This paper presents a novel integrated formulation and robust computational tool that can be efficiently employed for the design and analysis of actively controlled smart composite structural systems. The modeling sim...
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ISBN:
(纸本)0819427675
This paper presents a novel integrated formulation and robust computational tool that can be efficiently employed for the design and analysis of actively controlled smart composite structural systems. The modeling simulation capabilities account for the coupling between thermal, mechanical and electric fields within the framework of an integrated structure/control strategy. The paper also reports the formulation and implementation of an optimization capability for the design and tailoring of smart structural systems. Finally, probabilistic and fuzzy models for rationally and systematically accounting for the uncertainties in structural, control, material, and load parameters are presented. The capabilities are packaged in a comprehensive and user-friendly software system (smartCOM) that can be readily applied for cost-effective design or response characterization of actively controlled smartstructures.
In this paper we consider the problem of deployment of tensegrity structures. Our idea is to make use of a certain set of equilibria to which the undeployed and deployed configurations belong. In the state space this ...
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ISBN:
(纸本)0819427675
In this paper we consider the problem of deployment of tensegrity structures. Our idea is to make use of a certain set of equilibria to which the undeployed and deployed configurations belong. In the state space this set is represented by a connected equilibrium manifold and can be completely characterized analytically. The deployment is conducted such that the deployment trajectory is close to the equilibrium manifold and the deployment time is minimized.
The paper gives an outline of a recent research program on smartstructures at the University of Stuttgart in which 16 research projects have been combined. The program is expected to last about 10 years. The covered ...
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The paper gives an outline of a recent research program on smartstructures at the University of Stuttgart in which 16 research projects have been combined. The program is expected to last about 10 years. The covered fields range from smartmaterials and their integration into composites to shape adaptation of aircraft wings, active vibration suppression and noise control. The program is initiated by the university, supported by the German Research Foundation, and designed in coordination to related industrial projects.
Tensegrity structures represent a special class of tendon space structures, whose members may simultaneously perform the functions of strength, sensing, actuating and feedback control. The paper exploits this advantag...
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ISBN:
(纸本)0819427675
Tensegrity structures represent a special class of tendon space structures, whose members may simultaneously perform the functions of strength, sensing, actuating and feedback control. The paper exploits this advantage, proposing a smart tensegrity sensor for simultaneous measurement of six quantities: three orthogonal forces and three orthogonal moments. The paper shows how the static and dynamic characteristics of the device can be calibrated through pretension and damping adjustment. The external forces and torques of interest are estimated using the measurements provided by selected tendons. A state estimator, based on the linearized model, finalizes the design.
The use of smartmaterials (piezoceramic elements) in structure vibration damping has risen in popularity. The ability to use these materials as both sensors, capturing a voltage upon straining of the material, and ac...
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ISBN:
(纸本)0819427675
The use of smartmaterials (piezoceramic elements) in structure vibration damping has risen in popularity. The ability to use these materials as both sensors, capturing a voltage upon straining of the material, and actuators, acquiring a displacement due to an electric voltage, has increased The work presented in this paper develops the use of robust intelligent control as applied to smartmaterials. A steel cantilever beam was constructed as the experimental (physical) plant. Piezoceramic material, lead zirconate titanate (PZT), was surface mounted as both sensors and actuators. The controller was formed using algorithms produced from adaptive fuzzy controls. Fuzzy model reference learning control (FMRLC) is a learning system with the capability to improve its performance over a period of time when various plant uncertainties are introduced. The expected goal of this paper is to dampen the fundamental vibration mode of the beam utilizing the intelligent control algorithm developed. Other controllers, such as positive position feedback (PPF) and direct fuzzy (DF), were developed and compared to the adaptive fuzzy controller. The robustness of the system was also examined when the cantilever beam system properties changed. Extra masses were added to account for the variations of the system parameters. The FMRLC controller showed a dramatic improvement over the PPF and the DF. It is the adaptive nature of the FMRLC that makes the system robust to parameter changes.
The problem of controlling the dynamic response of cantilevers exposed to blast loading is addressed. The structure to be controlled consists of a thin-walled beam of a closed cross-section contour which encompasses a...
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ISBN:
(纸本)0819427675
The problem of controlling the dynamic response of cantilevers exposed to blast loading is addressed. The structure to be controlled consists of a thin-walled beam of a closed cross-section contour which encompasses a number of non-classical features such as transverse shear, primary and secondary warping and anisotropy of the constitutent materials. The control is achieved via the use of the directionality property featured by advanced composite materials and of the actuating capabilities provided by piezoelectric devices which are bonded or embedded into the host structure. The cases of the 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 the patch location upon the control efficiency are discussed. Other issues related with the minimization of the input power required, and implications of the limitation of control input voltage are also addressed.
This paper is devoted to the dynamic modeling and control of multilayered smart beams of solid cross-section with surface-bonded piezoactuator layers. In contrast to the classical assumption of the perfect bonding of ...
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ISBN:
(纸本)0819427675
This paper is devoted to the dynamic modeling and control of multilayered smart beams of solid cross-section with surface-bonded piezoactuator layers. In contrast to the classical assumption of the perfect bonding of constituent layers, herein the existence of interfacial bonding imperfections among the layers of the host structure is stipulated. The requirements of shear traction continuity and displacement jump across each interface are used to model structures featuring imperfect bonding. Their implications on free and forced vibration control is analyzed via a combined dynamic feedback control law relating the piezoelectrically induced bending moment at the beam tip with the various kinematic response quantities. Numerical results for cantilever adaptive beams experiencing flexural motion under transient distributed loading are presented. For the case of an out-of-phase electrical activation of the smart structure, implications of the interface bonding imperfections on the structural quantities are investigated. The obtained results reveal the powerful role played by the proposed control methodology towards enhancing the dynamic response of cantilevered multilayered anisotropic beams to transient loadings. Also, the results are likely to contribute to a better understanding and reliable design of smartstructures featuring interfacial bonding imperfections.
The objective of this paper is to describe the development of an analytical closed form solution to model a composite adaptive plate with embedded or bonded piezoelectric actuators and sensors. The mathematical model ...
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ISBN:
(纸本)0819427675
The objective of this paper is to describe the development of an analytical closed form solution to model a composite adaptive plate with embedded or bonded piezoelectric actuators and sensors. The mathematical model which describes the electromechanical coupling, the equations of motion and the boundary conditions is based on the Mindlin displacement field and on the Hamilton principle. The electromechanical coupling is a consequence of the piezoelectric characteristics of the actuator and sensor materials. This mathematical modelling technique for distributed actuators and sensors embedded in a composite adaptive plate is based on the Heaviside function.
Photo-resist dispensers traditionally apply a generous amount of resist on the wafer and then spin the wafer to reach a uniform desired thickness. With this technique, over 95% of expensive and hazardous liquid is was...
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ISBN:
(纸本)0819427675
Photo-resist dispensers traditionally apply a generous amount of resist on the wafer and then spin the wafer to reach a uniform desired thickness. With this technique, over 95% of expensive and hazardous liquid is wasted. The goal of this project is to reduce the waste by using a drop-on-demand ejection technology to apply the photo-resist. In practice, a controller turns out to be necessary to compensate for the variability of the performance of the ejectors, to insure the stability of the ejection, and to speed up the transient regime for drop-on-demand operation. This paper reports on the design and simulation of this controller.
control of vibration of a base excited cantilever 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 caused b...
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ISBN:
(纸本)0819427675
control of vibration of a base excited cantilever 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 caused by external excitation can be annihilated by a control wave of opposite signature. Collocated sensor and actuator are used to sensing the traveling wave and generating the control wave. Experimental and numerical results showed that the vibration of a cantilevered beam is substantially suppressed.
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