Intelligent structures for aerospace - A technology overview and assessment
TL;DR: In this paper, the authors present an overview and assessment of the technology leading to the development of intelligent structures, which are those which incorporate actuators and sensors that are highly integrated into the structure and have structural functionality, as well as highly integrated control logic, signal conditioning and power amplification electronics.
Abstract: HIS article presents an overview and assessment of the technology leading to the development of intelligent structures. Intelligent structures are those which incorporate actuators and sensors that are highly integrated into the structure and have structural functionality, as well as highly integrated control logic, signal conditioning, and power amplification electronics. Such actuating, sensing, and signal processing elements are incorporated into a structure for the purpose of influencing its states or characteristics, be they mechanical, thermal, optical, chemical, electrical, or magnetic. For example, a mechanically intelligent structure is capable of altering both its mechanical states (its position or velocity) or its mechanical characteristics (its stiffness or damping). An optically intelligent structure could, for example, change color to match its background.17 Definition of Intelligent Structures Intelligent structures are a subset of a much larger field of research, as shown in Fig. I.123 Those structures which have actuators distributed throughout are defined as adaptive or, alternatively, actuated. Classical examples of such mechanically adaptive structures are conventional aircraft wings with articulated leading- and trailing-edge control surfaces and robotic systems with articulated manipulators and end effectors. More advanced examples currently in research include highly articulated adaptive space cranes. Structures which have sensors distributed throughout are a subset referred to as sensory. These structures have sensors which might detect displacements, strains or other mechanical states or properties, electromagnetic states or properties, temperature or heat flow, or the presence or accumulation of damage. Applications of this technology might include damage detection in long life structures, or embedded or conformal RF antennas within a structure. The overlap structures which contain both actuators and sensors (implicitly linked by closed-loop control) are referred to as controlled structures. Any structure whose properties or states can be influenced by the presence of a closed-loop control system is included in this category. A subset of controlled structures are active structures, distinguished from controlled structures by highly distributed actuators which have structural functionality and are part of the load bearing system.
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19 Nov 2012
TL;DR: This book focuses on structural health monitoring in the context of machine learning and includes case studies that review the technical literature and include case studies.
Abstract: This book focuses on structural health monitoring in the context of machine learning. The authors review the technical literature and include case studies. Chapters include: operational evaluation, sensing and data acquisition, introduction to probability and statistics, machine learning and statistical pattern recognition, and data prognosis.
998 citations
800 citations
TL;DR: In this paper, an inversion-based approach to compensate for hysteresis and vibrations in the piezodynamics has been proposed to improve both the accuracy and the speed of piezoactuators.
Abstract: Structural vibrations and hysteresis nonlinearities in piezoactuators have been fundamental limitations when using these actuators for high-speed precision-positioning applications. Positioning speed (bandwidth) is limited by structural vibrations, typically, to about one-tenth the fundamental vibrational frequency of the piezoprobe. Further, precision in positioning is limited by hysteresis nonlinearities, which can result in signie cant errors for large-range positioning applications. This paper shows that signie cant improvements in precision and bandwidth can be achieved by using an inversion-based approach to compensate for hysteresis and vibrations in the piezodynamics. Theapproach decouplestheinversion into 1 )inversion of thehysteresisnonlinearity and 2 )inversion ofthe structuraldynamics,toe ndaninputvoltageproe lethatachievesprecisiontracking ofa desiredpositiontrajectory. Theapproachisappliedtoapiezoactuator,andexperimentalresultsshowthatanorderofmagnitudeimprovement in positioning speed is achieved, while maintaining precision tracking of the desired position trajectory. I. Introduction P IEZOACTUATORS can achieve nanometer resolution positioning and are hence increasingly being used for ultraprecision positioning in aerospace applications, 1;2 vibration control, scanning probe microscopy for surface characterization, and nanofabrication. 3i5 Two major limitations of present positioning techniquesusing piezoactuatorsare 1 )lowoperating bandwidthdue to positioning errors caused by structural vibrations at high speeds and 2) low precision for relatively large-range displacements (due to errors caused by hysteresis nonlinearities ), resulting in restricted positioning range. This paper presents a method to improve both the accuracy and the speed of piezoactuators by using an inversionbased approach to e nd the voltage input to the piezoactuators that compensates for the hysteresis nonlinearities and the structural vibrations. This approach e rst decouples the system dynamics into two separate subsystems that model 1 ) the hysteresis nonlinearity
721 citations
TL;DR: In this paper, the advances and trends in the formulations and applications of the finite element modeling of adaptive structural elements are surveyed and discussed in a first attempt to survey and discuss the advances.
Abstract: This paper makes a first attempt to survey and discuss the advances and trends in the formulations and applications of the finite element modeling of adaptive structural elements. For most contributions, the specific assumptions, in particular those of electrical type, and the characteristics of the elements are precised. The informations are illustrated in tables and figures for helpful use by the researchers as well as the designers interested in this growing field of smart materials and structures. Focus is put on the development of adaptive piezoelectric finite elements only. However, papers on other applications and active systems are also listed for completeness purpose. In total, more than 100 papers were found in the open literature. Taking this number as a measure of research activity, trends and ideas for future research are identified and outlined. 7 2000 Elsevier Science Ltd. All rights reserved.
639 citations
Cites methods from "Intelligent structures for aerospac..."
...However, careful analysis of these survey papers and those on the relatively new ®eld of `intelligent' or smart materials and structures [26,76,77] indicates that the ®nite element modeling of adaptive structural elements does not retain the expected attention....
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TL;DR: A review of the current status of development of piezo materials can be found in this article, where a number of lead free piezo ceramics have been explored, such as BNT, BKT, KNN, and BZT-BCT.
Abstract: The growth of piezo science is phenomenal since the discovery of piezoelectricity in 1880. Among various piezoelectric materials, lead zirconate titanate (PZT) is a very popular and exhaustively studied piezo system which allows synthesis of large number of materials with wide range of properties due to formation of solid solutions over large range of Zr:Ti ratio. Also, this system accommodates wide range of dopants for modification of crystal structure. Due to this versatile nature, PZT has emerged as very popular among users and researchers worldwide. However, considering the toxicity of lead oxide, development of lead free piezo ceramics is encouraged in recent years. Some lead free piezo material systems such as BNT, BKT, KNN, BZT-BCT have been explored. However, development of lead free piezo devices and their performance in comparison with PZT devices are yet to be established. At this juncture, it was felt that an article reviewing the current status of development of piezo materials highlighting t...
340 citations
Cites methods from "Intelligent structures for aerospac..."
...The technology for development of PZT materials and devices are well established and proved as best material for various application such as (i) actuators and sensors for aerospace vibration control, (ii) sonar transducer for naval application, (iii) precision flow control (iv) fuel injector system, (v) vibration energy harvesting etc [77–82]....
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References
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TL;DR: In this paper, a scaling analysis is performed to demonstrate that the effectiveness of actuators is independent of the size of the structure and evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure.
Abstract: This work presents the analytic and experimental development of piezoelectric actuators as elements of intelligent structures, i.e., structures with highly distributed actuators, sensors, and processing networks. Static and dynamic analytic models are derived for segmented piezoelectric actuators that are either bonded to an elastic substructure or embedded in a laminated composite. These models lead to the ability to predict, a priori, the response of the structural member to a command voltage applied to the piezoelectric and give guidance as to the optimal location for actuator placement. A scaling analysis is performed to demonstrate that the effectiveness of piezoelectric actuators is independent of the size of the structure and to evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure. Three test specimens of cantilevered beams were constructed: an aluminum beam with surface-bonded actuators, a glass/epoxy beam with embedded actuators, and a graphite/epoxy beam with embedded actuators. The actuators were used to excite steady-state resonant vibrations in the cantilevered beams. The response of the specimens compared well with those predicted by the analytic models. Static tensile tests performed on glass/epoxy laminates indicated that the embedded actuator reduced the ultimate strength of the laminate by 20%, while not significantly affecting the global elastic modulus of the specimen.
2,719 citations
01 Jan 1982
TL;DR: The Review of Progress in Quantitative NDE (ROPQN) as mentioned in this paper is the world's leading conference in reporting annually new research and development results in quantitative NDE and promotes communication between the research and engineering communities and emphasize current reporting of work in progress.
Abstract: The Review of Progress in Quantitative NDE is the world's leading conference in reporting annually new research and development results in quantitative NDE. The conference reports on both fundamental and applied advances in NDE and promotes communication between the research and engineering communities and emphasize current reporting of work in progress. Attendees include representatives of academia (including students), industry, and government with approximately one-half coming from the United States and the other half from overseas. This volume represents the best report of ongoing work that is available anywhere. Connections and overlap with the medical diagnostic community are highlighted.
1,989 citations
TL;DR: In this paper, the authors investigated the possibility of dissipating mechanical energy with piezoelectric material shunted with passive electrical circuits, and derived the effective mechanical impedance for the piezolectric element shunted by an arbitrary circuit.
Abstract: The possibility of dissipating mechanical energy with piezoelectric material shunted with passive electrical circuits is investigated. The effective mechanical impedance for the piezoelectric element shunted by an arbitrary circuit is derived. The shunted piezoelectric is shown to possess frequency dependent stiffness and loss factor which are also dependent on the shunting circuit. The generally shunted model is specialized for two shunting circuits: the case of a resistor alone and that of a resistor and inductor. For resistive shunting, the material properties exhibit frequency dependence similar to viscoelastic materials, but are much stiffer and more independent of temperature. Shunting with a resistor and inductor introduces an electrical resonance, which can be optimally tuned to structural resonances in a manner analogous to a mechanical vibration arsorber. Techniques for analyzing systems which incorporate these shunting cases are presented and applied to a cantilevered beam experiment. The experimental results for both the resistive and resonant shunting circuits validate the shunted piezoelectric damping models.
1,685 citations
TL;DR: In this article, an active vibration damper for a cantilever beam was designed using a distributed-parameter actuator and distributedparameter control theory, and preliminary testing of the damper was performed on the first mode of the beam.
Abstract: An active vibration damper for a cantilever beam was designed using a distributed-parameter actuator and distributed-parameter control theory. The distributed-parameter actuator was a piezoelectric polymer, poly (vinylidene fluoride). Lyapunov's second method for distributed-parameter systems was used to design a control algorithm for the damper. If the angular velocity of the tip of the beam is known, all modes of the beam can be controlled simultaneously. Preliminary testing of the damper was performed on the first mode of the cantilever beam. A linear constant-gain controller and a nonlinear constant-amplitude controller were compared. The baseline loss factor of the first mode was 0.003 for large-amplitude vibrations (± 2 cm tip displacement) decreasing to 0.001 for small vibrations (±0.5 mm tip displacement). The constant-gain controller provided more than a factor of two increase in the modal damping with a feedback voltage limit of 200 V rms. With the same voltage limit, the constant-amplitude controller achieved the same damping as the constant-gain controller for large vibrations, but increased the modal loss factor by more than an order of magnitude to at least 0.040 for small vibration levels.
1,408 citations
TL;DR: In this article, a complete, unified, one-dimensional constitutive model of shape memory materials is developed and presented in the form of a thermomechanical model for shape memory alloys.
Abstract: The use of the thermoelastic martensitic transformation and its reverse transformation has recently been proposed and demonstrated for several active control ap plications. However, the present constitutive models have lacked several important funda mental concepts that are essential for many of the proposed intelligent material system ap plications such as shape memory hybrid composites.A complete, unified, one-dimensional constitutive model of shape memory materials is developed and presented in this paper. The thermomechanical model formulation herein will investigate important material characteristics involved with the internal phase transformation of shape memory alloys. These characteristics include energy dissipation in the material that governs the damping behavior, stress-strain-temperature relations for pseudoelasticity, and the shape memory effect. Some numerical examples using the model are also presented.
1,222 citations