bluuebunny/crossref_metadata_2025 huggingface dataset:
Cancellation of Periodic Forces with Solid-State Actuators
Authors: Schafer Jurgen , Janocha Hartmut
Published: August 2009

Due to their specific properties (high forces and speed), new solid-state actuators with piezoelectric or magneto-strictive transducers can be used in active damping systems to realize mechanical structures with controllable stiffnesses. One possible application is the damping of undesired periodic vibrations produced by rotating engines. The vibrations can be measured by an accelerometer, and a digital signal processing unit calculates the appropriate actuating signal to control the mechanical structure. The authors present a new procedure that uses a very simple recursive short-time autocorrelation (ACF) algorithm and a least mean squares (LMS) algorithm to calculate the control signal. The short-time ACF determines the periodicity of the vibration signal. It uses an exponentially decreasing weight function. The time constant of this function can easily be adapted to the dynamics behaviour of the mechanical process. The LMS algorithm performs the synthesis of the actuating signal. It adapts the amplitude and phase of a harmonic signal with the determined frequency. The stability of the system can be verified by a maximum adaptation rate criteria. The procedure still works with nonlinear transfer functions of the actuator, mechanics or sensor. Experiments with a magnetostrictive actuator showed a damping of the acceleration amplitude of up to -37 d B.
Some Recent Advances in Linear and Nonlinear Dynamical Modeling of Elastic and Piezoelectric Plates
Authors: Yu Y. Y.
Published: August 2009

A previous review has covered our early efforts in dynamics and vibration of homogeneous and layered elastic plates and shells, including sandwiches. As an update, the present review summarizes our recent efforts in the same general area, now further including laminated composite and piezoelectric plates. These reflect the increasing importance of laminates, the growing interest in distributed active vibration control through the use of piezoelectric layers and often a combination of both. The main purpose of this paper is to again provide a systematic overview of linear and nonlinear dynamical modeling of both homogeneous and layered plates. As many of our contributions have been made by means of the variational equations of motion in three-dimensional elasticity and piezoelectricity, an extended discussion of these equations is included as an integral part of this review. Recent applications of these to the linear and nonlinear dynamical modeling of elastic laminates and piezoelectric layers are described.
A Theoretical Framework for the Analysis of Thermoelectroelastic Heterogeneous Media with Applications
Authors: Dunn Martin L.
Published: August 2009

A rigorous theoretical framework is presented for the analysis of thermoelectroelastic heterogeneous media. These materials include, among others, piezoelectric composite media which exhibit pyroelectricity. Formal definitions of a representative volume element, phase constitutive behavior, and numerous averaging theorems are presented. Expression for the average fields in the constituent phases in terms of thermal and electroelastic concentration factors are presented as are exact expressions for the effective moduli in terms of the concentration factors. An approach is presented to estimate the phase concentration factors which is based on the rigorous solution for the auxiliary problem of a single piezoelectric inhomogeneity embedded in an infinite matrix (which is also outlined). The theoretical principles are presented in the framework of a convenient 9 x 9 and 9 x 1 matrix formulation which greatly simplifies their numerical implementation. The framework presented here allows for the clean delineation between exact and assumed relations and allows a clear interpretation of all assumptions. Applications are made to polycrystalline piezoelectric ceramics, cracked piezoelectric solids, and two-phase piezoelectric composites.
An Iterative Finite Element Procedure for the Analysis of Piezoelectric Continua
Authors: Gaudenzi Paolo , Bathe Klaus-Jurgen
Published: August 2009

In this paper an iterative finite element procedure is presented for the analysis of twoand three-dimensional piezoelectric continua. The procedure is applied to the steady-state analysis of two-dimensional media subjected to mechanical and electrical loading.
Design of a Fuzzy Controller for Adaptive Truss Structures
Authors: Tsou Poyu , Shen M. -H. Herman
Published: August 2009

An entire treatment of designing a fuzzy control system for kinematical movements of adaptive truss structures is presented. The truss structure is constructed by stacking a series of basic structural modules which are individually controlled by the modular fuzzy controllers. A systematic way of achieving the modular fuzzy controller design is presented, which allows one to formulate the fuzzy rules by utilizing the inverse kinematics relationship of the basic structural module. The effects of selection of input/output gains, noises in measurement, and possible actuator failures are examined. The results show the proposed approach has several advantages.
Coupled Layerwise Analysis of Composite Beams with Embedded Piezoelectric Sensors and Actuators
Authors: Saravanos D. A. , Heyliger P. R.
Published: August 2009

Unified mechanics are developed with the capability to model both sensory and active composite laminates with embedded piezoelectric layers. Two discretelayer (or layerwise) formulations enable analysis of both global and local electromechanical response. The first assumes constant through-the-thickness displacement, while the second permits piecewise continuous variation. The mechanics include the contributions from elastic, piezoelectric and dielectric components. The incorporation of electric potential into the state variables permits representation of general electromechanical boundary conditions. Approximate finite element solutions for the static and freevibration analysis of beams are presented. Applications on composite beams demonstrate the capability to represent either sensory or active structures, and to model the complicated stressstrain fields, the interactions between passive/active layers and interfacial phenomena between sensors and composite plies. The capability to predict the dynamic characteristics under various electrical boundary conditions is demonstrated. Some advantages of the variable transverse displacement formulation on the freevibration response of sensory structures are also shown.
Heat Generation, Temperature, and Thermal Stress of Structurally Integrated Piezo-Actuators
Authors: Zhou Su-Wei , Rogers Craig A.
Published: August 2009

While converting electrical energy into mechanical energy to actuate structures, piezoelectric (PZT) elements experience a temperature increase due to internal heat generation caused by their mechanical damping and dielectric loss. In practice, if the actuation is operated at system resonance or with a relatively high electrical field, the heat generation throughout PZT actuators may be significant. The temperature rise of PZT elements may result in the acceleration of material aging, even thermal damage. The situation becomes worse if the actuated host structures are made of thermalresistant materials, such as polymeric matrix composites and glass. In addition, the temperature distribution in PZT elements induces thermal stress that may increase the overall stress level and reduce the maximum safe stress. However, investigations done to date on these issues have been limited. This paper presents a simple analytical approach to estimate temperature rise and thermal stress in PZT patch actuators due to dynamic excition. A onedimensional heat transfer model is developed for integrated PZT/plate structures. The temperature field of the PZT actuators is analytically found and the corresponding thermal stress is predicted. To determine the internal heat dissipation in PZT actuators, an electromechanical impedance model developed by the authors is directly applied. The dissipative power in the systems, consumed by mechanical damping and dielectric loss of the PZT actuators, and structural damping of the host structure, is first determined. The dissipative power is then treated as the equivalent thermal dissipation to create a distributed heat source throughout the PZT actuators and host structures. In the case studies, the PZT patch elements were used to actuate a simplysupported plate. The impact of the thermal stress on the overall stress level is discussed in the paper. The effects of actuator thickness and material properties on the actuator temperature and the thermal stress level have also been investigated.
Experimental Verification of Optimal Actuator Location and Configuration Based on Actuator Power Factor
Authors: Bhargava Adesh , Chaudhry Zaffir , Liang Chen , Rogers Craig A.
Published: August 2009

The actuator power factor is defined as the ratio of the total dissipative mechanical power of a PZT actuator to the total supplied electrical power to the PZT actuator. If measured experimentally, it can be used to optimize the actuator location and configuration for complex structures. The concept of actuator power factor is based on the ability of an integrated induced strain actuator such as a PZT to transfer supplied electrical energy into structural mechanical energy. For a given structure such as a beam or a plate, the location and configuration of an actuator will directly influence the authority of the actuator towards driving the structure. Presented in this paper are the experimental as well as the theoretical results for the case of a cantilever beam as a proof-of-concept of this technique. The design of a fixture which allows for the relocation of a PZT patch which can be used for both actuation and sensing is presented as well. For the experimental case, the electromechanical PZT admittance was measured by an HP 4194A impedance analyzer for the power factor analysis. The experimental and the theoretical power factor results were subsequently compared and showed good qualitative similarities over the frequency range analyzed. This initial comparison between the experimental and the theoretical power factor results will be used to analyze the capabilities and limitations of the actuator power factor algorithm as a tool for determining the optimal configuration and location for a PZT actuator for simple as well as complex structural vibration control applications.
Metal-Ceramic Composite Transducer, the "Moonie"
Authors: Onitsuka Katsuhiko , Dogan Aydin , Tressler James F. , Xu Qichang , Yoshikawa Shoko , Newnham Robert E.
Published: August 2009

A new type of metal-ceramic composite transducer, the "moonie,' has been developed by sandwiching a poled lead zirconate titanate (PZT) ceramic between two specially designed metal end caps. Piezoelectric coefficients an order of magnitude larger than PZT itself are obtained. The metal-ceramic composites are being developed as fish finders, hydrophones, actuators, and transducers with integrated sensing and actuating capabilities. This paper describes the moonie principle, optimization of the moonie design using finite element analysis, and the performance of the device for several different applications.
Vibration Control of a Cylindrical Shell Using Distributed Piezoelectric Sensors and Actuators
Authors: Qiu Jinhao , Tani Junji
Published: August 2009

This paper presents a study on vibration control of a cylindrical shell using distributed piezoelectric sensors and actuators which are parts of the shell wall. Modal expansion method is used in establishment of the state equation of the system. The robust control including JO. control theory and A-synthesis method are applied to the design of the controller which satisfies given control performance and robust stability. Simulation and experiment are carried out when the shell is excited at the resonance frequency of a controlled mode. The results show good agreement between simulation and experiment, as well as the effectiveness of the method using distributed sensors and actuators, and qK0. control theory and t-synthesis method.
Variation of Electrical Resistance and the Elastic Modulus of Shape Memory Alloys under Different Loading and Temperature Conditions
Authors: Carballo M. , Pu Z. J. , Wu K. H.
Published: August 2009

Shape memory alloys (SMA) have recently been proposed and demonstrated for several active control applications. However, there is only limited experimental information available on the properties of the SMA. The present paper focuses on variations of the dynamical Young's modulus, the damping characteristics, and the electrical resistance as a function of the various parameters, such as temperature and applied stresses and strains. Tests were performed to measure the dynamic Young's modulus and damping characteristics of various Smas using the Dynamical Mechanical Analysis (DMA) method. The experimental results show that the curve of the dynamic Young's modulus exhibits a trough shape, while the damping curve has a maximum peak during the martensite = austenite transformation. The variation of the electrical resistance of the SMAS was also measured during the phase transformation under the action of an applied stress. The results show that the applied stress plays a significant role on the electrical resistance, which not only affects its value, but also changes the phase transformation sequence. Furthermore, the effect of the strain on the electrical resistance of the SMA at different phase states (martensite, austenite, and stress induced martensite transformation) was observed. In the initial stage of deformation,, the electrical resistivity decreases as the strain increases, and demonstrates a unique functional relationship.
Investigation of Prestressed Concrete Frame Behavior with Neural Networks
Authors: Mo Y. L. , Han R. H.
Published: August 2009

To date, concrete structure modeling has involved the development of mathematical models of concrete structure behavior derived from human observation of, and reasoning with, experimental data. An alternative, discussed in this paper, is to use a computation and knowledge representation paradigm, called neural networks, developed by researchers in connectionism (a subfield of artificial intelligence) to model concrete structure behavior. The main benefits in using a neural-network approach are that all behavior can be represented within a unified environment of a neural network and that the network is built directly from experimental data using the self-organizing capabilities of the neural network, i.e., the network is presented with the experimental data and learns the relationships between stresses and strains. Such a modeling strategy has important implications for modeling the behavior of modern, complex concrete structures. In this paper, the behavior of prestressed concrete frames is modeled with a backpropagation neural network. The preliminary results of using networks to model concrete structure look very promising.
A Coupled Electromechanical Model of an Imperfect Piezoelectric Vibrating Cylinder Gyroscope
Authors: Loveday Philip W.
Published: August 2009

Coupled electromechanical equations of motion, describing the dynamics of a vibrating cylinder gyroscope, are derived using Hamilton's principle and the Rayleigh-Ritz method. The vibrating cylinder gyroscope comprises a thin walled steel cylinder which is closed at one end with discrete piezoceramic actuation and sensing elements bonded close to the open end. The operation of the gyroscope and the effect of imperfections are briefly described. The model allows direct comparison with experimental measurements in the form of electrical frequency response functions. The effects of ceramic location errors and mass imperfections were investigated. Comparisons with experimental measurements showed that the model could be used to predict the mass modifications required to reduce the effect of these typical imperfections in practical devices.
Deformation of Shape Memory Alloys Due to Thermo-Induced Transformation
Authors: Brinson L. C. , Bekker A. , Hwang S.
Published: August 2009

In this paper, a macro-scale, phenomenological constitutive model for shape memory alloys is used in conjunction with energy balance equations to study the evolution of temperature and deformation profiles seen in SMA wires under specific thermal and mechanical boundary conditions. The general, fully coupled thermo-mechanical problem is formulated and analytical solutions are determined for the decoupled case and limit cases. Results for two specific initial/boundarv value problems are presented here: 1) resistive heating of an SMA wire-initial detwinned martensite leads to strain recovery (contraction) on heating; 2) deformation wave in a semiinfinite, initially austenitic SMA wire cooled at the boundary-deformation zone propagates and expands as the wire transforms to martensite (expansion). In both cases, the region and extent of transformation is identified, indicating the magnitude of actuation obtained. Implications of the modeling for the active control of structures are discussed.
Magnetorheological Fluids: Materials, Characterization, and Devices
Authors: Ashour Osama , Rogers Craig A. , Kordonsky William
Published: August 2009

Magnetorheological (MR) fluids consist of stable suspensions of magnetic particles in a carrying fluid. Magnetorheological effect is one of the direct influences on the mechanical properties of a fluid. It represents a reversible increase, due to an external magnetic field of effective viscosity. MR fluids and devices have the potential to revolutionize the design of hydraulic systems, actuators, valves, active shock and vibration dampers, and other components used in mechanical systems. At present, there is a compelling need to develop new and improved MR fluids, to lower their production cost through improved manufacturing processes, and to develop MR fluid-based application devices that will demonstrate the engineering feasibility of the MR fluids concept and will highlight the implementation challenges. To this end, the present study is undertaken.

A unique high-speed bead mill machine, especially designed to the manufacture of MR fluids, is used to fabricate MR fluids in a laboratory-scale MR fluid fabrication facility at the Center for Intelligent Material Systems and Structures (CIMSS) at VA Tech. Characterization studies are conducted to optimize the quality and the properties of MR fluids, and different ingredients and formulations are tested to produce MR fluids that meet most appropriately the design specifications. A modified HAAKE cone-plate viscometer is used to measure the basic properties of the manufactured MR fluids. As a demonstration of MR fluid-based devices, a cross-stepper exercise machine is modified to incorporate an MR throttle valve, which is the most important element of any MR fluid system.
Model of Magnetorheological Finishing
Authors: Kordonski William , Jacobs Stephen
Published: August 2009

The technology of finishing for optics, ceramics, and semiconductors is one of the most promising uses of the magnetorheological effect. It perfectly coupled with computer control, allowing in quantity production the unique accuracy and quality of a polished surface to be achieved. The polishing process may appear as follows. A part rotating on the spindle is brought into contact with a magnetorheological polishing (MRP) fluid which is set in motion by the moving wall. In the region where the part and the MRP fluid are brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing process comes to the program-simulated movement of the polishing spot over the part surface. The mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. The problem like the hydrodynamic theory of lubrication is treated for plastic film. As this takes place, the shear stresses distribution in the film is obtained from the experimental measurements of the pressure distribution in the contact spot. Reasonable correlation between calculated and experimental magnitudes of the material removal rate for glass polishing lends support to the validity of the approach.
The Effect of Strain Rate on Detwinning and Superelastic Behavior of Ni Ti Shape Memory Alloys
Authors: Wu K. , Yang F. , Pu Z. , Shi J.
Published: August 2009

The effect of strain rate on the superelastic and detwinning behavior of shape memory alloys was studied in a series of experiments. The strain rate was tested in a range from 10-4 to 10-2/s. To ensure a stable and uniform temperature throughout the testing process, fine wire samples were used, and all tests were conducted in a liquid environment. Under these conditions, test results showed that the strain rate had no influence on the superelastic behavior and martensite detwinning of the Ni Ti alloys. In the superelastic deformation process, the austenite martensite transformation produced rather high latent heat as part of the transformation process within the specimen. As the strain rate increased, and as conditions became more adiabatic, a significant temperature change due to the release and absorption of latent heat occurred. The temperature rises upon loading and drops upon unloading. This phenomenon manifests itself, as the diameter of the specimens becomes progressively larger, or as test conditions become more adiabatic.
An Accurate Prediction of Specific Damping Capacity of TiNi SMA Composite through a Three-Dimensional Constitutive Model
Authors: Baburaj Vijayan , Kawai Masamichi , Kinoshita Katsuyuki , Koga Tatsuzo
Published: August 2009

Analytical predictions of the constitutive relations and the damping capacity of TiNi shape memory alloy (SMA) fiber reinforced composite lamina have been presented in this work. The stress induced martensitic (M-phase) and rhombohedral (R-phase) phase transformations of the TiNi SMA fiber are taken into account in the formulation of a multiaxial constitutive model of SMA material. The constitutive relation and the damping capacity corresponding to all the six directions (normal and shear) of the lamina level SMA composite have been derived based on a simple square fiber packing. The predictive capability of the present method is demonstrated by simulating the stress-strain curves under isothermal loading and unloading conditions. The specific damping capacity defined as the ratio of the hysteresis type energy dissipation to the stored strain energy is also numerically computed and furnished.
Nonlinear Hysteresis Compensation of Piezoelectric Ceramic Actuators
Authors: Chonan Seiji , Jiang Zhongwei , Yamamoto Takashi
Published: August 2009

The piezoelectric ceramic actuator generates a small displacement but a large force as well as a fast time response. Accordingly, they are commonly incorporated in the design of micropositioning xy-tables, ultrasonic motors and impact printer heads. Piezoelectric ceramics are ferroelectric, and they are fundamentally nonlinear in their response and show a significant hysteretic loop to the applied voltage signal, which sometimes causes a serious problem in their application as a linear actuator. This paper presents a study on the linear drive of nonlinear piezoelectric ceramic actuators. The experimental results show that the expansion of ceramic actuator can approximately be represented by a third-order polynomial of the applied voltage. Moreover, the hysteretic loop is significantly reduced if the input voltage to the actuator is provided again in the form of a third-order polynomial. The proposed linear drive method is first investigated theoretically. Then, a simple nonlinear preamplifier is assembled based on the proposed scheme. An experimental study is conducted to see the effectiveness of the amplifier. It is shown that the hysteretic loop on the actuator displacement disappears when the pre-amplifier is installed between the voltage generator and the DC amplifier.
Similitude Analyses for Piezostructures
Authors: Saunders William R. , Cole Daniel G. , Fannin Christopher A.
Published: August 2009

One important aspect of adaptive structure design for commercial, industrial, and defense applications is analysis of in situ active material sensitivities after integration with the host structure. In this paper, a similitude modeling approach is illustrated which can be used to normalize wide ranges of actuator and sensor properties that occur for piezostructures of arbitrary geometry and host structure materials. Nondimensional analysis techniques are applied to simple adaptive systems, comprised of piezoceramic elements surface-bonded to cantilever beams. A theoretical development shows that the electromechanical coupling (EMC) matrix scales as the characteristic length while the piezoelectric actuator force scales as the square of the characteristic length. Quasi-similar system analysis methods are introduced in order to scale piezostructures without requiring increases in element thicknesses. Numerical results are presented for the similar and quasi-similar system analyses.
Debond Detection Using Broad-Band High-Frequency Excitation and Non-Contacting Laser Vibrometer System
Authors: Lalande Frederic , Chaudhry Zaffir , Sun Fan-Ping , Rogers Craig A.
Published: August 2009

A membrane vibration-based method of detecting a debond between a host structure and a composite repair patch is presented. The two distinguishing features of this new method are the excitation and the measurement. The excitation uses a non-instrusive surface-mounted piezoceramic patch and a broad-band high-frequency multi-sine sweep. The measurement uses a noncontacting laser vibrometer and converts the broad-band excitation response into a single value equal to the RMS value of the velocity. The frequency band is selected such that the local membrane vibration of the debonded area is excited, resulting in relatively higher velocity in the debond area. The work is principally experimental with a theoretical justification of the membrane resonance detection technique. Two case studies of glass/epoxy repair patches bonded to aluminum plates with corner and edge debonds, respectively, are presented. In this work, it is shown that accurate detection of composite repair patch debonds is achievable.
Vibration Control for Precision Manufacturing Using Piezoelectric Actuators
Authors: Martinez David R. , Hinnerichs Terry D. , Redmond James M.
Published: August 2009

Piezoelectric actuators provide high frequency, force and stiffness capabilities along with reasonable stroke limits, all of which can be used to increase performance levels in precision manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self-excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in precision manufacturing.
Evaluation of Active Damping Performances in Orbit
Authors: Bousquet P. W. , Guay P. , Mercier F.
Published: August 2009

The efforts dedicated to predicting and overcoming the vibrations of structures in space have increased dramatically over the last ten years. Motivating factors behind this increase are optical systems with high stability requirements, large antennas, sensitive microgravity payloads and compatibility of flexible appendages with attitude control. Prediction activities combine analytical model and ground tests to simulate the behaviour of structures. The requirements on structural dynamic transmissions often lead to specific developments in conception such as frequency decoupling with noise sources in the spacecraft, adding passive or active damping in the structural path, or setting up suspension devices.

This paper focuses on the active damping involved in a truss structure which will be tested in the MIR station in 1996 within the frame of the CNES experiment CASTOR. This experiment aims at validating the analysis and test procedure for advanced space structure dynamic prediction, and demonstrating in zero gravity conditions the efficiency of passive and active damping technologies. After introducing the context, the paper is organised as follows:

* objectives of CASTOR

* design and optimisation of active damping system

* test results

* flight hardware and test plan

* conclusion, further activities
Active Shape Control of a Deployable Space Antenna Reflector
Authors: Tabata Masaki , Natori M. C.
Published: August 2009

Feasibility of active shape formation or correction of a deployable space antenna reflector under the conditions of limited number of actuators and limited information of its surface shape is investigated to aim to suppress its deformations mainly due to thermal loads. Those conditions are practical for actual development of large space antennas. A reflector surface control scheme through checking electrical radiation patterns, instead of measuring structural surface, is also proposed, and its performance is evaluated through numerical simulations.
Vibration Isolation, Suppression and Steering (VISS)
Authors: Wada Ben K. , Rahman Zahidul , Kedikian Roland , Kuo C. -P.
Published: August 2009

The opportunities for precision space instruments will increase if they can be accommodated on a non-precise spacecraft or platform. In order to meet the precision requirements of various space instruments, the objective was to develop a six degree of freedom Vibration Isolation, Suppression and Steering (VISS) subsystem that interfaces the instrument to the spacecraft or platform. This paper results from a study to design a flight experiment to validate the VISS subsystem for a Mid-Wave Infra Red (MWIR) Camera on top of a small spacecraft. One of the major challenges is to develop a long stroke PZT actuator that is redundant and compact, with low stiffness and power efficiency. The test performance of the actuator design and the predicted VISS performance of the design is included.
Chemomechanical Gels for Actuator System Controlled by Electrochemical Reaction
Authors: Shinohara Shinobu , Tajima Nobuyoshi , Yanagisawa Kazuhisa
Published: August 2009

We aim to make an actuator that uses the osmotic pressure of chemomechanical gels and is controlled by electrochemical reaction. This paper presents the preparation of the gels and measurement of pH change and gel actuation by the electrochemical reaction. Finally, we suggest one example of application suitable for gel actuator.

The gels are made by photo-polymerization with ultraviolet irradiation to vinyl-monomers which are N,N'-dimethyl aminopropyl acrolamide (DMAPAA), Methylene-bis-acrylamide (MBAAM). Poly-vinyl alcohol (PVA) is added to the monomer solution to make the gels elastic. Swelling ratio and Young's modulus of the gels were measured in electrolyte solution with deferent pH and ion concentration. It became clear that the Young 's modulus of the gels increased with increasing the swelling ratio which was proportional to the osmotic pressure. This result is suitable for the actuator which uses the swelling pressure of the gels.

The oxidizing and reducing agent for the electrochemical reaction is Ethyl Viologen Dibromide. The cell with the working electrode is separated from the cell with the counter one by an ion exchange membrane. The oxidation by applied potential of + 1.0 V decreases pH from 12 to 4 within 3 minutes. In the case of reduction, the potential of -0.8 V increases pH for 4 to 12 within the same minutes.

The change of pH swells or shrinks the chemomechanical gels similar to adding acid or alkaline to the solution. Without stirring, it is difficult that pH change spreads into the gel completely in the short time, which causes the hysteresis. As the application of the gel actuator, a continuous dispenser is suggested and confirmed to discharge liquid from the balloon.
Humidity-Induced Volume-Expansion of Polyimide Films
Authors: Sager Karsten , Schroth Andreas , Gerlach Gerald
Published: August 2009

Thin polyimide layers were investigated to determine their volume expansion as a result of humidity absorption and desorption, respectively. Furthermore, we used the experiments in order to clarify the physical and chemical processes of polyimide films in wet environment as well as their humido-mechanical properties. It could be shown that the humidity-induced material extension is fairly linear in a wide range of humidity. The observed material behaviour strongly depends on the conditions of the polyimide fabrication process. Analogous to the well-known temperature extension coefficient, a humidity extension value of about 60 to 90 ppm/%RH was observed. This physical effect can be used to create piezoresistive humidity sensors working similarly to bimetal elements influenced by temperature.
Vibration Suppression Effect of Liquid Crystal under Electromagnetic Field
Authors: Tani Junji , Takagi Toshiyuki , Nakaniwa Hirofumi , Ohtomo Kikuo , Kosugo Kazuo
Published: August 2009

This paper describes an experimental study on the vibration suppression of a laminated beam with a nematic liquid crystal under electric and magnetic fields. Firstly, a laminated beam is constructed with two thin nematic liquid crystal layers and a thin aluminum beam inside. The results under electric field show that the resonance point of the beam shifts higher, and the response displacement amplitude decreases as electric field strength increases. This is because the apparent viscosity of a liquid crystal and the stiffness of the beam change when electric field is applied. Considering these results, this laminated beam is modeled as a spring-mass-damper model and a simulation is performed based on this model. The experimental and simulation results almost agreed. Then the effect of magnetic field is investigated experimentally. The damping effect appears in high magnetic field, but this effect might be caused by magnetic damping effect due to induced current and not by the damping effect of the liquid crystal.
Vibration Suppression of a Cylindrical Shell Using a Hybrid Control Method
Authors: Qiu Jinhao , Tani Junji
Published: August 2009

The forced vibration of a cylindrical shell is controlled using the distributed piezoelectric actuators and hybrid control method. The shell is constructed from a polyester film in the middle surface and two piezoelectric films, one on each side. The electrodes on the surfaces of the piezoelectric films are divided into several parts, and two parts of the films are used as actuators. The shell is vertically mounted on a vibration table and excited by the horizontal motion of the table. The hybrid control method which is a combination of it-synthesis control and disturbance cancellation method is used. Simulation and experiment were carried out and the results show that the hybrid control is more effective than each individual control method.
Force Control of a Flexible Finger with Distributed Sensors and Piezoelectric Actuators
Authors: Tanaka M. , Chonan S. , Jiang Z. W.
Published: August 2009

This paper is concerned with the theoretical and experimental study of the force control of a miniature robotic finger that grasps an object at portions other than the fingertip. The artificial finger is a uniform flexible cantilever equipped with a distributed set of compact grasping force sensors. Control action is applied by a piezoceramic bimorph strip place at the base of the finger. The mathematical model of the assembled electromechanical system is developed. The distributed sensors are described by a set of concentrated mass-spring systems. The formulated equations of motion are applied to the study of control problem where the finger is commanded to grasp its object with a time-constant force 0.03 N regardless of the contact position of the finger with the object. Both the PID and H0, regulators are tested and their control behaviours are compared with each other.
Health Monitoring of a Continuous Fiber Reinforced Aluminum Composite with Embedded Optical Fiber
Authors: Asanuma Hiroshi , Ichikawa Kentarou , Kishi Takehiro
Published: August 2009

The possibility of health monitoring of a continuous fiber reinforced aluminum composite with embedded optical fiber was demonstrated in this paper. Though quartz type optical fiber can be very damaging, it could be successfully embedded in a continuous fiber reinforced aluminum composite by the interphase forming/bonding method. The composite was bent or wear tested under monitoring of optical loss through the embedded optical fiber. In the case of bending, the optical transmission loss apparently increased when reinforcement fiber fractured by tension or compression. In the case of wear test, loss of reflected light from the sliding plane increased by roughening it. These results show that the embedded optical fiber can work as a health monitor of characteristic properties of the continuous fiber reinforced aluminum composite.
Alloys Design of PdTi-Based Shape Memory Alloys Based on Defect Structures and Site Preference of Ternary Elements
Authors: Hosoda Hideki , Enami Kazuyuki , Kamio Akihiko , Inoue Kanryu
Published: August 2009

Defect structures and site preference of ternary elements in B2-type PdTi alloys are evaluated in order to design PdTi-based smart materials using the pseudo-ground state analysis (or analysis performed at near zero Kelvin). It has been found that this analysis can predict types of defect structures in these alloys which are of antistructure (substitution) type regardless of alloy compositions. Substitution behavior predicted is as follows: (1) most elements belonging to groups 1A through 5A occupy Ti sites only; (2) most elements belonging to groups 6A through 8A occupy Pd sites only; and (3) the others studied occupy either sites when these sites are unfilled with the corresponding constituent elements (Pd or Ti). Moreover, effects of both offstoichiometry and 3dtransition elemental additions on martensitic transformation start temperature (MS) in PdTi alloys are evaluated as a function of electron-atom ratio (e/a). It has been found that M, is strongly related to the e/a value when 3d electrons of ternary additions are taken into account, although the effect of e/a on M, differs if their substitution behavior is different. Changes in M, per e/a are estimated to be 900 K when Pd-site substitution elements, such as Cr, Mn, Fe, Co, and Ni are added, while changes in M, per e/a are 790 K when Ti-site substitution elements such as V are added. This suggests that M, is influenced not only by the e/a value but also by atomic configurations.
Design and Material Evaluation of Shape Memory Composites
Authors: Furuya Yasubumi
Published: August 2009

Shape memory alloy (SMA) is regarded as one promising intelligent material element natively with thermo-sensor, shape memory actuator functions. A fundamental design concept for intelligent materials using SMAS is firstly proposed. Two types of composites which show some intelligent functional properties relating to the shape memory phase transformation were fabricated. One is the shape memory TiNi fiber/Al matrix plate. Another is the plaster matrix composite as a model of building material which contains both shape memory TiNi fibers and high damping TiNi particles having different phase transformation temperatures with each other.

The former (TiNi)f/Al composite showed unique properties such as self-strengthening by the compressive stresses in Al matrix due to shape memory shrinkages of the embedded TiNi fibers. The increases of tensile property (yield stress) as well as fatigue resistance (crack growth retardation) at higher temperature were experimentally confirmed. The latter (TiNi),f/plaster showed the increases of resistance to fracture as well as vibration damping.
Multi-Freedom Tube Type Manipulator with SMA Plate
Authors: Kaneko Shinji , Aramaki Shinji , Arai Kazuhiko , Takahashi Yuichiro , Adachi Hideyuki , Yanagisawa Kazuhisa
Published: August 2009

The tube type multiple link micromanipulator using SMA (Shape Memory Alloy) has been conducted. The conceptual model of this manipulator has five linked pipes with 1 mm in diameter. On each link, a temperature/strain sensor and a control IC chip are equipped for position and/or force feedback control. We have successfully fabricated a prototype. This tube type manipulator, which is 2 mm in diameter, has two links.

This prototype manipulator has two flexible SMA plate links which are given all direction shape memory effect over 60 degrees in vending angle. These links mutually bend at a right-angle. These SMA plates are fixed SUS pipes through which a silicon rubber tube is arranged. By using the technology of semiconductor manufacturing, the MIF (Multifunction Integrated Film) has been developed for integration of electrical elements for the manipulator. The MIF has several functions; strain sensor, temperature sensor, heater, and wires to interconnect links. In this manipulator, the MIF with 7 itm in thickness is attached to each SMA plate.

As a flip-flop circuit chip is mounted on each MIF in a state of bare chip, many heaters and sensors are controlled serially by shift-resisters. Therefore, this manipulator is controlled by eleven common wires even if the number of links increases.

The heater is constructed with Ti film. The sensors are constructed with Ti film and Pt film. As these two materials have different gage factors and temperature coefficients, the value of temperature and strain can be calculated from the change of the resistivity.

By PID feedback control with strain and temperature, the positioning error at the end of the link is less than 0.2 mm.
Development of Real-Time Microvision System Based on Three-Dimensional LSI Technology
Authors: Yu Kee-Ho , Kudoh Yoshihara , Matsumoto Takuji , Pidin Sergey , Koyanagi Mitsumasa
Published: August 2009

The development of the real-time microvision system with three-dimensional (3D) structure is introduced. A number of two-dimensional LSIS (2D-LSIs) which play amplifying and converting image signal and some arithmetic operations are fabricated vertically. The microvision system transfers the two-dimensional (2D) image data arrays as it is using high density vertical interconnections. The image information signals are processed in parallel in each LSI and the processing is performed in pipeline over all the system. In fabrication, grinding and chemical-mechanical polishing techniques are used to thin the wafer to 30 ym. The thinned wafer with buried interconnections is bonded vertically to a thick wafer through microbumps after careful alignment by the wafer aligner with the alignment tolerance of 1 Mm. The real-time microvision system with 3D structure can be fabricated by repeating such sequence.
Smart Materials: A Future for Composites
Authors: Gobin P -F. , Gutnin G. , Morin M. , Salvia M. , Tatibouet J.
Published: August 2009

Obviously, successive expertises in the processes of elementary materials are milestones which marked the early stages of mankind development (stone-age, bronze-age,...) and it is only since the beginning of the century that materials became multifunctional and required optimization of their different physical, mechanical, and/or chemical properties. The evolution is going on toward the concept and the process of composite or heterogeneous materials where somewhat opposite properties are often associated. Nowadays, another step is going to be done by introducing the concept of "intelligence". Different aspects of the concepts for intelligent composite materials (sensitive, adaptable, and adaptive materials) are discussed and illustrated through some realisations or projects which are developed in this promising field of interest.
Limits of Stress Reduction in a Plate with a Hole Using Piezoelectric Actuators
Authors: Sensharma Pradeep K. , Haftka Raphael T.
Published: August 2009

Recently there has been much interest in adaptive structures that can respond to a varying environment by changing their properties. Shape memory alloys and piezoelectric materials can be used as induced strain actuators to reduce stresses in regions of stress concentration. In a previous work, we have shown that stress concentration in a plate with a hole can be reduced substantially by applied induced strain. However, limited free induced strain (1000 JAE) and low tensile strength limit the effectiveness of piezoceramics for active stress alleviation. Also, bonded actuators increase the weight of the structure and may have shear lag effects. The present work determines the effects of such limitations on stress reduction for two load cases: a fatigue load case and an extreme load case. Piezoelectric actuators were found to be ineffective in reducing stress concentration factor for the extreme load case. For the fatigue load case, effectiveness depends on the cost and weight associated with supplying actuation energy.
A Consistent Theory of Thin Piezoelectric Plates
Authors: Bisegna Paolo , Maceri Franco
Published: August 2009

In this paper a theory of thin piezoelectric plates is obtained throigh a rational derivation from the three-dimensional linear theory of piezoelectricity. The coupling between the ekictric and mechanical fields is taken into account, leading to a consistent definition of the bending and stretching stiffnesses. In particular, it is shown that a piezoelectric plate has a different stretching stiffness when it is used as an actuator or as a sensor.

The procedure used to derive the field equations governing the piezoelectric plate problem is based on the initial functions method, in conjunction with a rescaling of the applied loads. The field equations are then rewritten in a variational form, according to a generalized statement of the virtual work principle, in order to deduce the compatible boundary conditions.

The theory established here is used to find closed-form expressions of the solutions of some technical problems, involving piezoelectric plates used as sensors or actuators.
Dynamics of a Mechanical System with a Shape Memory Alloy Bar
Authors: Feng Z. C. , Li D. Z.
Published: August 2009

We study the dynamics of a simple mechanical system containing a mass and a bar made of shape memory alloys. Our objective is to understand the effect of stress induced phase transtormation on the system dynamics. Specifically, the effectiveness of an idealized vibration isolator made of shape memory alloys is examined both numerically and experimentally. We find that the stress induced phase transformation within the material has two effects: the resonance frequency of the system is lower and the peak response near the resonance is heavily suppressed. Furthermore, both of these effects depend on the forcing amplitude and they are more pronounced at large forcing amplitudes. We also find that nonlinearity associated with the phase transformation gives rise to complicated dynamics. In particular, period-three responses are found for some forcing parameters. It the case of a biased load, period-doubling cascade and chaotic motion can occur. However, this complicated dynamics disappears at large forcing amplitudes, making the shape memory alloy vibration isolator an effective device at large forcing amplitudes.