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Showing papers on "Smart material published in 1998"


Journal ArticleDOI
TL;DR: A review of shape-memory materials can be found in this paper, where the basic phenomena in the materials, that is, the stimulus-induced phase transformations which result in the unique performance and govern the remarkable changes in properties of the materials are systematically lineated.
Abstract: A review is presented of the current research and development of shape-memory materials, including shape-memory alloys, shape-memory ceramics and shape-memory polymers. The shape-memory materials exhibit some novel performances, such as sensoring (thermal, stress or field), large-stroke actuation, high damping, adaptive responses, shape memory and superelasticity capability, which can be utilized in various engineering approaches to smart systems. Based on an extensive literature survey, the various shape-memory materials are outlined, with special attention to the recently developed or emerged materials. The basic phenomena in the materials, that is, the stimulus-induced phase transformations which result in the unique performance and govern the remarkable changes in properties of the materials, are systematically lineated. The remaining technical barriers, and the challenges to improve the present materials system and develop a new shape memory materials are discussed.

542 citations


Journal ArticleDOI
TL;DR: In this article, a passive smart-healing cementitious composite has been demonstrated, in the laboratory, to be feasible, to demonstrate the basic elements of this smart material include the sensors and actuators in the form of controlled microcracks and hollow glass fibers carrying air-curing chemicals.
Abstract: The basic concept of a passive smart-healing cementitious composite has been demonstrated, in the laboratory, to be feasible. The basic elements of this smart material include the sensors and actuators in the form of controlled microcracks and hollow glass fibers carrying air-curing chemicals. Controlled microcracking is offered by a strain-hardening engineered cementitious composite developed previously. The mechanisms of sensing and actuation are revealed through in situ environmental scanning electron microscopy observations. The self-healing effectiveness is confirmed by measurement of the elastic modulus of the composite. The elastic modulus is found to regain its original value in a repeat loading subsequent to damage in a first load cycle.

347 citations


Journal ArticleDOI
TL;DR: In this article, a survey of shape-memory hybrid smart composites is presented, with a focus on the design, fabrication, characterization and performance of fiber-reinforced, particle reinforced, and multi-layered thin-film shape memory composites.
Abstract: By hybridizing or incorporating shape-memory materials with other functional materials or structural materials, smart composites can be fabricated which may utilize the unique functions or properties of the individual bulk materials to achieve multiple responses and optimal properties, or, to tune their properties to adapt to environmental changes. A variety of shape-memory hybrid composites have been designed and manufactured, with shape-memory elements being either the matrix or the reinforcement. The hybrid composites provide tremendous potential for creating new paradigms for material–structural interactions and demonstrate varying success in many engineering applications. This review, from the standpoint of materials science, will give a state-of-the-art survey on the various shape-memory hybrid smart composites developed during the last decade. Emphasis is placed on the design, fabrication, characterization and performance of fibre-reinforced, particle-reinforced and multi-layered thin-film shape-memory composites.

258 citations


Journal ArticleDOI
TL;DR: This article is specifically focused on the application of piezoelectric materials, magnetostrictive materials and shape memory alloys to intelligent material systems used to control the deformation, vibration and fracture of composite materials and structures.
Abstract: This article presents a review of recent important developments in the field of intelligent material systems. Intelligent material systems, sometimes referred to as smart materials, can adjust their behavior to changes of external or internal parameters analogously to biological systems. In these systems, sensors, actuators and controllers are seamlessly integrated with structural materials at the macroscopic or mesoscopic level. In general, sensors and actuators are made of functional materials and fluids such as piezoelectric materials, magnetostrictive materials, shape memory alloys, polymer hydrogels, electro- and magneto-rheological fluids and so on. This article is specifically focused on the application of piezoelectric materials, magnetostrictive materials and shape memory alloys to intelligent material systems used to control the deformation, vibration and fracture of composite materials and structures. This review article contains 188 references.

186 citations


Journal ArticleDOI
TL;DR: In this article, shape-memory effect in nickel-titanium (nitinol) alloy was successfully utilized as a way of inducing additional prestressing in concrete, where wires made with SMA wires were electrically actuated to induce deflection and failure in concrete (mortar) beams.
Abstract: Shape-memory effect in nickel-titanium (nitinol) alloy was successfully utilized as a way of inducing additional prestressing in concrete. Strands made with NiTi (nickel/titanium) shape-memory alloy (SMA) wires were elongated beyond their plastic limit and subsequently were embedded in model concrete (mortar) beams. Upon electrical heating, a martensite-to-austenite phase transformation takes place and the material undergoes large shrinkage strains. This strain energy can be used to generate a significant prestressing force in concrete. Potentially, this provides a means of creating a “smart bridge,” where the amount of prestress can be increased or decreased as needed. Such a structure could actively accommodate additional loading, or remedy prestress losses over time. Properties of the SMA material and the micromechanics of its bond with concrete were investigated. Strands made with SMA wires were electrically actuated to induce deflection and failure in concrete (mortar) beams. Optical microscopy and t...

140 citations


Journal ArticleDOI
TL;DR: In this paper, three case studies intending to apply smart materials to civil structures are presented, and the relationship between electrical resistance and strain of shape memory alloy wire is studied and the maximum strain of the specimen which is regarded as a structural member is estimated.
Abstract: In this paper, three case studies intending to apply smart materials to civil structures are presented. The first one is a study of response control using piezoelectric actuators. Actuators are inserted into the bottom of a column to produce a bending moment force. A control algorithm using the model matching method is introduced, and this algorithm is checked in shaking table tests of a four story frame. The second one is damage sensing of a structural member, using electric resistance characteristics of shape memory alloys. The relationship between electrical resistance and strain of shape memory alloy wire is studied and the maximum strain of the specimen which is regarded as a structural member is estimated. The third one is an energy dissipation device using super-elastic characteristics of a shape memory alloy. A basic energy dissipation device model using nitinol wire is proposed. The energy dissipation capacity is investigated by device tests, and an analytical model is constructed based on the test results.

105 citations


Book
01 Jan 1998
TL;DR: In this article, the sections in this article are==================@@@@@@@@@@@@@@@@@@@@@@@@````````````ÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂÃÂ````````▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
Abstract: The sections in this article are 1 Metallic Materials 2 Ceramics 3 Semiconductors 4 Polymers 5 Composite Materials 6 Other Materials 7 Acknowledgments

90 citations


Journal ArticleDOI
TL;DR: In this paper, a unique microamplification mechanism formed through the merging of smart material and microelectromechanical system concepts is presented, which is a radically scaled version of a mesoscopic mechanism.
Abstract: A unique microamplification mechanism formed through the merging of smart material and microelectromechanical system concepts is presented. This microamplification device increases the useful actuation stroke of piezoceramic material through the amplification of piezoceramic strain. The technology demonstrated has utility as a microactuation mechanism for driving micropiezomotors, hearing aid transducers and precision optical switches. The microamplifier, approximately , is composed of electroplated nickel and was constructed using LIGA. An overview of microactuator system requirements and the advantages of scaling the flexure based amplifier illustrates the utility of the new device. The microamplifier is a radically scaled version of a mesoscopic mechanism. An analytical discussion of the operation is presented along with a finite-element analysis of the static and dynamic properties of the microlever. The analytical study is used to develop the operation principles and expected performance of the microamplifier. Experimental static and dynamic testing results are presented that confirm the analytical study. The mechanism has a mean amplification ratio of 5.48, an elastic stroke range of 8 m and a fundamental frequency of 82 kHz.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of the film thickness and the cure temperature on the poling behavior of the PZT/epoxy paint film were analyzed with respect to the sensitivities as vibration and acoustic emission sensors in the frequency ranges of 0-250 Hz and 0-1.0 MHz.
Abstract: Piezoelectric paints have a potential to change a conventional structural material into an intelligent material system with health-monitoring capabilities such as vibration sensing and damage detection. Such paints were prepared using lead zirconate titanate (PZT) ceramic powder as a pigment and epoxy resin as a binder. The obtained paints were coated on aluminum test specimens, and were cured at room temperature or at 150 , thus forming the paint films having different thicknesses of 25-300 . These films were then poled at room temperature, and were evaluated with regard to the sensitivities as vibration and acoustic emission sensors in the frequency ranges of 0-250 Hz and 0-1.0 MHz, respectively. This paper mainly describes the effects of the film thickness and the cure temperature on the poling behavior of the PZT/epoxy paint film. This paper describes also the application of the paint film as a vibration modal sensor integrated into a structural material.

69 citations


Journal ArticleDOI
TL;DR: In this article, the authors introduce the shock and vibration community to novel transducer technologies applied to complicated multifield vibration problems involving elastic, temperature, electric, magnetic, and light interactions.
Abstract: Smart materials are increasingly applied to not only traditional sensors but to actuators, precision systems, adaptive or smart structures, mechatronic systems, structronic systems, and so on. The objective of this paper is to introduce the shock and vibration community to novel transducer technologies applied to complicated multifield vibration problems involving elastic, temperature, electric, magnetic, and light interactions. The active materials include piezoelectrics, electro- and magnetostrictive materials, shape memory alloys, electro- and magnetorheological fluids, polyelectrolyte gels, superconductors, pyroelectrics, photostrictive materials, photoferroelectrics, and magnetooptical materials. This paper provides an overview of these popular active materials and their applications to transducers (sensors/actuators), devices, precision mechatronic systems, and structronic systems. Note that the emphasis is placed on their fundamental characteristics, histories, material varieties, patents, and engineering applications.

68 citations


Journal ArticleDOI
TL;DR: The structural similarities between these four superb actuator materials are remarkable, and provide a key to the development of future smart materials as mentioned in this paper, which can be used to tune the properties of these materials.
Abstract: One of the qualities that distinguishes living systems from inanimate matter is the ability to adapt to changes in the environment. Smart materials have the ability to perform both sensing and actuating functions and are, therefore, capable of imitating this rudimentary aspect of life. Four of the most widely used smart materials are piezoelectric Pb(Zr, Ti)O 3 , electrostrictive Pb(Mg, Nb)O 3 , magnetostrictive (Tb, Dy)Fe 2 and the shape-memory alloy NiTi. All four are ferroic with active domain walls and two phase transformations, which help to tune the properties of these actuator materials. Pb(Zr, Ti)O 3 is a ferroelectric ceramic which is cubic at high temperature and becomes ferroelectric on cooling through the Curie temperature. At room temperature, it is poised on a rhombohedral-tetragonal phase boundary which enhances the piezoelectric coefficients. Terfenol, (Tb, Dy)Fe 2 , is also cubic at high temperature and then becomes magnetic on cooling through its Curie temperature. At room temperature, it too is poised on a rhombohedral-tetragonal transition which enhances its magnetostriction coefficients. Pb(Mg, Nb)O 3 and nitinol (NiTi) are also cubic at high temperatures and on annealing transform to a partially ordered state. On further cooling, Pb(Mg, Nb)O 3 passes through a diffuse phase transformation at room temperature where it exhibits very large dielectric and electrostrictive coefficients. Just below room temperature, it transforms to a ferroelectric rhombohedral phase. The partially ordered shape-memory alloy NiTi undergoes an austenitic (cubic) to martensitic (monoclinic) phase change just above room temperature. It is easily deformed in the martensitic state but recovers its original shape when reheated to austenite. The structural similarities between these four superb actuator materials are remarkable, and provide a key to the development of future smart materials.

Journal ArticleDOI
TL;DR: The boundary element method is applied to problems of three-dimensional linear piezoelectricity as mentioned in this paper, where the continuum equations for conservation of linear momentum and charge are combined into one governing equation for piezoceramic material.
Abstract: The boundary element method is applied to problems of three-dimensional linear piezoelectricity. The continuum equations for conservation of linear momentum and charge are combined into one governing equation for piezoelectricity. A single boundary integral equation is developed from this combined e eld equation and Green’ s solution for a piezoelectric medium. Green’ s function and its derivatives are derived using the radon transform, and the resulting solution is represented by a line integral that is evaluated numerically using standard Gaussian quadrature. The boundary integral equation is discretized using eight-node isoparametric quadratic elements, resulting in a matrixsystem ofequations. Thesolution of theboundary problem forpiezoelectricmaterialsconsistsof elastic displacements, tractions, electric potentials, and normal charge e ux densities. The complete e eld solutions can be obtained once all boundary values have been determined. The accuracy of this linear piezoelectric boundary element method is illustrated with two numerical examples. The e rst involves a unit cube of material with an applied mechanical load. Thesecond exampleconsistsof a spherical holein an ine nitepiezoelectricbody loaded by a unit traction on itsboundary. Comparisonsare made to the analytical solution for the cube and an axisymmetric e nite element solution for the spherical hole. The boundary element method is shown to be an accurate solution procedure for general three-dimensional linear piezoelectric material problems. I. Introduction T HEbrothersPierreandJacquesCuriediscoveredpiezoelectricity in 1880 during their investigation of crystals. A coupling occurs between the electrical and mechanical e elds in these materials, such that application of an external mechanical loading induces achangeinpolarizationproportionaltoit.Conversely,applicationof an electric e eld produces a proportional material deformation. This phenomenon was discovered in ceramics in the 1940s, and the subsequent manufactured piezoceramic materialshave higher coupling properties than their naturally occurring predecessors. This strong piezoelectric effect has made these materials an important part of the emerging technologies of smart materials and structures. Smart structures are those that incorporate actuators and sensors that are integrated into the structure and have structural functionality. The sensors and actuators are used to ine uence the structure’ s states

Proceedings ArticleDOI
01 Mar 1998
TL;DR: An overview of the research being conducted within the Materials Division at NASA Langley Research Center on the development of smart material technologies for advanced airframe systems is presented in this paper, where a portion of the ongoing research in each of these areas of materials research is presented.
Abstract: Reported herein is an overview of the research being conducted within the Materials Division at NASA Langley Research Center on the development of smart material technologies for advanced airframe systems. The research is a part of the Aircraft Morphing Program which is a new six-year research program to develop smart components for self-adaptive airframe systems. The fundamental areas of materials research within the program are computational materials; advanced piezoelectric materials; advanced fiber optic sensing techniques; and fabrication of integrated composite structures. This paper presents a portion of the ongoing research in each of these areas of materials research.

Proceedings ArticleDOI
16 Jun 1998
TL;DR: In this paper, a smart material system is defined as a network of embedded electromechanical devices that are able to sense and affect their environment and autonomously adapt to changes in operating conditions.
Abstract: The results of an initial investigation in the use of smart material system for automobiles are presented. For this work, a smart material system is defined as a network of embedded electromechanical devices that are able to sense and affect their environment and autonomously adapt to changes in operating conditions. The development of smart material system for production vehicles has the potential for compact, lightweight subsystems that reduce vehicle weight and improve vehicle performance. This paper presents an overview of current technology and how it contrasts with the development of highly integrated smart material systems. Automotive design requirements are examined to highlight practical constraints associated with integrating smart material technology into automobiles. Representative examples of a embedded sensor-actuator system for camless engines and a smart automotive seat are presented to illustrate the design concepts.

Journal ArticleDOI
TL;DR: In this paper, a bibliographical review of the finite element methods (FEMs) applied to the analysis and simulation of smart materials and structures is presented, including smart materials, smart components/structures, smart sensors and actuators, controlled structures technology, and other topics.
Abstract: This paper gives a bibliographical review of the finite-element methods (FEMs) applied to the analysis and simulation of smart materials and structures. The bibliography at the end of the paper contains references to papers, conference proceedings and theses/dissertations on the subject that were published between 1986-1997. The following topics are included: smart materials; smart components/structures; smart sensors and actuators; controlled structures technology; and other topics.

Proceedings ArticleDOI
16 May 1998
TL;DR: This paper addresses the problem of reducing the hysteresis found in the actuation of most smart materials, and introduces the concept of phaser, an operator which shifts the phase of a periodic signal but keeps its magnitude unchanged.
Abstract: This paper addresses the problem of reducing the hysteresis found in the actuation of most smart materials. They are divided in two groups: systems with no saturation (e.g. piezoelectric actuators), and systems with saturation (e.g. shape memory actuators). For the control of the first group the concept of phaser is introduced, an operator which shifts the phase of a periodic signal but keeps its magnitude unchanged. Since it is possible to approximate phasers with linear filters, it is possible to design practical compensators. The design of a phaser requires the knowledge of one parameter /spl phi/, easily identified from experimental transfer function estimates. For the second group, two phasers are used in a tandem connection. One phaser is designed as described before, and the second is designed so as to vary with the input. This compensation reduces the hysteresis to a single saturation. To show its effectiveness, simulation results are provided using the hystery model, then the method is applied to an SMA actuator.

Journal ArticleDOI
TL;DR: In this article, the concept of recoverable plastic deformation opens the way to the application of smart materials and, in particular, of shape memory alloys (SMAs), and the characterization of the Ti Ni alloy structural component is discussed.
Abstract: A way of reasoning to reduce the response of a structural system under dynamic excitation is to think in terms of energy dissipation via plastic deformation devices. The concept of recoverable plastic deformation opens the way to the application of smart materials and, in particular, of shape memory alloys (SMAs). The characterization of the Ti Ni alloy structural component, with a complete definition of its mechanical properties and assembling features, is discussed.

Journal ArticleDOI
TL;DR: In this article, three dynamic models of a smart materials robot are presented and compared by numerical simulations in both time and frequency domains to verify the correctness of the models and to analyze the performance of the system.
Abstract: Three dynamic models of a smart materials robot are presented First, Hamilton's approach is adopted to derive an accurate model expressed in partial differential equations, which is too complicated to be applicable in engineering practice Based on the partial differential equations model, the assumed modes method and the finite element method are employed to derive two finite dimensional models in the forms of ordinary differential equations, which are readily usable for controller design All of the models show that the model of a smart materials robot cannot be simply taken to be the same as that of a pure flexible robot, and the parameters of the smart materials robot should be properly chosen to avoid the divergent open-loop responses For completeness, both mechanical dynamics and electrical dynamics are explicitly included in all of these models, although it is shown analytically and numerically that the latter dynamics can be omitted in engineering applications Comparative studies between the assumed modes method model and the finite element method model are carried out by numerical simulations in both time and frequency domains to verify the correctness of the models and to analyze the performance of the system

Journal ArticleDOI
TL;DR: In this paper, a two-phase potential method is introduced to linear piezoelectricity and worked out for the case of the antiplane deformation of a smart composite.
Abstract: The piezoelectric smart composite material consisting of two discrete phases of hexagonal piezoelectric crystals is subjected to mechanical and electric loads causing out-of-plane displacement and in-plane electric field. The two-phase potential method is introduced to linear piezoelectricity and worked out for the case of the antiplane deformation of a piezoelectric composite. It is shown that only two holomorphic functions (two-phase potentials) are sufficient to fully describe the field variables of the corresponding piezoelectric problem. The power of the method is exhibited by finding the two-phase potential solution to several piezoelectric problems of micromechanics of smart composites.

Journal ArticleDOI
01 Jan 1998-Nature
TL;DR: In this paper, a new addition to their number is the switchable window, a sandwich of glass, thin metal-hydride films and some medium for delivering hydrogen gas, which can be reversibly converted from reflecting to transparent states.
Abstract: Smart materials, which can change their physical properties, enable a building to adjust its environment to the prevailing conditions. A new addition to their number is the switchable window -- a sandwich of glass, thin metal-hydride films and some medium for delivering hydrogen gas, which can be reversibly converted from reflecting to transparent states. When the technology has improved to allow electronic switching, instead of requiring direct pumping of gas, such switchable windows might be used in energy-conscious building design -- and for the lazy, they would make a good alternative to curtains.

Proceedings ArticleDOI
21 Jul 1998
TL;DR: In this paper, sensory mechanisms in smart material systems, methods for the instrumentation of integrated smart structural systems, and techniques for the characterization of smart or designed materials that are substantially different from methods used to characterize more conventional materials are discussed.
Abstract: This conference focuses on sensory mechanisms in smart material systems, methods for the instrumentation of integrated smart structural systems, and techniques for the characterization of smart or designed materials that are substantially different from methods used to characterize more conventional materials. In this paper, an overview of the purpose of the conference will be provided describing its place within smart structures research, the conference structure will be discussed, and some of the conference papers of note will be previewed.

Journal ArticleDOI
Tohru Shiga1
01 Jan 1998
TL;DR: In this article, the authors review the current status of our knowledge of electromechanical effects that take place in smart polymer gels and present applications of these effects in electric fields.
Abstract: “Smart” polymer gels actively change their size, structure, or viscoelastic properties in response to external signals The stimuli-responsive properties, indicating a kind of intelligence, offer the possibility of new gel-based technology The article attempts to review the current status of our knowledge of electromechanical effects that take place in smart polymer gels Deformation and the mechanism of polyelectrolyte gel behavior in electric fields are first studied experimentally and then theoretically In particular, the swelling or bending is discussed in detail Particulate composite gels whose modulus of elasticity can vary in electric fields are revealed as a new smart material The driving force causing varying elastic modulus in electric fields is explained by a qualitative model based upon polarized particles Finally, applications of the two electromechanical effects are presented

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional model for in-plane vibrations of a cantilever plate with a non-symmetrical damage is used in the context of defect identification in materials with piezoelectric ceramic patches bonded to their surface.
Abstract: A two-dimensional model for in-plane vibrations of a cantilever plate with a non-symmetrical damage is used in the context of defect identification in materials with piezoelectric ceramic patches bonded to their surface. These patches can act both as actuators and sensors in a self-analyzing fashion, which is a characteristic of smart materials. A Galerkin method is used to approximate the dynamic response of these structures. The natural frequency shifts due to the damage are estimated numerically and compared to experimental data obtained from tests on cantilever aluminum plate-like structures damaged at different locations with defects of different depths. The damage location and extent are determined by an enhanced least square identification method. Efficacy of the frequency shift based algorithms is demonstrated using experimental data.

Patent
11 Sep 1998
TL;DR: In this paper, a smart material control system and related method is disclosed for adaptively controlling the movement of an adaptive structure, which includes two smart material layers bonded to a conductive substrate in a bimorph configuration.
Abstract: A smart material control system and related method is disclosed for adaptively controlling the movement of an adaptive structure. The adaptive structure includes a smart material layer bonded to a conductive substrate in a bimorph configuration. A charge projector, such as an electron gun, is utilized to project charges onto the smart material layer of the adaptive structure. A voltage/charge source adaptively controls the potential of the conductive substrate. Depending on the placement of the projected charges and the adaptively controlled potential of the conductive substrate the displacement/curvature is precisely controlled. In an alternate embodiment, two smart material layers are bonded together to form an adaptive structure controlled independently in the x- and y- directions. Also, an array of charge projectors and/or conductive substrate sections may be used to provide varying and broad control of adaptive structures.

01 Jul 1998
TL;DR: In this paper, the authors discuss issues related to modeling of nonlinearities and hysteresis arising in a class of magnetorheological-based smart elastomers.
Abstract: : We discuss issues related to modeling of nonlinearities and hysteresis arising in a class of magnetorheological-based smart elastomers. The dynamic models intended for use in parameter estimation and control problems are presented in the context of simple elongation of a filled rubber-line rod. Theoretical computational and experimental results are given.

Proceedings ArticleDOI
16 Dec 1998
TL;DR: In this paper, the motion control problem for MEMS was solved by using nonlinear dynamics of MEM structures (smart materials) and driving circuitry. Analytical, numerical and experimental results are presented.
Abstract: Monolithic micro-electromechanical system (MEMS) technology allows one to fabricate and integrate MEM structures (micro-actuators and microsensors) with driving, controlling, and signal processing circuitry needed to attain data analysis, and control. This monolithic improves the performance of MEMS, reduces the cost and packaging, increases efficiency and reliability. The application of MEMS attains the major breakthrough in actuators, motion devices and servo-systems. The current trends in development and deployment of MEMS have facilitated the unified activities in the fabrication and analysis of smart structures and materials, design of micro-circuitry and controllers. In this paper, we solve the motion control problem for MEMS by using nonlinear dynamics of MEM structures (smart materials) and driving circuitry. Analytical, numerical and experimental results are presented.

01 Jan 1998
TL;DR: In this article, the results of experimental and theoretical investigations of the induced strain transfer from a piezoceramic material to the metal sub-structure through a bonding layer were presented.
Abstract: Smart material actuator systems are being increasingly used in active vibration control, micro-motion as well as macro-motion applications. Viability of such macro-motion system depends upon how the induced strain in the smart material is transferred to the metal sub-structure. This paper presents results of experimental and theoretical investigations of the induced strain transfer from a piezoceramic material to the metal sub-structure through a bonding layer. The factors selected for the analysis in obtaining optimum strain transfer include the type of the sub-structure material, type of bonding material, thickness of bonding layer, and the thickness of the piezoceramic material. Taguchi method is used to experimentally investigate the individual effects of all these factors. A finite difference based numerical scheme has been developed to study such configurations. Results indicate that the finite difference and analytical methods agree well in determining the effect of parameters on induced strain transfer. Both experimental and theoretical results agree well within the scope of the Taguchi study in determining the effect of parameters. Results show that the type of substructure material and the thickness of piezoceramic play important roles in determining the effectiveness of strain transfer.

Proceedings ArticleDOI
16 Apr 1998
TL;DR: In this article, the authors present a review of the state-of-the-art of smart actuators and sensors and integrated systems and point out the needs for future research.
Abstract: A smart structure involves distributed actuators and sensors, and one or more microprocessors that analyze the responses from the sensors and use distributed-parameter control theory to command the actuators to apply localized strains to minimize system response. A smart structure has the capability to respond to a changing external environment (such as loads or shape change) as well as to a changing internal environment ( such as damage or failure). It incorporates smart actuators that allow the alteration of system characteristics ( such as stiffness or damping) as well as of system response (such as strain or shape) in a controlled manner. Many types of actuators and sensors are being considered, such as piezoelectric materials, shape memory alloys, electrostrictive materials, magnetostrictive materials, electro-rheological fluids and fiber optics. These can be integrated with main load-carrying structures by surface bonding or embedding without causing any significant changes in the mass or structural stiffness of the system. Numerous applications of smart structures technology to various physical systems are evolving to actively control vibration, noise, aeroelastic stability, damping, shape and stress distribution. Applications range from space systems, fixed-wing and rotary-wing aircraft, automotive, civil structures and machine tools. Much of the early development of smart structures methodology was driven by space applications such as vibration and shape control of large flexible space structures, but now wider applications are envisaged for aeronautical and other systems. Embedded or surface-bonded smart actuators cn an airplane wing or helicopter blade will induce alteration of twist/camber of airfoil (shape change), that in turn will cause variation of lift distribution and may help to control static and dynamic aeroelastic problems. Applications of smart structures technology to aerospace and other systems are expanding rapidly. Major barriers are: actuator stroke, reliable data base of smart material characterteristics, non-availability of robust distributed parameter control stratgies, and non-existent mathematical modeling of smart systems. The objective of this paper is to review the state-of-the-art of smart actuators and sensors and integrated systems and point out the needs for future research.

Dissertation
29 Jul 1998
TL;DR: This thesis presents the design and development of two switching amplifiers used to drive the so-called smart material actuators, and peak current mode control is proposed to reduce the actuator’s hysteretic behavior.
Abstract: This thesis presents the design and development of two switching amplifiers used to drive the so-called smart material actuators. Different from conventional circuits, a smart material actuator is ordinarily a highly capacitive load. Its capacitance is non-linear and its strain is hysteretic with respect to its electrical control signal. This actuator’s reactive load property usually causes a large portion of reactive power circulating between the power amplifier and the driven actuator, thus reduces the circuit efficiency in a linear power amplifier scenario. In this thesis, a switching amplifier design based on the PWM technique is proposed to develop a highly efficient power amplifier, and peak current mode control is proposed to reduce the actuator’s hysteretic behavior. Since the low frequency current loop gain tends to be low due to the circuit’s capacitive load, average current mode control is further proposed to boost the low frequency current loop gain and improve the amplifier’s low frequency performance. Both of the circuits have been verified by prototype design and their experimental measurement results are given.

Proceedings ArticleDOI
21 Jun 1998
TL;DR: In this paper, a controller design for a single-link smart material robot, which combines both the advantages of flexible robots and piezoelectric materials, is investigated, where the controllers are derived from the basic energy-work relationship, which is independent of the system dynamics.
Abstract: In this paper, the controller design is investigated for a single-link smart material robot, which combines both the advantages of flexible robots and piezoelectric materials. To avoid any drawbacks resulting from model uncertainties and/or model truncations, a class of model-free controllers are proposed for the smart material robot system to achieve both tip regulation and residual vibration suppression. In contrast to traditional model-based methods, the controllers presented are derived from the basic energy-work relationship, which is independent of the system dynamics. Furthermore, the controllers are easily implementable because all the signals can be chosen readily measurable. Simulations are carried out to show the effectiveness of the presented approach.