Showing papers on "Smart material published in 2003"
TL;DR: The application of smart materials as tools to solve biological problems such as bioseparation, drug delivery, biosensor design, tissue engineering, protein folding, and microfluidics are discussed.
336 citations
TL;DR: In this paper, the authors present a review of recent work in the area of smart materials and structures and apply formal optimization methods to the design of smart structures and actuators, as well as optimization strategies for topology design of actuators.
Abstract: Much of the recent and past work in the area of smart materials and structures has focused on analysis of actuators and actively controlled systems. Although many sophisticated analysis models have been developed, they are often coupled with ad hoc design methods or informal optimization procedures. A subset of the work done by the smart structures community has focused on development of formal design methodologies and optimization methods specifically for smart actuators and structures. The objective of this paper is to review the current work in development of design methodologies and application of formal optimization methods to the design of smart structures and actuators. In a related paper, optimization strategies for sensor and actuator placement were reviewed by a researcher at NASA Langley in 1999. The current paper reviews the recent work done in this area since 1999, in addition to optimization strategies for topology design of actuators, actively controlled structures, and drive electronics de...
312 citations
TL;DR: In this article, the deformation of magneto-sensitive (MS) elastic solids with particular reference to elastomers whose mechanical properties may be changed rapidly by the application of a magnetic field is discussed.
Abstract: In this paper we first summarize the equations governing the deformation of magneto-sensitive (MS) elastic solids with particular reference to elastomers whose mechanical properties may be changed rapidly by the application of a magnetic field. These 'smart materials' typically consist of micron-sized ferrous particles dispersed within an elastomeric matrix. Constitutive relations for isotropic MS-elastic solids are examined. The equations are then applied to a representative geometry appropriate for applications, that in which the material is confined to a circular cylindrical tube in the presence of a radial magnetic field. The material is then subject to an axial shear deformation. Results are illustrated for two specific material models, for each of which the shear stiffness of the material increases with the magnetic field strength, as observed in experiments on MS elastomers.
244 citations
TL;DR: In this paper, the full system of equations for deformable magneto-sensitive elastomers in an electro-magnetic field is considered and a simple phenomenological model is suggested.
158 citations
TL;DR: A neutron diffraction investigation of the development of intergranular stresses, which vary as a function of grain orientations, in 316 stainless steel during high-cycle fatigue found that a large inter granular stress developed before cracks started to appear.
Abstract: There have been numerous efforts to understand and control the resistance of materials to fracture by repeated or cyclic stresses. The micromechanical behaviours, particularly the distributions of stresses on the scale of grain size during or after mechanical or electrical fatigue, are crucial to a full understanding of the damage mechanisms in these materials. Whether a large microstress develops during cyclic deformation with a small amount of monotonic strain but a large amount of accumulated strain remains an open question. Here, we report a neutron diffraction investigation of the development of intergranular stresses, which vary as a function of grain orientations, in 316 stainless steel during high-cycle fatigue. We found that a large intergranular stress developed before cracks started to appear. With further increase of fatigue cycles, the intergranular stress decreased, while the elastic intragranular stored energy continued to grow. One implication of our findings is that the ratio between the intergranular and intragranular stored energies during various stages of fatigue deformation may validate the damage mechanism and can be used as a fingerprint for monitoring the state of fatigue damage in materials.
91 citations
TL;DR: In this article, a bibliographical review of the finite element methods (FEMs) applied to the analysis and simulation of smart materials and structures is given, including smart materials, smart components/structures, smart sensors and actuators, and controlled structures technology.
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 is an addendum to the Smart materials and structures—a finite-element approach: a bibliography (1986–1997) published in 1998 Modelling Simul. Mater. Sci. Eng. 6 293–334. The added bibliography at the end of this article contains 977 references to papers and conference proceedings on the subject that were published in 1997–2002. The following topics are included: smart materials, smart components/structures, smart sensors and actuators, and controlled structures technology.
70 citations
TL;DR: The magnetic polymer gel as discussed by the authors represents a new type of composites consisting of small magnetic particles, usually from the nanometer range to the micron range, dispersed in a highly elastic polymeric gel matrix.
Abstract: The combination of polymers with nanomaterials displays novel and often enhanced properties compared to the traditional materials. They can open up possibilities for new technological applications. The magnetic polymer gel represents a new type of composites consisting of small magnetic particles, usually from the nanometer range to the micron range, dispersed in a highly elastic polymeric gel matrix. Combination of magnetic and elastic properties leads to a number of striking phenomena that are exhibited in response to impressed magnetic fields. Giant deformational effects, high elasticity, anisotropic properties, temporary reinforcement and quick response to magnetic field open new opportunities for using such materials for various applications.
54 citations
TL;DR: In this article, an experimental investigation of the behavior of a sandwich beam with Electro-Rheological (ER) fluid acting as the core material is performed and significant improvements in damping properties are achieved in experiments and the damping contributions by viscous and non-viscous forces are estimated by force state mapping (FSM) technique.
44 citations
TL;DR: This paper addresses the value inversion problem for a class of discretized Preisach operators, i.e., to find an optimal input trajectory given a desired output value, and develops a state-space reduction scheme for the FSM, which significantly saves the memory and the computation time.
39 citations
TL;DR: In this paper, an experimental investigation of the behavior of a sandwich beam with Electro-Rheological (ER) fluid acting as the core material is performed and significant improvements in damping properties are achieved in experiments and the damping contributions by viscous and non-viscous forces are estimated by force state mapping (FSM) technique.
37 citations
14 Oct 2003
TL;DR: In this paper, the effect of the bond layer on the electro-mechanical response of a smart system is studied, and the effects of shear lag due to the finite thickness bond layer were successfully identified.
Abstract: The electro-mechanical (EM) impedance method is gradually emerging as a widely accepted technique for structural health monitoring and systems identification. The method utilizes smart piezoceramic (PZT) transducers intimately bonded to the surface of a structural substrate. Through the unique electro-mechanical properties of the PZT transducers, the presence of damage, as well as the dynamical properties of the host structure are captured and reflected in the electrical admittance response. In the present work, the effect of the bond layer on the electro-mechanical response of a smart system is being studied. Experiments with the EM impedance method were performed on laboratory-sized beams. Consequently, the effects of shear lag due to the finite thickness bond layer were successfully identified. This was followed by the theoretical analysis of shear lag effects. It was found that the induced strain behavior of the structural specimen in question is inevitably modified by the presence of shear lag between the PZT transducer and the structural substrate. Subsequently, the EM admittance response of the beam specimens were simulated based on the results gathered from the theoretical analysis. Incidentally, it was found that the theoretical model clearly depicts the trends of the measured response.
12 Mar 2003
TL;DR: In this paper, the atomistic nature of shape memory and superelasticity of Nitinol and the associated unique changes in mechanical properties are described, which is exemplified by its use for self-expanding stents.
Abstract: The paper presents Nitinol, a Nickel-Titanium shape memory alloy, as a smart material for medical implants and devices. The atomistic nature of shape memory and superelasticity of Nitinol and the associated unique changes in mechanical properties are described. The smartness of the material is exemplified by its use for self-expanding stents. Caused by the stress hysteresis of superelastic Nitinol, these devices exhibit a biased stiffness behavior, i.e. they exert a low chronic outward force on the vessel wall, but resist external deformation with much higher forces. Some recent developments of thin film Nitinol stents and filters are also discussed.
TL;DR: In this paper, high-resolution non-destructive imaging methods including microfocus x-rays, ultrasonics and eddy currents are used to characterize damage resulting from non-optimal manufacturing and external load.
Abstract: Smart materials based on carbon-fibre-reinforced plastic (CFRP) with embedded PZT sensors and actuators are expected to be a favourite composite for vibration damping and noise reduction. Due to the wide variety of physical properties of the components, various damage mechanisms may reduce or even remove the sensing and actuating capabilities of the piezoceramic material. Comprehensive non-destructive characterization and integral health monitoring help to optimize the structure and its manufacturing and are essential prerequisites to ensure performance and availability of smart components during their lifetime. The first part of the paper presents high-resolution non-destructive imaging methods including microfocus x-rays, ultrasonics and eddy currents. These methods are used to characterize damage resulting from non-optimal manufacturing and external load. The second part is dedicated to newly developed imaging techniques using the active piezoceramics as transmitters of acoustic, electromagnetic and thermal fields. The third part focuses on health monitoring by impedance spectroscopy using the same piezoceramics as for vibration damping. Electromechanical finite-element modelling and experimental investigations of strip-shaped specimens have shown the close connection between mechanical properties and electrical impedance.
TL;DR: In this article, an analytical model for composite laminated plates of general layup with either isotropic or anisotropic active layers is derived using the variational principle of virtual work along with the classical plate and lamination theories.
Abstract: The objective of this paper is to examine the feasibility of using monolithic, directed, or fibrous piezoelectric smart materials to control the shape of a subsonic projectile fin during flight. To achieve this goal, an analytical model for composite laminated plates of general layup with either isotropic or anisotropic active layers is derived. The mathematical formulation uses the variational principle of virtual work along with the classical plate and lamination theories and the anisotropic piezoelectric constitutive equations. A solution procedure that adopts the concepts of the extended Kantorovich method and imposes them on the variational ("weak") form of the active plate problem is derived. The results of the proposed model are compared with those of other classical approximated solutions, as well as results of finite element analysis. Finally, the derived model is used for the quantitative examination of four basic design concepts for twist actuation and shape control of the investigated fin. The...
Patent•
03 Jul 2003
TL;DR: In this paper, the authors propose a method for dimensioning and placemat of a compensating insert with respect to the support structure to obtain an accurate and cost effective insert.
Abstract: An apparatus having a smart material actuator (32), a support structure (12) and at least one temperature compensating material insert (38), either externally mounted to the support structure, integrally formed with the support structure, or any combination thereof. The apparatus includes a mechanically leveraged electrically stimulated smart material, such as piezoelectric material. The support structure and actuator are susceptible to the effects of differences in thermal coefficients of expansion of the materials used in the construction. The smart material typically displaces less than 0.001 inches and is leveraged up to fifty times to obtain useful movement. The temperature effect on the smart material is therefore leveraged and amplified producing undesirable motion in the apparatus with ambient and/or operating temperature changes. A method for dimensioning and placemat of a compensating insert with respect to the support structure provides an accurate and cost effective compensating insert.
12 Aug 2003
TL;DR: In this article, a power-by-wire actuator is proposed for UAVs. The actuators under development combine a high energy density smart material, specifically a piezoelectric material, with internal servohydraulic components, for a net high energy output.
Abstract: The application of a new class of actuators is considered. The actuators under development combine a high energy density smart material, specifically a piezoelectric material, with internal servohydraulic components. Large displacement outputs are produced, while the high force capacity of the stiff smart material is retained, for a net high-energy output. The actuator is considered “power-by-wire” because only electrical power is provided from the vehicle or system controller. A primary motivating application is in unmanned combat air vehicles (UCAVs). The particular actuation needs of these vehicles, in flight control and other utility functions, are described and distilled to a set of relevant device requirements. Other potential applications, such as flight motion simulation, are also highlighted. The new actuation architecture offers specific advantages over centralized hydraulic systems and has capabilities not present in electromechanical actuators (EMAs). The main advantage over centralized hydraulic systems is the elimination of the need for hydraulic lines. Compared to motor-driven ball screw type EMAs, the new actuators offer higher frequency response, and a larger peak-to-average output. A laboratory test facility designed to represent the loading experienced by a UCAV control surface is described. Key steps necessary to flight qualify the actuator are introduced.
TL;DR: An experimental study of a smart-materials actuator driven by a microwave is presented in this article, where a proof-of-concept experiment using a smart material, such as thin layer composite unimorph ferroelectric driver and sensor (THUNDER), has been demonstrated with wirelessly transmitted microwave power.
Abstract: An experimental study of a smart-materials actuator driven by a microwave is presented in this paper. A proof-of-concept experiment using a smart material, such as thin layer composite unimorph ferroelectric driver and sensor (THUNDER), has been demonstrated with wirelessly transmitted microwave power. Such an advance system will offer a new class of smart devices that are remotely controlled via wirelessly transmitted power. Thus, a system of this nature autonomously functions without an onboard power infrastructure. Potential applications are integrated sensors, actuators, and smart flight control in space applications, as well as biologically-inspired systems. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 331–333, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10757
01 Aug 2003
TL;DR: In this article, the robust control of a smart structure with disturbances due to inherent hysteresis and sensor noise is considered, where the authors demonstrate the techniques on a magnetostrictive transducers.
Abstract: Applications utilizing smart materials are rapidly increasing and include high speed milling and hybrid motor design. Such application utilize magnetostrictive transducers operating in hysteretic and nonlinear regimes. To achieve the high performance capabilities of these transducers, models and control laws must accommodate the nonlinear dynamics in a manner which is robust and facilitates real-time implementation. To this end, the models and control algorithms must utilize known physics to the highest degree possible, be low order, and be sufficiently robust to operate under realistic conditions. In this paper we consider the robust control of a smart structure with disturbances due to inherent hysteresis and sensor noise. We dmeonstrate the techniques on a magnetostrictive transducers but they are sufficiently general to be utilized on several commonly used smart materials. The performance of the control strategies are illustrated through numerical examples.
12 Aug 2003
TL;DR: In this paper, the authors describe design methodologies for construction of an actuator that uses smart materials to provide hydraulic fluid power, and test results quantifying pump pressure and flow, and actuator force and velocity are summarized.
Abstract: This paper describes design methodologies for construction of an actuator that uses smart materials to provide hydraulic fluid power. In the class of actuators described, hydraulic fluid decouples the operating frequency of the output cylinder from the drive frequency of the piezoelectric or other smart material. This decoupling allows the piezoelectric to be driven at high frequency, to extract the maximum amount of energy from the material, and the hydraulic cylinder to be driven at low frequencies to provide long stroke. However, due to fluid compressibility and structural compliance, the fundamental impedance match between the fluid and the piezoelectric make it difficult to convert energy from the piezoelectric into pressurized hydraulic fluid flow. The basic design tradeoffs and major technical issues are discussed in the areas of materials, mechanical design, and fluid-mechanical interface. Prototype devices and component measurements are presented. Test methods are described, and test results quantifying pump pressure and flow, and actuator force and velocity are summarized. The series of tests show the potential of these devices for high force long stroke devices powered by smart materials.
14 Oct 2003
TL;DR: In this paper, the authors present a review of MEMS and NEMS based smart systems for various applications mentioned above, such as scanning probe microscopy, field emission devices, nanoelectronics, H2-storage, electromagnetic absorbers, ESD, EMI films and coatings and structural composites.
Abstract: The microelectronics industry has seen explosive growth during the last thirty years. Extremely large markets for logic and memory devices have driven the development of new materials, and technologies for the fabrication of even more complex devices with features sizes now down at the sub micron and nanometer level. Recent interest has arisen in employing these materials, tools and technologies for the fabrication of miniature sensors and actuators and their integration with electronic circuits to produce smart devices and systems. This effort offers the promise of: (1) increasing the performance and manufacturability of both sensors and actuators by exploiting new batch fabrication processes developed including micro stereo lithographic and micro molding techniques; (2) developing novel classes of materials and mechanical structures not possible previously, such as diamond like carbon, silicon carbide and carbon nanotubes, micro-turbines and micro-engines; (3) development of technologies for the system level and wafer level integration of micro components at the nanometer precision, such as self-assembly techniques and robotic manipulation; (4) development of control and communication systems for MEMS devices, such as optical and RF wireless, and power delivery systems, etc. A novel composite structure can be tailored by functionalizing carbon nano tubes and chemically bonding them with the polymer matrix e.g. block or graft copolymer, or even cross-linked copolymer, to impart exceptional structural, electronic and surface properties. Bio- and Mechanical-MEMS devices derived from this hybrid composite provide a new avenue for future smart systems. The integration of NEMS (NanoElectroMechanical Systems), MEMS, IDTs (Interdigital Transducers) and required microelectronics and conformal antenna in the multifunctional smart materials and composites results in a smart system suitable for sending and control of a variety functions in automobile, aerospace, marine and civil strutures and food and medical industries. This unique combination of technologies also results in novel conformal sensors that can be remotely sensed by an antenna system with the advantage of no power requirements at the sensor site. This paper provides a brief review of MEMS and NEMS based smart systems for various applications mentioned above. Carbon Nano Tubes (CNT) with their unique structure, have already proven to be valuable in their application as tips for scanning probe microscopy, field emission devices, nanoelectronics, H2-storage, electromagnetic absorbers, ESD, EMI films and coatings and structural composites. For many of these applications, highly purified and functionalized CNT which are compatible with many host polymers are needed. A novel microwave CVD processing technique to meet these requirements has been developed at Penn State Center for the Engineering of Electronic and Acoustic Materials and Devices (CEEAMD). This method enables the production of highly purified carbon nano tubes with variable size (from 5 - 40 nm) at low cost (per gram) and high yield. Whereas, carbon nano tubes synthesized using the laser ablation or arc discharge evaporation method always include impurity due to catalyst or catalyst support. The Penn State research is based on the use of zeolites over other metal/metal oxides in the microwave field for a high production and uniformity of the product. An extended coventional purification method has been employed to purify our products in order to remove left over impurity. A novel composite structure can be tailored by functionalizing carbon nano tubes and chemically bonding them with the polymer matrix e.g. block or graft copolymer, or even cross-linked copolymer, to impart exceptional structural, electronic and surface properties. Bio- and Mechanical-MEMS devices derived from this hybrid composites will be presented.
TL;DR: In this paper, the impedance-based non-destructive testing technique can be used to identify damage in laminated composites at low temperature, but regular piezoceramic patches have been found to be unsuitable for damage detection at cryogenic temperatures.
Abstract: Through a series of experiments presented in this paper, the impedance-based non-destructive testing technique can be used to identify damage in laminated composites at low temperature. However, regular piezoceramic patches have been found to be unsuitable for damage detection at cryogenic temperatures. For impedance-based nondestructive testing on composite laminates at true cryogenic environments, the results presented in this paper suggest that an alternative type of actuator based on smart materials should be sought. The piezoceramic transducer for cryogenic environments should be able to produce good impedance measurements at cryogenic temperatures without much noise. The authors are conducting an on-going research program to identify such a material.
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TL;DR: In this article, the optimal number of smart dust particles for generating precise, computationally feasible and cost effective 3D weather maps was investigated and an optimal matching algorithm for the generalized scenario, when there are N Smart Dust particles and M ground receivers.
Abstract: Smart Dust particles, are small smart materials used for generating weather maps. We investigate question of the optimal number of Smart Dust particles necessary for generating precise, computationally feasible and cost effective 3-D weather maps. We also give an optimal matching algorithm for the generalized scenario, when there are N Smart Dust particles and M ground receivers.
TL;DR: Fibers and coatings with unique optical, magnetic, and electrical properties are being widely studied for use in both military and commercial applications as mentioned in this paper, with unique tunable coloration properties across the visible spectrum as well as spanning the infrared and ultraviolet region of the electromagnetic spectrum.
Abstract: Fibers and coatings with unique optical, magnetic, and electrical properties are being widely studied for use in both military and commercial applications. New materials are being developed in this research effort, with unique tunable coloration properties across the visible spectrum as well as spanning the infrared and ultraviolet region of the electromagnetic spectrum. These dynamic color-responsive “chameleon” fiber systems will have wide application to a variety of new textile products. These new materials will also allow penetration into markets normally not dependent on textile materials. New markets, such as the optical communication and electronics market areas, will include bio-sensors, detector applications for textile materials, and “smart materials” that can change their color, hue, or depth of shade by application of a static or dynamic electric field for applications such as smart uniforms.
TL;DR: In this paper, the feasibility of using electroactive hydrogels as materials in a changeable focal length lens (Smart Lens) is investigated, where the authors focus on identifying and controlling the parameters, such as crosslink density and degree of neutralization, that affect the required gel properties.
01 Oct 2003
TL;DR: In this paper, the authors investigated the application of smart materials in civil engineering by focusing on the literature review, basic information collection, and basic mechanic properties of smart material, including shape memory and superelasticity.
Abstract: With the development of materials and technology, many new materials find their applications in civil engineering to deal with the deteriorating infrastructure. Smart material is a promising example that deserves a wide focus, from research to application. With two crystal structures called Austenite and Martensite under different temperatures, smart material exhibits two special properties different from ordinary steels. One is shape memory, and the other is superelasticity. Both of these two properties can suit varied applications in civil engineering, such as prestress bars, self-rehabilitation, and two-way actuators, etc. One of the main objectives of the research is to investigate the application of smart materials in civil engineering by focusing on the literature review, basic information collection, and basic mechanic properties of smart materials. In axial tension tests, the force-extension curve and stress-strain curve of shape memory and superelasticity materials were measured separately. These curves verify the research of forerunners. Four beam experiments were conducted to evaluate the performance of flexure beams with superelasticity material as reinforcement bars. Load-displacement relationship at the midspan, strains on the surface of the concrete beam, and cracking width for different loads were measured. This research is just the first step in the investigation of the application of smart materials in structural engineering. Some bigger beams are prepared for experiments in the near future.
18 Aug 2003
TL;DR: In this article, the authors used the Brillouin scattering in singlemode optical fibers to evaluate the influence of different fiber coatings and embedding techniques on the performance of composite materials.
Abstract: Composite materials based on glass, carbon and aramid fibers have many advantages such as fast application, lightweight and corrosion resistance, and are widely diffused for manufacturing of tanks, pipings and for restoration, upgrade and seismic retrofit of structures and historical heritage. As several questions regarding long term durability of composite strengthenings remains still unsolved, monitoring of strain and temperature is strongly recommended, respectively to assess proper load transfer and no glass phase transition of the polymeric matrix. In this research work strain and temperature distributed sensing trough Brillouin scattering in single-mode optical fibers was used in different tests in order to understand the influence of different fiber coatings and embedding techniques. Pressure tests were performed on a GFRP piping with inhomogeneous strengthening layout and Brillouin strain data were compared with conventional strain gages. A smart CFRP material has been also developed and evaluated in a seismic retrofit application on an historical building dated 1500 that was seriously damaged in the earthquake of 1997. The developed embedding technique has been demonstrated successful to obtain fiber-optic smart composites with low optical losses, and the data comparison between Brillouin and resistive strain gauges confirms Brillouin technique is very effective for composite monitoring.
TL;DR: In this article, a smart mild steel damper is proposed to provide active damping for seismic control of structures, which is bonded to the surface of hysteric dampers, and is employed as actuator to exert active control force to increase damping effect for the vibration reduction of structural systems.
TL;DR: In this article, the influence of conditions of magnetoelastics synthesis (with or without magnetic field) on change of their shape in a magnetic field is under consideration, and it is revealed that the formation of chains of magnetic particles in the magnetic field during samples synthesis results in anisotropy of magnetic and elastic properties.
Patent•
30 Jul 2003
TL;DR: In this paper, a DC-to-DC converter with a proportional, mechanically-leveraged actuator is proposed to stimulate an electrically-stimulated smart material.
Abstract: An apparatus using electrically-stimulated smart material requires a power source to stimulate the material. This power source has three main functions, (1) to apply a known voltage potential across the smart material, (2) to convert from the control voltage to a level suitable for the smart material, and (3) to regulate the voltage based on a control input. The power source is a DC to DC converter with special properties achieved by supplying a variable stimulating voltage or actively discharging the actuator. The circuit also provides a dead band, or hysteresis, between the charge point and discharge point. When this circuit is applied with a proportional, mechanically-leveraged smart material actuator, a general-purpose industrial actuator becomes a cost-effective solution.