The synthesis and characterization of photoactive monolayers is described. Monolayers containing azobenzene were prepared either by direct chemisorption of a trichlorosilane or by covalent attachment to a functionalized self-assembled monolayer (SAM). Preliminary photoisomerization studies show a decrease in wettability upon exposure to ultraviolet light. In addition, a new experimental methodology for measuring protein adsorption to SAMs was developed. Neutron reflectometry measurements show that the protein, Human Serum Albumin (HSA), adsorbs onto both methyl- and ammonium-terminated SAMs. However, more protein was found in the interphase next to the methyl-terminated SAM.

We describe a methodology for immobilizing the enzyme alkaline phosphatase onto a glass surface using a novel biotinylated copolymer poly (3-undecylthiophene-co-3- thiophenecarboxaldehyde) 6-biotinamido hexanohydrazide attached hydrophobically to silanized glass. The biotin-streptavidin protein interaction is used to carry out this immobilization. Alkaline phosphatase catalyzes the dephosphorylation of a class of macrocyclic compounds: including CSPD {chloro 3-[4-methoxy spiro(1,2 dioxetane-3-2-trichloro-(3.3.1.1)-decan]-4 yl}phenyl phosphate to a product species which emits energy by chemiluminescence. We can detect this chemiluminescence signal with a photomultiplier tube for both enzymatic catalysis in solution and the surface immobilized enzyme (streptavidin conjugate). This enzyme is inhibited by the organophosphorus class of pesticides as well as nerve agents. The enzyme is also inhibited by Be(II), Bi(III) as well as excess Zn(II), while the apoenzyme is reactivated by Zn(II). We demonstrate in this study that two representative organophosphorus pesticides inhibit the enzymatic production of chemiluminescent products. This is true for the enzyme conjugate both free in solution and immobilized. We can detect pesticides down to about 50 ppb for the enzyme in solution and 500 ppb for surface immobilized enzyme in a 100 (mu) l capillary. Detection of Zn(II) by apoenzyme reactivation occurs down to 3 ppb. Be(II) and Bi(III) are detected by inhibition down to 1 ppm.

The preparation and properties of four classes of functional polymeric materials capable of responding to changes in the environment are reported. The microphase separated mixed (ionic and electronic) or MIEC diblock copolymers are composed of an electronic conductive and an ionic conductive block, and are nanostructured smart materials for application in MEMS devices. Processable copolymers of 3-alkyl or 3-phenylthiophene and (3- oligodimethylsiloxane)thiophene have been prepared as electrorheological fluids. Also a facile methodology for preparing highly ionic conductive and elastomeric solid electrolytes is reported. Finally, molecular composites of poly(2-vinylpyridine) and lithium perchlorate have been prepared. These composites have dielectric constants as high as 16 at 12 GHz.

Using the method of cyclic voltammetry a number of well known electron mediators have been investigated on a teflon coated platinum wire, the tip of which has been modified by a self-assembled bilayer lipid membrane (s-BLM). Electrical capacitance of the s-BLM system was measured as a function of the frequency. The findings of this work are discussed in terms of the electron transfer phenomena and the redox reactions.

Reported are a number of quantitative observations and analytical modeling of a new effect in ionic polymeric gels such as poly(2-acrylamido-2-methylpropanesulfonic acid) or PAMPS, polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM), or various chemically doped combinations of polyacrylic acid plus polyvinyl alcohol (PAA-PVA). This new effect, hereafter, referred to as `flexogelectric effect' is basically the inverse of the effect originally reported in 1965 by three GE researchers, namely, Hamlen, Kent, and Shafer in which the imposition of an electric field on an ionic polymeric gel fiber produced extension or contraction. Here it is shown, both theoretically and experimentally, that mechanically induced nonhomogeneous deformations, and in particular bending of strips of such ionic gels, can produce an electric field and the associated voltage. For typical samples of such gels (4 X 4 X 40 mm) with copper or platinum foil electrodes snugly contacting a pair of opposite sides (4 X 40 mm) of the strip, the difference in voltage measured between the electrodes for extreme bending configurations of the gel is typically in the 10s of millivolts range. This voltage difference which is quite significant for many engineering applications, such as large strain and deformation sensing, is still an order of magnitude smaller than the voltage necessary to induce similar deformations in the gel itself. A plausible explanation is also presented for such discrepancies.

A new class of intelligent materials is introduced. These chemtronic materials are able to save information on their dynamic surfaces. Then, the information can later be retrieved from the surface. Conducting polypyrrole and polyaniline are used to show such capability in sensing technology. Resistance of the polymer was found to be pH dependent. Therefore, these materials are then recommended as chemtronic materials with potential of being used as pH sensors.

Amino-acid modified diacetylenes were used as organic templates for controlled biomineralization. Macromolecular changes in the monolayers have been observed upon application of pressure or polymerization. The degree of film compression and film polymerization influenced calcium carbonate polymorph selectivity. The desired optimization of the physical properties of the biomineral product is approached via structural control of the organic monolayer.

A new type of very low stiffness super-active composite material is presented. This laminate uses shape-memory alloy (SMA) filaments which are embedded within a low Durometer silicone matrix. The purpose is to develop an active composite in which the local strains within the SMA actuator material will be approximately 1% while the laminate strains will be at least an order of magnitude larger. This type of laminate will be useful for biomimetic, biomedical, surgical and prosthetic applications in which the very high actuator strength of conventional SMA filaments is too great for biological tissues. A modified form of moment and force-balance analysis is used to model the performance of the super-active shape-memory alloy composite (SASMAC). The analytical models are used to predict the performance of a SASMAC pull-pull actuator which uses 10 mil diameter Tinel alloy K actuators embedded in a 0.10' thick, 25 Durometer silicon matrix. The results of testing demonstrate that the laminate is capable of straining up to 10% with theory and experiment in good agreement. Fatigue testing was conducted on the actuator for 1,000 cycles. Because the local strains within the SMA were kept to less than 1%, the element showed no degradation in performance.

The thermomechanical response of shape memory alloy (SMA) materials under cyclic loading is modeled in this paper. A set of evolution laws for plastic strains is first developed, based on Bodner's viscoplasticity model, by replacing real time in Bodner's model with an internal time variable proportional to the martensitic volume fraction. The influence of plastic residual stresses on the martensitic phase transformation is analyzed, and evolution equations for the plastic back stresses and isotropic hardening parameter during phase transformation are developed. The relationship between accumulation of plastic strains and creation of the two way shape memory effect is quantitatively explained by the present model. The changing of the stress-strain hysteresis loop and transformation start and finish stresses and temperatures are also correctly accounted by the present formulation.

Shape memory alloys are an example of active materials which are used as sensor-actuator materials. Their performance is related to a (thermoelastic) martensitic transformation. At present, new compositions other than the already industrial, Ni-Ti and Cu-Zn-Al, are being developed for higher temperature applications (370 to 470 K). Among them, the Cu-Al-Ni system, with the addition of other elements to improve its mechanical properties, is being explored. For this alloy the martensitic transformation takes place between a high temperature cubic structure, (beta) -phase, and a low temperature structure with lower symmetry, the martensite phase. The addition of Ti produces the precipitation of second phase particles, (Cu,Ni)₂AlTi, which have a structure and lattice parameter close to the one of the (beta) -phase. The presence of the second phase substantially modifies the elastic modulus and damping characteristic of the phases involved in the martensitic transformation. Especially important is the modification of the E-modulus values of respectively the martensite and (beta) -phase below and above the transformation temperatures: for a precipitate-free material their values are similar whereas the presence of precipitates produce an important increase in the (beta) -phase modulus value which nearly doubles that of the martensite. In the present communication this behavior is described as a function of the precipitate size distribution and coherency degree with the matrix. Some insight of the microstructural mechanisms leading to this behavior are discussed. This large modulus change could be applied in active modal modification techniques.

The mechanical properties of Ni₅₀Ti₅₀ deposited on Si substrates were studied focussing on the interaction of the film and substrate. This interaction determines the transformation characteristics through interface accommodation and mechanical constraints exerted by the substrate stiffness. Substrate stiffness, controlled by the film/substrate thickness ratio, was found to have a substantial influence on the output energy of the film/substrate composite. A switch type composite based on this knowledge was fabricated and tested. The thermo-mechanical properties of Terfenol-D thin films deposited on Si substrates were studied by static and dynamic measurements of film/substrate composite cantilevers. The Curie transition, (Delta) E effect and mechanical damping of the film were measured simultaneously. The stress in the film was controlled by annealing below the recrystallization temperature and determined to vary from -500 MPa, compression, in as deposited films to +480 MPa, tension, in annealed films. The Curie temperature shifts from 80 degree(s)C to 140 degree(s)C as the tension increases while the structure of the film remains amorphous. The stress change induced by annealing also drastically effects the film's damping characteristics. The (Delta) E effect of the amorphous material, about 20%, was used to estimate the magnetostriction, (lambda) _s approximately equals 4 (DOT) 10^-3.

This paper focuses on the study of damping behavior associated with the R-phase in NiTi shape memory alloy. The variation of the tan((delta) ) and Young's modulus as a function of temperature, ramp rate, frequency, and applied amplitude are systematically studied using a dynamic mechanical analyzer (DMA). It was found that the tan((delta) ) versus the temperature curve exhibits four peaks during the thermal cycle, two peaks each in the heating and in the cooling process. These peaks correspond to the martensite to R-phase, R-phase to austenite, austenite to R-phase, and R-phase to martensite transformations. The value of the tan((delta) ) at each peak is in proportion to the ramp rate and in reverse proportion to frequency. The vibration amplitude tends to have a minor effect on the tan((delta) ). The variation of these peaks with ramp rate, frequency, and amplitude are discussed based on the Delorme and De Jonghe damping model. In addition, the experimental results show that an isotropic softening occurs in the Young's modulus during martensite to R-phase, R-phase to austenite, austenite to R-phase, and R-phase to martensite transformations.

The stability of the shape memory effect associated with both the R-phase and martensitic transformations was investigated in Ti-Ni sputter-deposited thin films. The R-phase transformation characteristics showed perfect stability against cyclic deformation because of the small shape change which caused no slip deformation to occur, while the martensitic transformation temperatures rose and temperature hysteresis decreased during cycling because of the formation of internal stress which is due to the introduction of dislocations. However, no slip deformation occurred during cyclic deformation under 100 MPa because of small grains so that perfect stability of shape memory effect was also observed in the martensitic transformation. Besides, with increasing the number of cycles under higher stresses, the shape memory characteristics associated with the martensitic transformation were stabilized by a training effect.

Ti-Ni-Cu and Ti-Ni-Pd ternary shape memory alloy thin films were made by sputtering. They showed smaller temperature hysteresis and higher transformation temperatures, respectively, than those of Ti-Ni binary thin films; these characteristics are effective to achieve a high response actuator characteristic. The transformation temperatures and shape memory behavior were characterized by DSC measurement and thermal cycling tests under a variety of constant stresses, respectively. The Ti-Ni-Pd thin film showed a single stage transformation both upon cooling and heating similarly to a Ti-Ni binary alloy thin film which was also made in the present report; the transformation occurred between the parent B2 phase and martensite M(monoclinic)-phase. Correspondingly, they showed a single stage deformation both upon cooling and heating. The Ti-Ni-Cu thin film showed a two-stage transformation and hence a two-stage deformation; the first stage corresponds to the transformation between B2 and O(Orthorhombic)-phase and the second stage between the O- and M-phases. The first stage transformation was accompanied by a small temperature hysteresis. All these thin films showed perfect shape memory effect.

Using conventional magnetron sputtering deposition processes three different types of shape memory alloys (FeNi based, CuAl based and TiNi based) were examined as potential candidates for the production of high temperature SMA thin film. CuAlNi and TiNiHf SMA were successfully deposited on silicon wafers and thin films of 4 - 20 micrometers were produced. After annealing at approximately equals 500 degree(s)C both CuAlNi and TiNiHf films exhibited reversible high temperature martensitic transition. For CuAlNi thin films, annealing itself was found to be inadequate for obtaining transformation intervals corresponding to that of the target. To deal with the problem it is expected that additional quenching after solid solution heat treatment will be necessary. Of the three alloys examined, the most promising candidate for high temperature thin film microactuators is TiNiHf. It was found that by changing the Hf content in the target, the transformation start temperature of thin films can be easily adjusted in a temperature range from 100 degree(s)C to 200 degree(s)C.

We have recently observed photomechanical effects in polymer optical fibers (light-induced length changes) and have used these effects to build smart devices such as active vibration suppressors and light-actuated positioners. The unique feature of these devices is that they are all-optical, that is, the light is used as the actuating power source, medium of information transfer, sensing and logic. We have designed a cylindrical mesoscopic photomechanical unit (MPU) that is about 80 micrometers in diameter and less than 1 mm in length and report on a first generation miniaturized device that is 2 cm X 100 micrometers .

We report on the development of liquid crystal smart reflectors, consisting of a cholesteric liquid crystal with temperature sensitive helix pitch, in combination with a light absorbing dye. Light entering the liquid crystal is absorbed by the dye, generating heat which raises the temperature of the liquid crystal. The resulting change in the helix pitch of the cholesteric causes an increase in its reflectivity, reducing the intensity of light that can be absorbed by the dye. This negative feedback stabilizes the reflector for a given light intensity. The smart reflector thus achieves a reflectivity which increases with increasing intensity of incident light. We report on two configurations of the device, with both experimental measurements and mathematical models of the system.

This paper reports the results of our study on structure configurations and material compositions for the construction of smart photonic bandgap structures. The study focuses on the deposition of various Langmuir-Blodgett films for realizing these structures. Multilayer polymeric L-B films using different materials have been deposited and their physical properties studied using atomic force microscopy. Possible causes of film non-uniformity are investigated.

We report results from a research program that investigates the feasibility of using optical fiber sensors to experimentally verify the performance of actuator elements attached to and embedded in prototype smart material systems, as well as to determine the nonlinear behavior of the actuator material response. The measurement of strain parallel to the long-axis of extrinsic Fabry-Perot interferometric (EFPI) fiber sensors is presented for three PZT/material configurations and one PMN configuration as a function of applied actuator excitation. These arrangements simulate the performance of an actuator by itself, in a stack, embedded in a surrounding material matrix, and attached to a supporting structural material. Experimental results are presented.

In this paper, we present a nonlinear constitutive relation for magnetostrictive materials that includes coupling between temperature/preload and magnetic field strengths. The nonlinear constitutive relations are also integrated into a 1-dimensional nonlinear finite element model for studying structural components or composite materials containing magnetostrictive materials. The accuracy of the nonlinear constitutive relation is evaluated by comparing experimental results obtained on a Terfenol-D rod operating under both magnetic field and stress biases with theoretical values present in the literature. Results indicate that the model adequately predicts the nonlinear strain/field relations in specific regimes. Experimental tests, conducted on monolithic samples of different geometry, suggests that size effects may be important. A manufacturing process and preliminary experimental tests are also presented for a 1 - 3 magnetostrictive composite sample.

We present a theoretical and experimental study of large micro mechanical cantilever beams fabricated by the SCREAM (single crystal reactive ion etching and metallization) process. SCREAM beams consist of an SCS core coated by films of SiO₂ or nitride and metal. Thermal and intrinsic stresses develop in the beams due to the films and tend to deform them. Such deformations result in non-planar structures. For small micro mechanical systems, the non-planarity is negligible. When the structures' size is of the order of few millimeters, the non-planarity may limit the performance of the device. Here, we first treat the thermal and intrinsic strains of the films as material properties and measure them experimentally for PECVD SiO₂. We then develop a simple model to predict the deformation of cantilever beams due to the thermal and intrinsic strains of SiO₂ or nitride film. The model predicts that the non-planarity of the beam can be controlled by properly choosing the cross sectional dimension of the beam. We validate the theoretical prediction by fabricating cantilever beams which deform with negative, positive, and almost zero curvature.

Polymer composites with high dielectric constant are widely used as shielding and field grading materials. An improvement of the refractive grading can be expected for a dielectric constant being a nonlinear function of the electric field or the temperature, as it is known for nonlinear resistive field grading. An increase of the dielectric constant in those areas, where the highest electrical fields occur, will result in a homogenization of the field distribution. Such composite materials can be considered as having the smart functions of sensing and actuating. The influence of nonlinear properties of filler material on the resulting dielectric properties have been studied both theoretically and experimentally. Calculations using effective medium theory show how much of the non-linearity of the filler is transferred to the composite. They are compared with experiments on composites containing ferroelectric, semiconducting and varistor-type filler material in a thermoset or thermoplastic matrix. Depending on the filler type, the dielectric constant increases by a factor of up to three, for example, by raising the temperature from 30 degree(s)C to 150 degree(s)C. Such an enhancement can be sufficient to rearrange the field distribution in stressed insulating parts.

Smart materials, containing sensors, actuators and processing electronics, are of great potential use in defense and commercial applications from acoustic stealth to medial imaging. While 1:3 composites using PZT rods are now available commercially in limited quantities, composites with individually addressable actuator and sensor arrays are not, nor have conditioning and processing electronics been embedded in the same material. There are several technical and cost reasons for this, including the complexity of interconnections, capacitance of individual elements, thermal dissipation, and the expense of fabricating the material. We have been developing composite materials comprising arrays of miniature actuators fabricated using surface mount capacitor technology, and amenable to automated fabrication using `pick and place' techniques. Miniature actuators with up to 0.1% strain, and operating at 30 V bias and ac swing of +/- 30 V have been fabricated, and placed in 10-by- 10 actuator arrays on Kapton sheets on which circuits have been printed. The arrays were then `potted' in RTV liquid rubbers. Individual actuator motion and multiple actuator influence functions were measured as a function of applied voltage and adjacent actuator motion. These results, along with in-water performance (source level and directivity), are presented.

Epitaxial SrRuO₃ thin films were deposited on SrTiO₃(100) and MgO(100) substrates by rf sputtering for use as bottom electrodes and epitaxial buffer layers. On these conductive substrates, epitaxial Pb(Zr_xTi_1-x)O₃ (PZT; x equals 0.35, 0.65) and PbTiO₃ (PT; x equals 0) thin films were deposited by metalorganic chemical vapor deposition (MOCVD). X-ray diffraction (XRD), RBS channeling (RBS), transmission electron microscopy (TEM) and optical waveguiding were used to characterize the phase, microstructure, defect structure, refractive index, and film thickness of the deposited films. The PZT and PT films were epitaxial and c-axis oriented. Ninety degree domains, interfacial misfit dislocations and threading dislocations were the primary structural defects, and the films showed as high as 70% RBS channeling reduction. Ferroelectric hysteresis and dielectric measurements of epitaxial PZT ferroelectric capacitor structures formed using evaporated Ag top electrode showed: a remanent polarization of 46.2 (mu) C/cm², a coercive field of 54.9 kV/cm, a dielectric constant of 410, a bipolar resistivity of approximately 5.8 X 10⁹ (Omega) -cm at a field of 275 kV/cm, and a breakdown strength of > 400 kV/cm. Cyclic fatigue measurements showed that the remanent polarization was maintained for > 10⁹ cycles.

The electric field induced antiferroelectric-to-ferroelectric phase transition of lead zirconate titanate stannate ceramics was investigated by means of dielectric, polarization, and strain hysteresis measurements. Compositions of varying titanium and tin within the general formula (Pb_0.98La_0.02) (Zr_0.66Ti_0.11-xSn_0.23+x)O₃, located in the tetragonal antiferroelectric phase field and near the ferroelectric rhombohedral boundary were prepared. As the applied electric field increased, a sudden increase in both longitudinal and transverse strain was observed with a corresponding change in dielectric constant, loss, and polarization, indicating the transition from antiferroelectric to ferroelectric phase. The longitudinal strain increased continuously into the ferroelectric phase, whereas the transverse strain became negative after the phase change. By defining the phase change field from polarization and high field dielectric constant and loss measurements, the longitudinal strains associated with the phase change for all of the compositions were less than 0.2%. For some compositions, however, the longitudinal strain increased to levels greater than 0.5% with increasing applied field. Owing to the relatively small decrease in transverse strain in the ferroelectric region, the volume strain continued to increase even after antiferroelectric to ferroelectric phase change.

Thin film layers of shape memory alloys and ferroelectric ceramics can produce a family of smart heterostructures capable of performing both sensing and actuating functions. Important issues in the synthesis of these active structures are the ability to generate the appropriate crystalline phases of each material while producing defect-free homogeneous high-quality films. The compatibility of sol-gel-processed Pb(Zr,Ti)O₃ (PZT) thin films with thin film shape memory effect TiNi substrates were investigated Thin film TiNi was deposited on quartz substrates by physical sputter deposition utilizing a TiNi target in a ultrahigh-vacuum chamber, which was followed by in- site vacuum annealing. The ferroelectric tetragonal phase of PZT was deposited on TiNi by sol-gel and spin-coating processes followed by a 600 degree(s)C anneal for 5 m in air. The heterostructures obtained were nominally defect-free, unlike those obtained through deposition onto bulk TiNi substrates.

Vibrations are detrimental to the performance and durability of flexible structural components used in engineering systems. Structural vibrations can cause pressure perturbations in air, especially when the structural modes are well coupled with the sound field, leading to undesirable radiated noise. Methods for vibration and acoustic radiation minimization in flexible plate structures using piezoelectric materials as sensors and actuators are addressed in this paper. Development of effective compensation techniques to enable the active structure to maintain its structural reliability, requires understanding the vibrational and acoustic response characteristics of the active structure. Based on such response characteristics, a dual active control scheme is developed for vibration and acoustic radiation reduction. The dual scheme is based on a modified form of the filtered-x LMS algorithm. A fuzzy inference adaptation method is used to regulate the learning rate and control output of the LMS adaptive algorithm, depending on the levels of vibrations or noise present. Experimental results obtained from the real-time implementation of a vibration control scheme, and the dual active scheme on a typical active plate structure is presented.

Vickers indentation is a popular method for determining fracture toughness of brittle materials. Although this method depends on an empirical formula relating the stress intensity factor (or toughness) to the indentation parameters, it is simple and economical. In this study, the Vickers indentation method was used to determine the apparent fracture toughness of PZT- 4 piezoceramic under the influence of electric fields. The mechanical strain energy release rate associated with the crack produced by the Vickers indentor was derived. Using the analytical mechanical strain energy release rate for an infinite piezoelectric medium with a center crack and far field in-plane mechanical and electrical loadings, the mechanical strain energy release rate was obtained for Vickers indentation, which involves the out-of-plane indentation load. The effect of the electric field is properly included. The accuracy of the proposed formula was verified by experimental results.

Local control of an acoustic projector or boundary can, in principal, be accomplished using large area locally controlled actuators with an imbedded or intimately bonded sensor array. However, in practice the marriage of an actuator and sensor array is not straightforward. Issues of area sampling, nearfield sensing, internal resonances, and both direct and extraneous coupling mechanisms all can contribute to complicate the system transfer functions and limit the applicability of this approach. In a basic research study, this paper considers the design and performance of a generic smart actuator for underwater acoustic applications. Both surface pressure and surface velocity sensing are included. Models are presented for understanding the importance of some of the mechanisms and construction issues involved, and for predicting the resulting system transfer functions. The predictions are compared with freefield experimental results.

Realistic prediction of dynamic responses in electrorheological (ER) media demands spatially stochastic constitutive modeling. Sample random fields for yield stress functionals can be constructed for numerical simulation with finite and boundary elements on the basis of the covariance relations obtained from experimental data. This paper focuses on a computational strategy to implement such observed responses. The present formulation of the stochastic constitutive relation has been extended for two and three dimensional problems by employing the standard techniques of the invariant formulation generic to mathematical theory of continuum mechanics. Symbolic computer programs are emphasized along with numerical codes for critical evaluation of the proposed finite/boundary element schemes.

The issue of precision position control is critical if piezoelectric actuator technology is to be applied in increasingly demanding applications. In one particular application, the NASA NAOMI project, piezoelectric actuators have been proposed as the pointing and focusing elements for thousands of small mirror-lenslets because of their fast response time and load- carrying ability. In this application the positions of these actuators must be precisely controlled both statically and dynamically to the nanometer level. This requirement necessitates a careful study of the concept and design of the driving electronics of the system. This paper is focused on finding an appropriate method for driving piezoelectric stack actuators for ultraprecision position and motion control. In this paper the theoretical basis of the electrical control of piezoelectric stack actuators is derived using the fundamental physical laws governing dielectrics and piezoceramics. It is shown that the relationships used for voltage control of piezoelectric actuators result from an approximation of the constitutive equations. An exact input/output relationship for piezoelectric actuators is derived and shows that displacement relies fundamentally on charge, not voltage. Experimental verification was obtained to illustrate the differences between driving piezoactuators with voltage control and charge control.

NiTi-Zr high temperature alloys possess relatively poor shape memory properties and ductility in comparison with NiTi-Hf and NiTi-Pd alloys. During martensite transformation of the newly developed NiTi-Zr high temperature shape memory alloys (SMAs) the temperature increases along with Zr content when the Zr content is more than 10 at%. As the Zr content increases, the fully reversible strain of the alloys decreases. However, complete strain recovery behavior is exhibited by all the alloys studied in this paper, even those with a Zr content of 20 at%. Stability of the NiTi-Zr alloys during thermal cycling was also tested and results indicate that the NiTi-Zr alloys have poor stability against thermal cycling. The reasons for the deterioration of the shape memory effect and stability have yet to be determined.

A practically important problem of statics and dynamics of piezoelectric media is the development of applied theories of piezoelements deformation, and in the first turn of plates and shells deformation. In the present work free and forced vibrations of thin elastic plates, made of 6 mm class piezoelectric material are investigated. The hypothesis of Kirchhoff, concerning the stress-strain state of the plates is considered to be valid. In contrast to known investigations no assumptions are laid upon the potential of the electric field. From obtained equations it follows that in the general case transverse vibrations and vibrations of generalized plane stress state are connected. Conditions on plates edges and for the potential of the electric field, under which the planar and transverse vibrations are separated, are investigated. Free vibrations of an infinite plate are investigated with different conditions for the electric field on facial surfaces of the plate. Applicability of known assumptions, concerning the change of the electric potential along the plate thickness is discussed. The problem of forced vibrations of a rectangular plate is considered, when periodically variable in time electric field potentials are given on the facial surfaces. For the case of pure planar vibrations, the found resonant frequencies coincide with those known previously. It is shown, that for certain boundary conditions on plate edges pure transverse resonant vibrations are possible.

An analytical model is presented for the dynamics of contraction of ionic polymeric gels with liquid exudation in the presence of an electrical field. The proposed model considers the dynamic balance between the internal forces during the contraction. These forces are assumed to be due to the viscous effects caused by the motion of the liquid, the inertial forces due to the motion of the liquid in and out of the network, and the electrophoretic forces due to the motion of the charged ions in the solvent as it exudes from the ionic polymeric gel network. The effects of rubber elasticity of the network as well as ion-ion interactions have been assumed negligible in this case compared with the inertial, viscous, and electrophoretic effects. The governing equations, thus obtained, are then solved exactly for the velocity of liquid exudation from within the network as a function of time and radial distance in cylindrical samples. The relative weight of the gel sample is then related to this velocity by an integral equation. This integral equation is then numerically solved to obtain a relationship between the amount of contraction as a function of time, electric field strength, and other pertinent material and geometrical parameters. The results of the numerical simulations are compared with some experimental results on PAMPS contractile fibers and satisfactory agreements are observed.

A novel optical fiber sensor implementation for monitoring structural displacement and load is explored. This new sensor makes use of simple coupling losses between fibers in a hollow core sleeve, and as such, offers variable sensitivity, ruggedness, and design flexibility. Preliminary test results show promise towards the goal of making practical and cost effective fiber optic sensors for field use in structural monitoring. In addition to hardware tests, a computer simulation was written to model sensor performance, and critical design parameters were identified.

The influence of polyacidic additives (silicotungstic acid -- STA, carboxymethylcellulose -- Na-CMC, polymethacrylic acid -- PMA, polyacrylic acid -- PAA) on the molecular mobility of film composition based on polyvinyl alcohol (PVA) in the temperature range 20 - 200 degree(s)C has been evaluated. It has been concluded that interpolymer complexes are formed due to hydrogen bonding of the PVA and polyacidic additive molecules, which results in the change of the PVA stereoregularity. The formation of the complexes depends on the type and concentration of the polyacidic additive, the process of (alpha) -relaxation and, in a certain concentration range of the additive, increases the molecular mobility of the kinetic segments surrounding the complex. The influence of short-term UV-irradiation on the structure and properties of such materials has been investigated. A possibility of the reversible change of molecular mobility and stereoregularity of the examined compositions as a result of short-term UV-irradiation has been established. Introduction of polyacids into the PVA structure gives rise to the electrosensitivity, i.e., the ability to change structure under the action of an electric field. In this case the distinguishing feature is the relation between the molecular mobility and electrosensitivity in the range of parameters where the (alpha) - relaxation occurs.

Piezoelectric fiber composites were introduced as an alterative to monolithic piezoceramic wafers for structural actuation applications. This manuscript was an investigation into the improvement of piezoelectric fiber composite performance through a non-conventional electroding scheme. An interdigitated electrode pattern introduced the major component of electric field into the plane of the structure (along the fibers) and allowed the use of the primary piezoelectric effect. Two models were developed that predict the composite properties. These models examined the trends of composite properties versus fiber volume fraction for various constituent materials. Improvement was seen by comparing the modeled piezoelectric properties of the new electrodes to the conventional arrangement for fiber composites. Several etched electrode fiber composites were manufactured and tested to validate the models. Good agreement was seen for the capacitance, but the piezoelectric constants showed good agreement at only certain fiber volume fractions.