Structural Mechanics Mechanical and Structural Vibrations Meteoroids Military Airbases Military Aircraft Military Aviation NASA Non-Combat Aircraft Numerical Analysis Planetary Rovers Planetary Science and Exploration Planets Rotorcrafts smart structures and materials Space Agencies Space Experiments Space Exploration and Technology Space Robot Space Science and Technology Space Telescopes Stress-Strain Analysis Structural Analysis Structural Design and Development Structural Engineering Structural Health Monitoring Structural Integrity Structural System structures, Design and Test Telescopes Thermal control and Protection Thermal Measurement Thermocouples Thermodynamic Properties Thermodynamics Thermophysics and Heat Transfer Trusses Unmanned Aerial Vehicle Vibration control Wing Configurations

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Shape memory alloys-their challenge to contribute to smart structures

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materials Research Society Symposium - Proceedings 2000年 604卷 87-98页

作者： Boller, C. DaimlerChrysler Aerospace Muenchen Germany

Shape memory alloys (SMA) have generated a lot of new ideas in engineering. Application is however so far limited to clamps and springs. With respect to smart structures sensing as well as control has to be included. While sensing looks to be relatively feasible control is the big challenge. This paper describes some aerospace related smart structures ideas using SMAs and discusses the challenges which need to be solved before these ideas have can be realised.

关键词： Shape memory effect

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Enhancement of the dynamic response characteristics of classical drives with smart actuators for high speed and precision machinery applications

Enhancement of the dynamic response characteristics of class...

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smart structures and materials 2000 - Active materials: Behavior and Mechanics

作者： Rastegar, Jahangir S. Yuan, Lifang Wang, Wenwei State Univ of New York at Stony Brook Stony Brook United States

One of the primary factors limiting the performance of high speed and precision computer controlled machinery such as robotic systems is the dynamic response limitation of their actuation mechanism. This is particularly the case when revolute joints are used in the construction of a machine, thereby resulting in systems with highly nonlinear dynamics. In such systems, even if the joint motion trajectories were synthesized with low harmonic contents, the actuating torques (forces) required for accurate tracking of the synthesized motions would contain high harmonic components. The higher harmonic components are generated due to the nonlinearity in the dynamics and kinematics of the system. As the operating speed of such machines is increased, the high harmonic component of the required actuating torques become more significant and at some point move beyond the dynamic response limitations (`bandwidth') of the main drives. The performance of the system would therefore start to degrade and vibration and control begins to become problematic. In this paper, a method is presented for minimizing the high harmonic components of the required actuating torques using smart materials based actuators. The effective dynamic response (`bandwidth') of the system drives is thereby enhanced. In this paper, the development of the general methodology is presented. The method is then applied to a plane 2R robot manipulator. The effectiveness of the proposed approach in reducing the higher harmonic components of the primary drives and thereby enhancing the performance of the system is illustrated by computer simulation.

关键词： Actuators

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Semi-active control of a thin piezoactuated structure

Semi-active control of a thin piezoactuated structure

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smart structures and materials 2000: Damping and Isolation

作者： Bisegna, Paolo Caruso, Giovanni Del Vescovo, Dionisio Galeani, Sergio Menini, Laura Univ Rome `Tor Vergata' Rome Italy

Vibration damping of a cantilever plate is achieved by using a piezoelectric element simultaneously as passive single-mode device and active broad-band actuator. control strategies are designed on the basis of a modal model of the coupled electro-mechanical structure. This model is obtained by using a suitable finite-element formulation together with a modal analysis. A purely passive single-mode control composed of an optimally tuned external RL shunt circuit and a purely active control based on classical LQG techniques are compared to a semi-active control obtained by tuning the external shunt circuit on the second vibration mode of the structure and using a LQG controller designed on the only first-mode model.

关键词： Structural analysis

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MicroElectroMechanical System (MEMS)-Based Fiber Optic Grating Sensor for improving weapon stabilization and fire control

MicroElectroMechanical System (MEMS)-Based Fiber Optic Grati...

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smart structures and materials 2000 - smart Electronics and MEMS

作者： Zhang, Sean Z. Xu, Guoda Qiu, Wei Lin, Freddie Testa, Robert C. Mattice, Michael S. Physical Optics Corp Torrance United States

A MicroElectroMechanical System (MEMS)-Based Fiber Optic Grating Sensor (FOGS) for improving weapon stabilization and fire control has been investigated and developed. The technique overwrites two fiber Bragg gratings (FBGs) onto a polarization-preserving optical fiber core. A MEMS diaphragm is fabricated and integrated with the overlaid FBGs to enhance the performance and reliability of the sensor. A simulation model for the MEMS-FOGS was derived, and simulation results concerning load, angle, strain, and temperature were obtained. The fabricated MEMS diaphragm and the overlaid FBGs are packaged together and mounted on a specially designed cantilever beam system. User-friendly software for sensing system design and data analysis has been developed and can be used to control other sensing systems. The combined multifunctional MEMS-FOGS is cost-effective, quick, rugged enough to withstand harsh environmental conditions, compact, and highly sensitive. The fully developed sensing system is expected to find applications in fire control, weapon stabilization, and other areas where accurately sensing strain and temperature is critical.

关键词： Microsensors

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An investigation of piezoelectric smart composites using a coupled piezoelectric-mechanical model

An investigation of piezoelectric smart composites using a c...

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AIAA/ASME/ASCE/AHS/ASC 41st structures, Structural Dynamics, and materials Conference

作者： Zhou, X Chattopadhyay, A Thornburgh, R Arizona State Univ Dept Mech & Aerosp Engn Tempe AZ 85287 USA

A two-way piezoelectric-mechanical coupled theory is used to investigate the multiple field interactions of composite laminates with surface-bonded piezoelectric actuators and sensors. A higher order electrical potential field is used to accurately describe the nonuniform distribution of electric potential through the thickness of piezoelectric layers. A higher order laminate theory is used to describe the displacement fields of both composite laminate and piezoelectric layers to accurately model transverse shear deformation which is significant in moderately thick constructions. A finite element model is developed to implement the theory. The results obtained using this coupled theory are compared with those obtained using an uncoupled theory. Numerical results indicate that the thickness ratio of piezoelectric layer to plate structure is a critical parameter that determines the significance of coupling effects. The coupled piezoelectric-mechanical theory is capable of accurately modeling the characteristics of thick piezoelectric layers. Furthermore, the effects on multiple actuators, sensors and control authority due to the two-way coupling are also studied.

关键词： Electric potential

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Adaptive Blade Twist -: calculations and experimental results

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AEROSPACE SCIENCE AND TECHNOLOGY 2000年第5期4卷 309-319页

作者： Büter, A Breitbach, E German Aerosp Ctr DLR Inst Struct Mech D-38108 Braunschweig Germany

Applying adaptronics to helicopters has a high potential to significantly suppress noise, reduce vibration, and increase the overall aerodynamic efficiency. This paper presents recent investigations on a very promising specific concept described as Adaptive Blade Twist (ABT). This concept allows us to directly control the twist of the helicopter blades by smart adaptive elements. This influences positively the main rotor area which is the primary source for helicopter noise and vibration. Since the interaction of non-stationary helicopter aerodynamics and elastomechanical structural characteristics of the helicopter blades causes flight envelope limitations, vibration and noise, a good comprehension of the aerodynamics is essential for the development of structural solutions to effectively influence the local airflow conditions and finally develop the structural concept. With respect to these considerations, the ABT concept will be presented. This concept is based on the actively controlled tension-torsion-coupling of the structure. For this, an actuator is integrated within a helicopter blade that is made of an anisotropic material based on fiber composites. Driving the actuator results in a local twist of the blade tip in such a way that the blade can be considered as a torsional actuator. Influencing the blade twist distribution finally results in a higher aerodynamic efficiency. The paper starts at giving a review on conventional concepts and potential adaptive solutions for shape control. After, some calculations of the adaptive twist control concept are presented. These are based on a representative model in which the active part of the rotor blade is simplified with a thin-walled rectangular beam, that is structurally equivalent to a model rotor blade of the Bo105 with a scaling factor 2.54. The calculations are performed using an expanded Wlassow theory. The results are valid for static and dynamic conditions. For the dynamic condition excessive deformations

关键词： adaptive rotor systems adaptive rotor control adaptive materials and structures

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control of a dynamic vibration absorber with magnetorheological damping

Control of a dynamic vibration absorber with magnetorheologi...

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5TH European Conference on smart structures and materials

作者： Vavreck, Andrew N. Pennsylvania State Univ Altoona United States

Two control techniques are explored analytically for a dynamic vibration absorber with a magnetorheological fluid damper replacing the absorber dashpot. The approaches include skyhook control and an approximation to a linear quadratic optimal control. The approximate-optimal control, which attempts to match the magnetorheological damper force to an optimal control force based on a linear absorber, is shown to improve the dynamic absorber performance over a substantial range of excitation frequencies and force levels, while the skyhook approach is less successful. Detuning of the absorber natural frequency below the optimal detuning for a linear absorber improves performance in the approximate-optimal case.

关键词： Vibration control

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