bluuebunny/crossref_metadata_2025 huggingface dataset:
Pb(Zr,Ti)O3 [PZT] Fibers-Fabrication and Measurement Methods
Authors: Yoshikawa Shoko , Selvaraj Ulagaraj , Moses Paul , Withams John , Meyer Richard , Shrout Thomas
Published: August 2009

Fine scale lead zirconate titanate (PZT) and niobium substituted PZT (Nb-PZT) piezoelectric fibers were fabricated from sol-gel processed viscous "sol" using the "spinning" meth-odology developed for the continuous production of glass fibers. Subsequent drying and firing at above 750'C gave pure perovskite PZT and Nb-PZT fibers of 30 am in average diameter. Further densification and grain growth were evident for fibers fired at 1250'C. Experimental methods for the determination of dielectric and polarization properties were developed to overcome inherent electric field difficulty relevant to fine scale fibers. The method to polarize fibers in a continuous manner was also demonstrated using 120 pm diameter extruded PZT fiber. The dielectric constant and polarization hysteresis values of the sol-gel derived fine fibers were comparable with that of bulk ceramics. Preliminary single fiber mechanical pull tests indicated that the tensile strength of 30 pm diameter PZT fibers were similar to that of bulk ceramics, being in the range of 35-55 MPa.
Tunable Electric Field Processing of Composite Materials
Authors: Bowen Christopher P. , Shrout Thomas R. , Newnham Robert E. , Randall Clive A.
Published: August 2009

Using the dielectrophoretic effect, it is possible to fabricate polymer/ceramic composite materials in which the filler phase can be manipulated to form a desired microstructure. This is performed via the application of an electric field to a colloidal suspension consisting of a filler material dispersed in a fluid polymer medium. Field induced dipole-dipole interactions cause particles to experience a mutual interaction resulting in distinct particle chains which align parallel to the applied electric field direction. This chained microstructure can then be "frozen in" by crosslinking the polymer matrix. The chaining phenomena is dependent on both the magnitude and the frequency of the applied field. Optimum assembly conditions for this process are determined via optical microscopy and electrorheological measurements. The dielectrophoretic assembly process also has the advantage of in-situ quality control through dielectric measurements. Both the degree of alignment and the batch uniformity can be confirmed via dielectric measurements. By varying the applied field and frequency, chain coarseness can be manipulated giving rise to the ability to "tune" the properties of the composite. The dielectrophoretic assembly process is projected to be utilized for electrical, structural and thermal composite applications.
Predictions of Static Displacements in 1-3 Piezocomposites
Authors: Li L. , Sottos N. R.
Published: August 2009

Piezocomposites have demonstrated higher sensitivity and lower mechanical losses than single phase piezoelectric materials. As with any composite material, the properties and behavior of piezocomposites are highly dependent on the properties of the constituent materials and the interface between them. In this paper, the micromechanical behavior of 1-3 piezocomposites is investigated. An analytical model is developed for predicting the static displacement behavior of a single piezoelectric rod embedded in a matrix. In the model, the ceramic rod is treated as transversely isotropic since it has different piezoelectric coefficients in the longitudinal and transverse directions. It is proposed that presence of a thin interlayer or polymer coating around the ceramic rods can influence the longitudinal displacement of the rods and change the overall sensitivity. A composite cylinder model is adopted to incorporate the presence of an interlayer with varying properties. Theoretical predictions indicate that the introduction of a compliant interlayer greatly increases the outof-plane displacement of the rod and the sensitivity of the composite.
On the Electromechanical Response of Electrically Active Materials
Authors: Jiang Qing
Published: August 2009

A continuum model is proposed to characterize the macroscopic behavior of ferroelectric materials undergoing an electrically-induced phase transformation. Within the framework of electromechanics, the author has investigated the feasibility of adjusting stresses within a ferroelectric device by applying an electric field to induce the paraelectric-ferroelectric transformation. The present analysis shows that the rate at which the stress can be adjusted is governed by a nonlinear ordinary differential equation which resulted from the kinetic relation that controls the evolution of the electrically-induced phase transformation. The present model, implemented with a numerical scheme, is able to predict the relation between the stress rate and the rate at which the electric field is applied. Some numerical results are included for illustration.
On Interphase Modeling for Optical Fiber Sensors Embedded in Unidirectional Composite Systems
Authors: Sirkis James S. , Lu I-Ping
Published: August 2009

This paper investigates the local stress of a polyimide coated optical fiber sensor surrounded by a transversely isotropic AS4-3501 graphite/epoxy host material. Spatially varying and spatially constant interphase composite cylinders models are used to understand the behavior of this system to longitudinal and radial normal, in-plane shear, and uniform thermal loading conditions. Interphase thicknesses used in the modeling effort are inferred from electron backscatter and scanning acoustic techniques. The results show that the gradient interphase models used in this paper are not warranted for this material system, that the thermal residual stresses in the core/cladding region can be significant, and that the optical fiber does not degrade the axial strengths of the composite, but the transverse tensile and compressive strengths are reduced by 15 and 60 percent respectively.
On the Interaction of Two Piezoelectric Fibers Embedded in an Intelligent Material
Authors: Honein T. , Honein B. V. , Honein E. , Herrmann G.
Published: August 2009

In this paper we are concerned with the problem of two circular piezoelectric fibers of different radii and distinct material properties, perfectly bonded to a host intelligent material, of infinite extent. The matrix material may be piezoelectric or nonpiezoelectric but, together with the fibers' materials, it possesses the symmetry of a hexagonal crystal in the 6 mm class. The system is subjected to electromechanical loadings (singularities) which produce out-of-plane displacement and in-plane electric fields, but are otherwise arbitrary.

Within the framework of the procedure of heterogenization, recently developed by the authors, the solution is sought as a transformation applied to the solution of the corresponding homogeneous problem (i.e., the problem of the host material occupying the full space and subjected to the same sources). The solution is formulated in a manner which leads to some exact results. Universal formulae are derived for the electromechanical field at the point of contact of two piezoelectric fibers. Some quantities which are invariant under the transformation, i.e., quantities which take the same values in the heterogeneous as in the corresponding homogeneous problems, are also discovered. The ramifications of this discovery are investigated. Moreover, the asymptotic behavior of the electromechanical field at the closest points of two plated circular holes or rigid conductors, approaching each other in an intelligent matrix material is also studied and given by universal formulae, i.e., formulae which are independent of the electromechanical sources. The interaction of the fibers with host-material microdefects, such as dislocations, electric line charges and microvoids, is scrutinized. The possibility of manipulating the electrical potential to reduce the high stress level is also discussed.
Panel Flutter Limit-Cycle Suppression with Piezoelectric Actuation
Authors: Lai Zhihong , Xue David Y. , Huang Jen-Kuang , Mei Chuh
Published: August 2009

An optimal control design is presented to suppress panel flutter limit-cycle motions using piezoelectric actuators. First, the nonlinear dynamic equations of motion based on the classical continuum method are derived for a simply supported isotropic panel with a pair of patched piezoelectric layers. After linearizing the dynamic modal equations, an optimal controller is developed to provide an optimal combination of inplane force and bending moments through piezoelectric actuators for flutter suppression. For the panel configuration studied, numerical simulations based on the nonlinear model show that the maximum suppressible dynamic pressure X,.,. can be increased about three times of the critical dynamic pressure Xc, by the piezoelectric actuation, and the bending moment is much more effective in flutter suppression than the inplane force. Within the maximum suppressible dynamic pressure, limit-cycle motions can be completely suppressed. For the actuator design, the two-set actuators perform better than the one-patched actuator, and the one-patched actuator, may have better performance than the completely covered actuator. The results demonstrate that piezoelectric materials are effective in panel flutter suppression.
Coaxing Predictable Behaviour from Unstable (Intelligent) Polymer Systems: Processing Dynamic Systems
Authors: Wallace Gordon , Spinks Geoff , Small Christopher , Eisazadeh Hossein
Published: August 2009

The development of intelligent polymeric materials is a multidimensional task. It requires the design of processing systems that retain dynamic properties meaning that the material produced is inherently "unstable". It also requires the design of communication tools that can be used to study, manipulate and control this dynamic character so as predictable, intelligent behaviour can be coaxed from these "unstable" systems.
A One-Dimensional Constitutive Model for Shape Memory Alloys
Authors: Barrett David John
Published: August 2009

This paper describes a constitutive model for the one-dimensional analysis of shape memory alloys. The model can treat thermal loads, mechanical loads, residual stresses and the temperature and phase change dependence of the material properties. Unique features of the model include phase change hardening, hysteresis with partial transformations and tensioncompression transformations. The model differentiates between stress induced and temperature induced transformation strains and introduces the importance of accounting for the tensioncompression phase change history. The paper discusses these features and presents several analytical predictions.
Active Mechanical Components as a Step towards Adaptive Structures in Space
Authors: Charon Willy , Baier Horst
Published: August 2009

Space missions require higher and higher performance such as high pointing accuracy and stability, and high shape precision. As a consequence the damping of in orbit vibraxtions induced, e.g., by the spacecraft manoeuvres on satellite appendages is mandatory. Passive damping becomes insufficient. More and more active technologies have to be considered. However project responsibles somewhat distrust these active technologies because of the technological risks which are still involved. This is the purpose of this paper to address the need for developing active mechanical components as a necessary step towards adaptive structures in space. The role of active interfaces is addressed in connection with typical applications will be particularly outlined. Two examples implementing an active interface are then more detailed:

• damping augmentation of solar arrays

• increasing the pointing stability of an inter satellite communication terminal The improvement of the static and dynamics behaviour of large reflectors is addressed in order to show the technological risk that requires intermediate development steps.
Global Multivariable Vibration Control with Distributed Piezoceramic Actuators
Authors: D'Cruz Jonathan
Published: August 2009

The topic of vibration control with distributed actuators has been the subject of much recent research. A technique by which the random vibration of a rectangular panel is controlled by means of a pair of thinsheet piezoceramic actuators is presented. Two accelerometers provide the feedback signals, which are processed digitally, according to a multivariable direct feedthrough feedback control law, to determine the control voltages. The control law design process decouples the feedback system into two actuator/sensor pairs. The procedure used to determine actuator and sensor locations, based on the modes to be controlled, is discussed. The method employed to select model orders and optimise feedback gains is also described. Finally, experimental results which demonstrate that significant reductions in vibration levels are achieved globally are presented.
Control of Flexible Structures by Distributed Piezofilm Actuators and Sensors
Authors: Choi Seung-Bok , Cheong Chae-Cheon , Kim Seung-Han
Published: August 2009

This paper presents control algorithms to suppress flexural vibration of a cantilever beam using distributed piezofilm actuators and sensors. A modified constantamplitude controller is proposed to overcome practical drawbacks associated with conventional constantamplitude and constantgain feedback controllers. The proposed controller is established on the basis of the velocity signals as well as the oscillation magnitudes of the beam. Computer simulations and experimental tests are undertaken in order to compare suppression capabilities between the proposed and conventional control algorithms. In addition, simultaneous controllability of various vibrational modes under random excitation is experimentally verified.
Determination of Design of Optimal Actuator Location and Configuration Based on Actuator Power Factor
Authors: Liang C. , Sun F. P. , Rogers C. A.
Published: August 2009

In this paper, a new design algorithm is proposed for optimization of the inducedstrain actuator location and configuration for active vibration control based on an actuator performance index, namely the actuator power factor. The concept of actuator power factor, developed recently by the authors, describes the capability of an integrated induced strain actuator, such as PZT or Terfenol, to transfer the supplied electrical energy into structural mechanical energy (kinetic or potential energy of the mechanical system). A system optimized based on the actuator power factor will guarantee the highest energy efficiency for single frequency and broad-band applications. This paper will also show that a higher energy efficiency corresponds to higher mechnical performance. The approach introduced in this paper is much more convenient to use than the conventional modal domain optimization approach. Furthermore, since the power factor approach can include the electrical parameters from the power system, it will allow a system optimization design including the power electronics and energy consumption.

The basic concept of the actuator power factor will be introduced first in this paper. Its utility in the system optimization will be discussed using a PZT actuator-driven simply-supported beam. The optimization of actuator location, length, and thickness will be discussed through numerical examples. This paper will also discuss how to use the actuator energy density and actuator power factor to estimate the dynamic response of a system.
Feasibility Study of a Torsional-Bending Piezoelectric Actuator
Authors: Kawiecki Grzegorz , Smith Winthrop P. , Hu Chenyi
Published: August 2009

The objective of this paper is to show the feasibility of a novel actuator capable of inducing torsional, bending and longitudinal control loads in a thin-walled structural member using piezoelectric elements. Torque is generated by extension/compression action of a set of piezoelectric elements surface bonded to the walls of a structural element. The same set of elements may be used to control torsional, bending and longitudinal vibrations. Analytical and experimental validations of the concept are presented.
Efficient Integration of the Time Varying Closed-Loop Optimal Control Problem
Authors: Smith H. Allison , Chase J. Geoffrey , Wu Wen-Hwa
Published: August 2009

Much of the research done in recent years towards the development of the smart or adaptive structure focuses on the application of active control to alleviate undesirable structural responses. However, classical optimal control algorithms are not directly applicable to most structural engineering applications because the control gains, obtained by solving the matrix differential Riccati equation (DRE), neglect the effects of the external forcing function and assume a time invariant system (which allows the DRE to be reduced to an algebraic Riccati equation). Due to these simplifications, the control algorithm loses its optimality and consequently may induce significant control inefficiency.

In this study, a matrix-valued integration procedure is formulated for and applied to the differential Riccati equation with time variant plant and weighting matrices. The ability to effectively integrate the time variant differential Riccati equation allows the control algorithm to adapt to changing structural parameters. Examples are presented which apply this new procedure to solve the control equations associated with a five story, tendon-controlled shear building with time variant stiffness and damping matrices.
Recursive Estimation of Displacement and Velocity in a Cantilever Beam Using a Measured Set of Distributed Strain Data
Authors: Gopinathan Murali , Pajunen Grazyna A. , Neelakanta P. S. , Arockaisamy M.
Published: August 2009

A new form of recursive algorithm to estimate the transverse and angular displacement and/or velocity at any location along the length of a one-dimensional cantilever beam using the strain/strain-rate data measured from a set of sensors distributed along the length of the beam is presented. This is based on the linear spline functions used to approximate the strain distribution in the beam. One of the main applications of this algorithm is in controlling the vibrations in a flexible cantilever beam. To demonstrate its use in such a problem, a linear quadratic regulator (LQR) algorithm is considered and the recursive algorithm stated earlier is used for the state estimation which can be used in conjunction with the state feedback controller. Experimental results for both static and dynamic cases are furnished to validate the proposed estimation algorithm. In the case of static loading, strain gauges are used to measure the strain, while piezoelectric sensors are used in the dynamic case. Results showing the performance of the control algorithm that utilizes the recursive algorithm developed are presented.
Shape Control of Inflatable Reflectors
Authors: Utku S. , Kuo C. P. , Garba J. A. , Wada B. K.
Published: August 2009

In this work studied are the means of maintaining the target design geometry of inflatable membranes that are used for low frequency antenna collectors. Considering the deviations from the target state as the linear combinations of a set of given n normalized undesirable displacement patterns (e.g., Fourier-Zernike functions), the linearized thin shell and membrane theories are used to obtain expressions for the components of the corresponding n number of induced macro strain states. Then the problems associated with the failure in implementing by piezofilm actuators all the components of the geometrically compatible macro strain states are studied. As a result of these studies several recommendations are given.
Energy-Based Comparison of Solid-State Induced-Strain Actuators
Authors: Giurgiutiu Victor , Rogers Craig A. , Chaudhry Zaffir
Published: August 2009

A study of published literature and information from piezoelectric, electrostrictive, and magnetostrictive actuator vendors has been undertaken to establish the mechanical and electrical operating characteristics of the actuators, and to compare them using output energy density criteria. Output energy values of up to 0.666 J can be achieved with off-the-shelf actuators. Energy density per unit volume was found in the range 1.816-7.280 J/dm3. Energy density per unit mass was found in the range 0.233-0.900 J/kg. In one isolated case, higher energy densities of 11.9 J/dm3 and 1.09 J/kg were identified for a small co-fired PMN stack of 0.00481 J total energy. Energy transformation efficiency between input electric energy and output mechanical energy was found to be: 17-27% for adhesively-bonded PZT and PMN stacks, 5-20% for co-fired PZT and PMN stacks, and 67.1% for TERFENOL-D devices. The overall performance of induced-strain actuators based on output energy density criteria was found to vary widely from vendor to vendor, and even from one model to another within the same vendor catalogue list. These variations are attributed to progress being made currently in both the active material technology and in the detailed mechanical construction of induced-strain actuators based on these materials.
Application of Mechanical Waves Induced by Piezofilms to Marine Fouling Prevention
Authors: Rahmoune Miloud , Latour Mireille
Published: August 2009

The complete set of equations for describing the mechanical and electrical behavior of a piezoelectric medium is given. From these equations, the electromechanical equations describing the dynamical behavior of PVDFS and their mounting plate are derived. The electromechanical equations are used to explain antifouling process with the PVDFs as actuators. The transverse displacement is calculated using the electromechanical equations and compared with the experimental results. A comparison of the transverse displacement of the plate as a function of the applied PVDF voltage with the corresponding experimental case shows a good agreement. First, the optimal acceleration necessary for the antifouling marine prevention is found to be approximately 0.2 g by optical spectroscopy. Second, the activation energy and cycle of the PVDF actuators are determined.
Experimental Investigations on Tension and Compression Properties of an Electro-Rheological Material
Authors: Haiqing Gong , King Lim Mong
Published: August 2009

This work is concerned with experimental investigation on properties of an electrorheological fluid subjected to static and dynamic tensile and compression loading. The electric voltage is kept constant during the tests and the initial electric field strength ranging from 0.5-5 kV/mm is generated to observe its influence on the stress-strain curves in compression and tension. Glass fibre is also added to investigate its effect on strength of the ER fluid. In addition, strain rates of 0.5 mm/min and 1 mm/min are imposed to investigate behaviors of ER fluid under the dynamic tensile loading condition.

Experimental results from this work reveal that the yield strength in tension and peak stress level in compression are an order of magnitude higher than those in shear. The results also show that the yield stress and Young's modulus of the ER fluid in the absence of the fiber increase with electric field strength in the tensile test with a dynamic load. Beyond the yield point in a tensile test with the fiber, the stress is maintained at a significantly high level over a large range of strain, which indicates a high toughness of the ER fluid in tension. Addition of the fiber content also helps to increase significantly the yield stress and tensile strength. In addition, with addition of the fiber to the ER fluid, the Young's modulus becomes insensitive to electric field.
Solid-State Actuation of Rotor Blade Servo-Flap for Active Vibration Control
Authors: Giurgiutiu Victor , Rogers Craig A. , Rusovici Razvan
Published: August 2009

The basic concepts and some innovative ideas associated with the analysis, design, and experimentation of induced-strain actuators for rotor blade aeroelastic vibration control are presented and discussed. A trailing-edge servo-flap actuated by a hydraulically-amplified large-displacement induced-strain actuator is considered. Design requirements based on extensive literature review are proposed and utilized. The principle of high-power induced-strain actuation, and the energy and energy-density of several commercially-available induced-strain actuators are presented. A full-scale proof-of-concept demonstrator, designation HAHDIS Mk. 1, was designed, built, and tested. Results from static and dynamic tests are presented and discussed. Good frequency response of the full-scale proof-of-concept demonstrator was proven in the range of 1 to 30 Hz in spite of the power and current limitations of the available electronic equipment.
Performance of a Smart Vibration Isolator for Precision Spacecraft Instruments
Authors: Regelbrugge Marc E. , Carrier Alain , Dickson William C.
Published: August 2009

This paper describes the configuration and measured performance of an hybrid, active-passive vibration isolation mount designed to mitigate vibratory disturbances on sensitive spacecraft instruments. The device, called the Active Vibration Canceler (AVC), consists of a passive isolation stage using composite leaf springs faced with shape-memory metal sheet material to provide load-adaptive damping, and an active, force-canceling stage using a motion-amplified electrostrictive stack actuator to augment attenuation of transmitted vibrations in the 10-120 Hz band. The paper discusses the features of the AVC design and active control architecture, and presents results of experiments characterizing the broadband performance of the device. Performance measurements show that the AVC provides up to 40 dB attenuation of base disturbances at 100 Hz, and that the electrostrictive active stage provides in excess of 10 dB attenuation over the passive isolator in the range 10-100 Hz. The measurements indicate that hybrid devices of this type can be effective in reducing transmitted vibrations to sensitive instruments, and that the incorporation of active elements can significantly enhance attenuation of broadband vibrations in isolation applications.
Powder Particle Manipulation and Assemblage Using Microprobe
Authors: Egashira Mitsuru , Konno Takeshi , Shinya Norio
Published: August 2009

Powder particle manipulation and welding techniques using a microprobe have been developed for use of microassembling. These techniques were applied to fabrication of microstructures by assembling powder particles. For the microprobe, a needle with a tip of 2 Am in diameter was prepared. Au and Ni alloy powder particles of about 60-100 Jim diameter were used for the manipulation and welding experiments.

The experiments showed that Au powder particles can be easily picked up, moved to a predetermined point and deposited at the point by controlling the voltage between the W microprobe and the substrate. Furthermore, the powder particle can be welded into the substrate or other powder particles on the substrate by glow discharge between the tip of the probe and the substrate. By utilization of the powder particle manipulation and welding, microstructures composed of Au and Ni alloy powder particles were fabricated. It was demonstrated that the microprobe technique is very useful for the fabrication of micromachines and microdevices. Also, the technique is thought to be useful for the creation of intelligent materials.
Control of Temperature Distribution at Cylinder Surface by Magnetic Fluid
Authors: Krakov Mikhail S. , Kamiyama Shinichi
Published: August 2009

The present study deals with the influence of a magnetic fluid coating, held onto a circular cylinder surface by a magnetic field, on the temperature distribution at the surface of a cylinder heated by a constant heat flux. The temperature distribution over the cylinder surface in the fluid is determined by the heating power of the cylinder and the incoming flow structure. The flow structure near the cylinder can be changed by applying a magnetic fluid coating over its surface and by holding it with a magnetic field. In this case, heat from its surface to the external flow is removed by two modes. First, the heat is transferred to the external flow due to heat conduction of the magnetic fluid. Second, the heated layers of the magnetic fluid are entrained due to circulation and give up their heat to the external flow at the interface. Thus, there are two mechanisms of removing the heat inside the magnetic-fluid coating: conductive and convective. The balance of these two mechanisms is determined by the circulation intensity inside the coating and by the value of magnetic fluid thermal conductivity.

A steady laminar flow of viscous fluid past a circular cylinder with magnetic fluid kept on its sur-face under a magnetic field is investigated numerically by finite-element method. A grid of 5751 nodes is used. The cases of Reynolds number Re = 10, 30, 100 are considered. The role of heat conduction ratio is determined for the meanings A = 0.1, 1, 10.

The great influence of magnetic fluid coating on surface temperature distribution is discovered in the paper. The distribution can be profitably varied by the magnetic fluid properties and flow velocity: it can be nonmonotonic, and the temperature of a solid can increase in the direction opposite to the direction of fluid flow.
Steerable Microcatheters Actuated by Embedded Conducting Polymer Structures
Authors: Santa A. Della , Mazzoldi A. , de Rossi D.
Published: August 2009

Steerable microstructures, i.e., catheters, are presented. They exploit the electromechanochemical phenomena of ir-electron conjugated conducting polymers occurring when ionic species are exchanged with the surrounding medium. In this paper we considered polypyrrole as conducting polymer and a fast ionic conductor solid polyelectrolyte as ionic reservoir. Experimental determination of the governing material constants, modelling of conducting polymer/solid polyelectrolyte composite material and finite element computer simulations of the mechanical properties of cylindrical structures provide favourable indication about the feasibility of effective steerable, miniaturised catheters.
Deflection Shape Control of a Flexible Beam by Using Shape Memory Alloy Wires Under the Genetic Algorithm Control
Authors: Nagaya Kosuke , Ryu Homin
Published: August 2009

This paper presents a method for controlling a deflection shape of a flexible beam by using shape memory alloy wires. The analytical solution for the deflection of the beam under the austenite transformation of the wires was obtained first, then a method for controlling the deflection shape was discussed on the basis of the genetic algorithm. Numerical calculations were carried out for some typical examples. It is clarified that the present system and the control method are applicable to the deflection control of flexible structures.
Recent Research on Intelligent Materials
Authors: Takagi Toshinori
Published: August 2009

Intelligent materials are the materials possessing functions in themselves such as the sensing function which detects the environmental change or their inner anomaly, the processor function which can judge the situation to lead the conclusion, and the actuating function which activates the materials within themselves to take action or give instruction.

The structural and functional materials simply utilize the native properties and functions of their own. On the other hand, the intelligent materials are based on a new concept where the information science will be united with their own properties and functions. The intelligent materials are very important and useful in many fields and the interdisciplinary fields such as the medicine, pharmacy, bioengineering, polymer, metallurgy, semiconductor, ceramics, electronics, and machinery. It is also an extremely important material in human engineering, safety engineering, environmental research, and for study of the resources.

In this report, the category of the intelligent material and the recent activities of research on the intelligent materials are discussed.
Adaptive Lightweight CFRP Strut for Active Vibration Damping in Truss Structures
Authors: Schotze Rainer , Goetting Hans Christian
Published: August 2009

For the purpose of active damping and suppression of vibration in advanced composite truss structures a new adaptive lightweight strut was developed. It was based upon a previously developed multi-purpose CFRP sandwich strut with integrated load transfer elements. Into this strut. which exhibits excellent mechanical properties related to the structural weight. a piezoceranmic highload stack actuator with an expansion capability of 55 Itm was integrated. A special design using a composite sleeve allows the tailoring of the strut stiffness particularly with respect to high active tension forces. The measurement of the dynamic strut response is provided by a surface bonded and electrically isolated PVDF film sensor. Tests of the adaptive strut in an antenna-supporting composite truss structure established a nearly complete suppression of externally excited disturbing vibrations. Due to the structural concept the new adaptive strut is well suited for active vibration control under high strength and stiffness requirements.
A Non-Linear Model for Dynamic Response of Electro-Rheological Fluid in Flow Mode
Authors: Firoozian R.
Published: August 2009

In this paper a model is presented for the electrical and mechanical properties of ER fluid in flow mode and it is concluded that a similar model must also govern the properties of ER fluid in shear mode of operation. A settling time constant is defined for the fluid which determines the speed of response. The model has been derived from several years of experience gained working with ER fluid and has not been verified experimentally. The proposed model is based on the theory that the electrical properties of ER fluid such as resistance and capacitance are functions of the applied voltage and time. This function is characterised by a time constant (TR) for a simple model and may be characterised by a natural frequency and a damping ratio for more complex model. The numerical solution of these functions when compared with the experimental results obtained from large step input confirm the viability of the proposed model. Further work, however, is required to identify the coefficients numerically from data obtained on a special test rig.
Structure and Interaction Force in a Model Magnetorheological System
Authors: Tang X. , Chen Y. , Conrad H.
Published: August 2009

The force-displacement behavior of specific arrangements of 1.6 mm dia. steel spheres in a magnetic field of 4.2 kGs was determined in tension and shear. The maximum attractive stress between the particles in a single-row chain in tension was 411 kPa, independent of the number of spheres in the chain beyond four. The shear stress r-strain oy curve of a single-row chain exhibited a single peak with raX = 248 kPa at a shear strain -y = 0.32, providing the spheres in contact with the magnet walls were glued in position. Without gluing slippage of a chain or cluster occurred during shearing, giving a maximum stress only about 1/6 that without slippage. The r vs -Y curves for clusters of particles exhibited multiple peaks which corresponded to the movement of the spheres in breaking and reforming bonds. The maximum tensile and shear stresses tended to be smaller for clusters compared to equivalent single-row chains when the number of particles in a row is small.
The Peculiarities of Relaxational Processes in Active Cellulose Fillers for Electrorheological Media
Authors: Lazareva T. G.
Published: August 2009

The peculiar features of relaxation processes in active cellulose fillers are elucidated using the dipole relaxation method, the measurements being made in a frequency range from 10 to 103 Hz at temperatures from -100 to + 100C. A hypothetical model of structural changes in a cellulose matrix due to the introduction of ionogenic acidic groups is proposed. A possibility is shown of controlling polarization processes in such structures by applying electric fields of variable strength at room temperature.
Applications of Electro-Rheological Fluids for Constrained Layer Damping Treatment of Structures
Authors: Oyadiji S. O.
Published: August 2009

Constrained layer damping (CLD) technique employs solid viscoelastic materials for controlling the vibration characteristics of structures. The effectiveness of the CLD treatment depends on the dynamic mechanical properties and geometrical dimensions of the viscoelastic and constraining layers. It also depends on the percentage coverage of the structure by the viscoelastic and constraining layers. Since the complex dynamic properties of electro-rheological (ER) fluids vary between those of viscoelastic liquids (at low levels of electric field strengths) and those of viscoelastic solids (at high levels of electric field strengths), ER fluids can be used in an adaptive form for CLD applications. The results of experimental and analytical studies on the vibration characteristics of a clamped-clamped plate which is partially and totally filled with an ER fluid are presented. The ER fluid employed is a mixture of 50 wt% of an analytical reagent grade of starch dissolved in 50 wt% of a silicone oil. It is shown that for the particular ER fluid utilised, the variations of the frequency response functions and the modal parameters of the composite plate are more strongly dependent on the location and size of the ER fluid CLD treatment than on the electric field strength.
Effective Viscosity of an Electrorheological Fluid
Authors: Sun J. M. , Tao R.
Published: August 2009

The viscosity of an electrorheological fluid in an electric field is studied by computer simulations. The fluid viscosity increases with the field through three stages. In a weak field, the fluid remains Newtonian although its viscosity increases. At this stage, while drifting in the flow direction, particles diffuse in the direction perpendicular to the flow. In an intermediate electric field, the fluid has tilted and broken chains moving with the flow and the fluid becomes non-Newtonian. The viscosity -q and the shear rate j has the following relationship -q = 'qoc-8 where T is the relaxation time and -go is exponentially proportional to the dipolar interaction energy and the volume fraction. In a strong electric field, the fluid contains condensed chains which provide yield stress and hysteresis.
Variation with Distance of the Attraction Force between Spheres and Estimation of Static Yield Stress of ER Fluids
Authors: Atten P. , Boissy C. , Foulc J. -N. , Zhu K. Q.
Published: August 2009

In order to estimate the static yield stress of a suspension of monodispersed spheres subjected to a DC applied field, the knowledge of the interaction force between spherical particles is required. This question of variation of the attraction force between spheres as a function of their distance is investigated on the basis of the conduction model in the particular case of saturation regime of bulk electrical condition of the liquid. The prediction is tested using a scaled-up twosphere experimental model for the particles interaction. Then a rough estimate of the static yield stress is derived using a linear approximation of the force dependence of the spacing s between spheres.
Effects of Cell Confinement on the Evolution of Field-Induced Structures in a Magnetorheological Fluid
Authors: Liu J. , Mou T. , Zhu Y. , Haddadian E. , Pousset J. , Lim S. R.
Published: August 2009

The evolution of field-induced structure in ferrofluid emulsions is studied during the "gas-solid" phase transition. The chain formation and coarsening are measured by monitoring the average separation between aggregates d using static light scattering and optical microscopy. A powerlaw relation, d -tr, is obtained for all measured cell thicknesses ranging 10 c L c 700 jim along the field direction. The rate of chain coarsening strongly depends on the chain length, weakly depends on the particle volume fraction and is independent of the field strength at a finite cell thickness. A theoretical model based on thermal fluctuation induced coupling and nucleation theory has been developed to explain the data at large L successfully.
Rheology of a Magnetorheological Fluid
Authors: Felt D. W. , Hagenbuchle M. , Liu J. , Richard J.
Published: August 2009

We report on experimental investigations of the rheological behavior of aqueous magnetic suspensions. The suspended particles are monodisperse colloidal polystyrene spheres which contain magnetic Fe203-grains. In the absence of a magnetic field these suspensions behave as Newtonian fluids, whereas under the influence of a magnetic field due to the formation of an ordered structure the apparent viscosity of the suspension increases up to three orders of magnitude and they clearly exhibit non-Newtonian properties, such as shear thinning and yield stress. The apparent viscosity depends on the magnetic field according to aq - H2". Increasing the volume fraction of the particles in the range of 0.014 < 0 < 0.12 results in a linear increase in apparent viscosity and yield stress. Both apparent viscosity and yield stress depend also on the particle size as first measurements on particles with diameters ranging from 0.5 Am to 1.0,Am clearly show. All measurements were carried out with a rotation viscometer using the cone-plate configuration so that the applied shear rate was well defined.
Analysis of Controlled Beam Deflections Using SMA Wires
Authors: Brinson L. C. , Huang M. S. , Boller C. , Brand W.
Published: August 2009

In this paper the active control of beam deflection through heating and cooling of Shape Memory Alloy (SMA) wires is examined. A phenomenological constitutive law for SMA wires is coupled with beam theory to provide predictions of beam shape upon temperature change in the SMA actuator. Both the linear and nonlinear beam theory are presented, enabling calculation of large deflections. Examples for a single wire attached at the tip of a uniform beam are given, but the procedure can easily be generalized for other configurations and utilized in control algorithms. Issues of design constraints for shape control with shape memory wires are addressed and the model is qualitatively verified by experiments.
Modeling of SMA Tendons for Active Control of Structures
Authors: Shahin Alu R. , Meckl Peter H. , Jones James D.
Published: August 2009

The use of shape memory alloy (SMA) wires as active tendons to reduce vibra-tion of a building model is analytically investigated. Approximate dynamic equations for one bay of a multi-story building with SMA tendons are derived based on laws of thermodynamics and Brinson's constitutive equations. These equations are used to provide comparisons between us-ing SMA tendons passively and active for vibration control. In this model, the modes of transfor-mation considered are austenite to martensite (and detwinned martensite), martensite to detwinned martensite and martensite to austenite. In the active case, the wire opposing the direc-tion of the floor mass displacement is heated by passing a current through it to take advantage of the thermomechanical properties of SMAs. The current to a wire is shut off as soon as the tendon is 100% austenite. In the passive case, no current is supplied to the wire. A numerical integration program was developed to include internal and potential energy changes, input work into the ten-dons, and energy transfers associated with the latent heat of transformation. In this program, for numerical stability of the subroutine used, the current is shut off to the tendon as soon as the martensite volume fracture of that tendon goes below 0. 1%. Displacement profiles are presented for both the passive and active implementations of the SMA wire. Simulation results show a fac-tor of twelve improvements in steady state tracking error between the first floor and the base of the model structure when the tendons are used passively. The results are further improved by a factor of seven when the tendons are used actively. Also the effect of different cooling rates is ex-amined. Comparing tracking errors for the system using free convection and convection coeffi-cients of 80 and 100 W/m2K, it is shown that lower cooling rates can result in a reduction in tracking error.
Investigations of the Nonlocal Exchange Energy Model on a Single Body of Ferromagnetic Material
Authors: Keane Michael K.
Published: August 2009

In this paper we do computations on a single spherical body of uniaxial ferro-magnetic material in a varying applied magnetic field. Our computations are based on a relaxed model with a nonlocal exchange energy. The model is based on Young-measures, but we will make use of recent calculations which indicate that our computations can be based on only the first and second moments. We extend the result of a single uniaxial sphere in a uniform applied magnetic field parallel to the easy direction of magnetization to uniform applied magnetic fields that are skew to the easy direction of magnetization. We show that when the exchange energy is zero, we duplicate the wide range of measured-value minimizers of De Simone's model. As the exchange energy grows, our model stabilizes at the saturated solutions of the Stoner-Wohlfarth model where the measured-valued minimizers are eliminated.
Experimental Evaluation of Segmented Active Constrained Layer Damping Treatments
Authors: Kapadia Rajiv K. , Kawiecki Grzegorz
Published: August 2009

The objective of this research is to demonstrate the effect of Active Constrained Layer segmentation on the enhancement of low frequency vibrations damping in flexible beams. The Active Constrained Layer Damping treatment, under consideration, consists of a viscoelastic layer sandwiched between two piezoelectric layers. The shear deformation of the viscoelastic layer causes loss of energy and thus the damping of vibration.

This paper focuses on the effects of constraining layer segmentation. Experimental results obtained for slender beams partially treated with segmented and unsegmented Active Constrained Layer Damping treatments are presented. Tested specimens have low natural frequencies typical. e.g., for long span floors, moment frames, or flexible robotic manipulator arms. The performance of segmented and unsegmented treatments, as well as active and passive treatments are compared. The presented results demonstrate that significant improvement in Active Constrained Layer Damping treatment performance can be achieved by an appropriate segmentation of the constraining layer.
Adaptive Shape Control of Composite Beams with Piezoelectric Actuators
Authors: Chandrashekhara K. , Varadarajan S.
Published: August 2009

This paper deals with adaptive shape control of laminated composite beams with integrated piezoelectric actuators. The mathematical model is based on a higher order shear deformation theory and accounts for lateral strains. A constrained optimization algorithm has been implemented to calculate the optimal open loop actuator voltages which minimize the error function. A closed loop feedback system is developed to maintain the desired shape even in the presence of quasistatically varying unknown loads. A computationally efficient finite element code is developed for performing the numerical calculations. The effect of stacking sequence and boundary conditions on the actuator voltages for both open loop and closed loop systems is examined. It is observed that the adapted shape achieved by using a full sensor feedback and partial sensor feedback are nearly the same. Thus position sensors at all locations are not required for closed loop shape control.