This paper deals with the prediction of the effective piezoelectric coefficient of piezoelectric fiber reinforced composites (PFRC) which measures the induced stress in the fiber direction due to the applied electric field in the direction transverse to the fiber. It has been found that when the fiber volume fraction exceeds a critical value, this effective piezoelectric coefficient becomes significantly greater than the corresponding coefficient of the piezoelectric material of the fiber. In order to assess the performance of the proposed PFRC as a new actuator material, the active constrained layer damping (ACLD) of laminated beam has been investigated. The constraining layer of the ACLD treatment is a layer of the proposed PFRC. The controlled response of the beam is compared with that when the constraining layer of the ACLD treatment is made of piezoelectric material of the fiber. It has been observed that the PFRC performs better than the piezoelectric material alone.

This paper introduces a passive piezoelectric shunt controller, for damping multiple modes of a flexible structure using one piezoelectric transducer. The series-parallel impedance structure has a number of advantages over to previous techniques; it is simpler to implement, requires less passive elements and contains smaller inductors values. The vibration control strategy is validated through experimental work on a piezoelectric laminated cantilever structure.

Electromechanical sensors and actuators are important for robotic and aerospace applications. Among various material, poly(vinylidene fluoride) ir its co-polymers are known to exhibit high piezosensitivity. However, due to their higher electrical resistivity the input impedance of subsequent signal processign circuits is required to be very high. A novel technique to decrease the impedance would be blending PVDF with conducting polyaniline (PANI) but without affecting the piezosensitivyt of PVDF. Polyaniline (PANI) was synthesized by well known standard chemical route using dopants HCl and dodecyl benzene sulfonic acid. These PANI powder were blended with PVDF which was first dissolved in DMAc at 50 degrees C to which were added requisite amounts of two types of PANI ranging from 2 to 25 wt percent, stirred for 24 hours to form a homogeneous mixture which was cast in glass petri-dish, followed by complete solvent evaporation at 50 degrees C and then drying under vacuum for 24 hours to give films of PANI-PVDF blends. The piezo-sensitivity of these blends was measured before and after poling in electrical field. The sensitivity factor was dependent on the composition, type of dopant as well as the electric polarization of the blend. The HCl doped PANI blends in PVDF were highly piezo-sensitive than other blend compositions. These various results have been explained on the basis of compatibility, discrete domain formation, nonlinear conduction process for charge transport, orientation of dipoles, and trapping of space charge at inter-domain sites.

To prepare lead zirconate titanate (Pb(Zr_xTi_1-x)O₃): PZT) thin films at a higher deposition rate and a lower substrate temperature, the PZT films were fabricated by a hybrid process of sol-gel technique and pulsed laser ablation deposition. First, one layer of PZT (about 0.12-0.14 μm) was coated on Si/SiO₂/Ti/Pt substrate by sol-gel process. Then PZT film was deposited at a rate of 0.7 μm/hr by pulsed excimer laser-ablation on the substrate with one sol-gel derived PZT seed layer. A target of Pb(Zr_0.52Ti_0.48)O3 with 20 wt% excess PbO was used. The substrate temperature was about 500 °C. The film fabricated by the hybrid process showed the perovskite PZT phase without pyrochlore phase. The dielectric constant measured at 1 kHz was approximately 1580. The saturation polarization, remnant polarization and coercive field of 0.8 μm thick film were about 46.6 μC/cm², 24.5 μC/cm² and 36.4 kV/cm, respectively. The residual stresses in the thin film stacks were measured by the changes in the radius of curvature of the wafer. A relatively lower tensile stress (approximately 33 MPa) was obtained compared to the sol-gel derived PZT film. Therefore, the PZT films with good electrical and mechanical properties can be fabricated by using the hybrid process of the sol-gel technique and laser ablation.

Effects of EB irradiation on fracture toughness were studied for soda lime glass and glass fiber. The EB irradiation improved the hardness, ductility, fracture stress and fracture toughness. The fracture stress was 1.43 GPa for the glass fiber before EB treatment. The irradiation enhanced the fracture stress. The fracture stress at P_f=0.5 was 1.89 GPa for glass fiber samples treated by 65 Mrad-irradiation. It was approximately 0.46 GPa larger than that before EB treatment. Based on ESR results, the reinforcement can be explained. The changes in fracture stress were in good agreement with the density change in dangling bonds, because a high tensile glass fiber was obtained at 65 Mrad-irradiation. Thus, we confirmed that the glassy cluster structure with high dangling bond density was obtained in high tensile glass fibers prepared by 65 Mrad-irradiation. The EB irradiation controlled the fracture toughness of glasses. To confirm the mechanism, an alpha-aluminum oxide crystal sheet was also studied.

Linear and nonlinear optical properties of Ta nanoparticle composites, fabricated by negative ion implantation, were studied in the visible range. Negative Ta ions of 60 keV were implanted into amorphous SiO₂ and crystalline TiO₂ with a total dose of 3× 10¹⁶ ions/cm². Optical absorption evidently indicated a surface plasmon peak around 2 eV and the peak resulted from formation of nanoparticles embedded in the matrix. The plasmon peak shifted with dependening on the refractive index of the substrates. The laser-induced transient absorption was measured with the technique of pump-probe femtosecond spectroscopy. The transient absorption of the Ta nanoparticle composite in SiO₂ recovered in several picoseconds due to energy transfer from the excited electrons to the lattice via the electron-phonon interaction. The transient response was comparable to that of the noble metals. The electron-phonon coupling was evaluated by the two-temperature model and the coupling constant yielded a value of g = 3.1 × 10¹⁸ W/m³K. The Ta nanoparticle composite has the advantage of thermal stability in comparison with Cu nanoparticle composites.

The acoustic vibrational modes of Au nanorods with aspect ratios between 2.1 and 5.5 have been investigated by timeresolved spectroscopy. The results show that laser excitation launches a coherent vibrational motion which has a period that depends linearly on the length of the rod. Due to polydispersity in the samples, the measured period also depends on the probe wavelength (i.e., for a given sample different probe wavelengths interrogate different length rods). Analysis of the data potentially provides information about the elastic properties of these unique materials.

The size-dependent properties of nanomaterials are currently attracting a great deal of interest in the research community because of the many important potential applications in microelectronic, data storage and sensing devices. The signature optical property of metal nanoparticles is the localized surface plasmon resonance (LSPR), which occurs when collective oscillations of the conduction electrons are excited by light. The LSPR results in wavelength-selective photon absorption, scattering and local electromagnetic field enhancement. The latter contributes to the significant enhancements observed in surface-enhanced Raman scattering (SERS) and other surface-enhanced spectroscopies. Several groups have already demonstrated the enormous potential of compact, integrated SERS sensors for a broad range of chemical and biological sensing applications. However, the systems described so far have generally utilized substrates with a wide range of feature sizes and irregular spatial distributions. These factors contribute to relatively poor reproducibility between sensors. Fabrication techniques based on ordered, self-assembled arrays of nanospheres appear to offer a convenient and inexpensive means for generating uniform structures. Progress in applying these methods to the fabrication of reproducible SERS microsensors will be described.

The mechanism of formation of platinum nanoparticles via chemical reduction of Na₂PtCl₄ in aqueous solution was investigated by UV-Visible Spectroscopy and Transmission Electron Microscopy. Sodium borohydride (NaBH₄) was used as the reducing agent, and tri-Sodium Citrate was used for stabilising the nanoparticles. It is possible to monitor various stages of the reduction process on an observable time scale when the Pt(II) solution is suitably aged. Under appropriate experimental conditions, the theoretically predicted plasmon resonance absorption peak from the well-dispersed Pt(s) nanoparticles is observed at 215nm for the Pt suspensions in citrate medium. It is found that an increased concentration of citrate stabilizer decreases the reaction rate, although there is only a narrow concentration range of stabilizer which produces a stable suspension with well-separated Pt(s) nanoparticles. This conclusion was also supported by the TEM observation of the nanoparticles, which had a very narrow size distribution (between 2 to 6nm).

The sol-gel spin-coating technique is increasingly being used for the fabrication of thin-films with diverse applications in areas that include advanced optics, microelectronics and sensors. The performance quality of the thin film devices is affected by the thickness and homogenity of the film, which are in turn controlled by parameters such as substrate surface quality, viscoelastic properties of the sol, and the spin coating parameters. Processing high quality thin-films is simpler when the desired thickness can be achieved by a single-step coating of sol-gel film. We report on the fabrication of TiO₂ thin films by single-step spin-coating of a well characterised sol on a single crystal Si substrate. By monitoring the viscoelasticity of a titanium alkoxide sol, the thickness of the coated film can be controlled and with proper calibration, the viscoelasticity of the sol can be used as a parameter to fabricate a quality film with desired thickness. The thickness of the spin coated sol-gel films and that of the processed TiO₂ films was evaluated using SEM and ellipsometry. The optical interference phenomenon of Newton's colours, which are obtained for the thin transparent films on reflecting surfaces, can be used to estimate the thickness of the TiO₂ thin-films. This presentation provides details on how this concept can be applied to estimate the thickness of the TiO₂ thin-films in the range of 50 to 200nm. The value determined using this method was comparable to that obtained through ellipsometric and SEM measurements.

This paper describes new concepts the author has proposed and demonstrated to realize metal and polymer based sensitive and/or active structural material systems suitable for smart structures. Most of the developments have been done by simple and innovative methods without using sophisticated and expensive sensors and actuators. The following topics are mainly examined: (1) embedding optical fiber in aluminum matrix to use as sensors; (2) forming optical interference and loss type strain sensors in epoxy matrix simply by embedding and breaking notched optical fiber in it; (3) forming a multifunctional sensor in aluminum matrix for temperature and strain monitoring by embedding an oxidized nickel fiber; (4) fabricating multifunctional composites by using conventional structural materials - i) an active laminate of CFRP/aluminum of which unidirectional actuation is realized by electrical resistance heating of carbon fiber in the CFRP layer and its curvature change can be monitored using optical fiber multiply fractured in the CFRP layer, and ii) a multifunctional aluminum-matrix composite where oxidized titanium fiber is embedded for sensing temperature and strain, generation of heat for actuation.

The Australian Defence Force is increasingly facing escalating costs on through-life support for major platforms (ships, aircraft and land vehicles). The application of smart materials and structures technologies in platform management systems is seen as a very promising approach to reduce these costs and to potentially achieve significant enhancement of platform capability. A new DSTO Key Initiative, 'Smart Materials and Structures', has been recently developed and funded to address these technologies. The Initiative will build on and grow the current activities within DSTO and promote collaboration with external Australian institutes and industry. This paper will present an overview of the Initiative and the generic sensor and system issues inherent in the 'whole-of-platform' and 'whole-of-life' monitoring and management of major defence platforms. Examples for some particular elements of this will be drawn from current work in DSTO. Other presentations in the conference will cover the technical and scientific aspects of these in more detail.

Early detection of adhesive bond degradation using sensing elements embedded within the 100um bond-line of aluminium epoxy adhesive joints has been demonstrated. Sensing elements of varying heights were fabricated at the ends of narrow conductors on a flexi-circuit carrier. This construction simulates the active sensing region on a patented silicon adhesive bond degradation sensor and has been used to characterize the sensing elements without the expense and time associated with fabricating the complete integrated silicon sensor. The highest elements on the flexi-circuit serve both as electrical pickup studs, providing a circuit from the flexi-circuit to the top aluminium plate, and as spacers to ensure that the shorter sensing elements do not contact the aluminium plate. The non-contacting sensing elements are thus arranged to be close to the metal/adhesive interface and are sensitive to any change in conductivity in this region due to release of ions as the interface is degraded by the environment. Accelerated aging tests were performed on flexi-circuit sensors embedded in the bond-line of double cantilever beam specimens. The specimens were immersed in 50° C water and pre-loaded to just initiate a crack. Load on the specimen was then maintained by applying a constant load point displacement with a very low velocity to ensure that the environment would degrade the bond-line in advance of the crack front. The change of load and the conductivity measured by the sensing elements were then logged with time. The onset of bond degradation was detected approximately 10-20 mm ahead of the crack tip.

The economic implication of fleet upgrades, particularly in Australia with military aircraft such as the F-111 and F/A-18, has led to an increasing reliance on composite repair technology to address fatigue and corrosion-affected aircraft components. The increasing use of such repairs has led to a research effort to develop various in-situ health monitoring systems that may be incorporated with a repair. This paper reports on the development of a theoretical methodology that uses finite element analysis (FEA) to model the strain profiles which optical sensors, on or within the patch, will be exposed to under various operational scenarios, including load and disbond. Numerical techniques are then used to predict the fibre Bragg grating (FBG) reflections which occur with these strain profiles. The quality of these reflection are a key consideration when designing FBG based structural health monitoring (SHM) systems. This information can be used to optimise the location of both surface mounted, and embedded sensors, and determine feasibility of SHM system design. Research was conducted into the thermal residual strain (TRS) within the patch. A finite element study revealed the presence of significant thermal residual strain gradients along the surface of the tapered region of the patch. As Bragg gratings are particularly sensitive to strain gradients, (producing a result similar to a chirped grating) the strain gradient on the composite at potential sensor locations both under load, and in the event of disbond was considered. A sufficiently high gradient leads to an altered Bragg reflection. These spurious reflections need to be considered, and theoretically obtained reflections can provide information to allow for load scenarios where the Bragg shift is not a smooth, well defined peak. It can also be shown that embedded fibres offer a higher average thermal residual strain reading, while being subject to a much lower strain gradient. This particularly favors the optical disbond detection system that is being developed. While certification concerns exist with embedding sensors in repairs, this study shows that embedded optical fibre sensors may provide for a health monitoring system with enhanced reliability and sensitivity.

As the replacement costs of military aircraft escalate, there is an increasing trend to operate existing aircraft well beyond their original design life. As the fleet ages, structural problems such as airframe corrosion and cracking are becoming significant issues. In recent years, bonded composite patches or doublers have been developed to repair or reinforce defective regions of the airframe. However certification concerns have limited most application of these bonded composite repairs to secondary structures. In order to alleviate certification concerns, and thus facilitate the implementation of this repair technology to critical damage in primary structure, the 'smart patch' approach has been proposed. This approach involves incorporating sensors into the composite patch to self-monitor patch health. This paper describes the use of optical fibre Bragg gratings to measure the changes in thermal residual strain that occur when a composite patch starts to disbond from the parent structure. Conventionally, the Bragg sensing mechanism relies on a shift in reflected wavelength, which requires the use of costly optical measurement tools. A modified sensing arrangement is proposed, which incorporates two Bragg gratings, and a fibre optic coupler. The reflection from the first Bragg grating acts as a reference source for an active Bragg grating on the patch. This modified arrangement allows a relative wavelength shift to be translated into a change in the optical power, which can be measured easily using a low cost interrogation system. The modified sensing arrangement also allows us to more readily miniaturise the opto-electrical interrogation system, thus enabling these systems to be more easily implemented on operational aircraft.

This paper presents electrically activated paper actuators that can produce a large displacement in the presence of electrical field. This active material is termed as electro-active paper (EAPap). EAPap is made with a chemically treated paper by constructing thin electrodes on both sides of the paper. When 2kV/mm of excitation voltage was applied, more than 3mm of tip displacement was observed out of the 30 mm long paper beam. The principle that dictates the actuation of EAPap seems to be more based on ionic migration effect associated with the reaction of the constituents of the paper. Details of the experiments and results are addressed.

Two kinds of high power actuator film materials prepared by PVD process were developed. One is the The Fe-Pd alloy film, which shows large magnetostriction and high magnetostrictive susceptibility at low magnetic field from earth magnetic field to 1 kOe. Another is the hydrogen storage La-Ni alloy film on a polyimide substrate, which was prepared using a flash evaporation method. The hydrogen storage alloy film showed the reversible shape change, which operated by hydrogen absorption and desorptions. This bi-material actuator was driven by the large volume expansion of hydrogen storage La-Ni alloy film. In this study, the strain changes were measured under different loading stresses. The powers of these two actuator materials were larger than that of Ni-Ti alloy commercially used.

New high responsive Fe-Pd magnetostrictive films with high power were developed and prepared by magnetron sputtering. The in-plane magnetization of Fe-Pd thin film was larger than that of the Tb_0.3Dy_0.7Fe₂ alloy film. The Fe-Pd magnetostrictive films show large magnetostriction and high magnetostrictive susceptibility at low magnetic field from earth magnetic field to 1 kOe. The high magnetostrictive susceptibility of the Fe-Pd alloy films obtained was appropriate as a remote actuator in low magnetic field. If an ideal Fe-Pd magnetostrictive films are developed to apply the micro-machine, offering the advantages of low cost, lightweight and relatively simple design. In order to apply these properties to a practical actuator, load dependence of magnetostrictive susceptibility was serious potential problems. In this study, the magnetostrictive susceptibility changes were measured under different loading stresses. As a result, Fe-Pd alloy film showed high magnetostrictive susceptibility under high film loading stress above 50 MPa.

Analatom Inc. in conjunction with the DSTO (Defence Science & Technology Organisation) has been developing a micro Linear Polarization Resistance (LPR) system for assessing the integrity of high value structures. The device operates on the principle that as a metal corrodes, the oxide formed effectively creates an anodic cell. Hence, if the metal can be separated into two sections, a potential and resistance can be measured between each section. These values can be used to compute the effective mass loss of the device. By matching the material properties of the device with that of the structure whose "health" is being monitored, it is possible to establish a corrosion rate of the structure. Previous research at DSTO has shown that such a system can be fabricated and operated on the micro scale. The task has now been to develop the device into a commercially viable system; it is this development that is examined in this paper. In the original system, a potentiostat is used to evaluate the device for data relating the mass loss during corrosion. This system is now replaced with simplified electronics to reduce both the cost and size of the device. Signal conditioning into the LPR is critical as potentials over 20mV across the terminals can be a source of corrosion of the device. Micro controllers and small board computers are used to run this signal conditioning process and the LPR interface circuit.

A brief description of the theory of passive and active absorbers is presented followed by details of an experimental study into a new design of adaptive absorber. The absorber is a single-layer planar structure based upon the topology of a Salisbury screen, but in which the conventional resistive layer is replaced by an active frequency selective surface (FSS) controlled by pin diodes. The resulting structure has superior reflectivity-bandwidth characteristics compared to conventional passive absorbers of corresponding thickness. Experimental results are presented and compared to those obtained from a transmission line model, and show that the reflectivity response of the absorber can be dynamically controlled over the frequency band from 9-13GHz

Composite materials comprising the environmentally stable conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT), a transition metal/metal salt redox couple in a solid polymer electrolyte matrix have been prepared and characterised. DC and microwave measurements on these materials have shown rapid and reversible changes in their impedances and microwave transmission. The composites may be switched from a high impedance state to a low impedance state for several hundred switching operations with no deterioration in performance when small DC or low frequency AC fields are applied across coaxial discs of the materials from the edges. When the fields are removed, the initial high impedance state is restored. The extent of the change is very dependent on the choice of redox pair and also on the composition of the polymer electrolyte phase. Copper has been shown to give the largest changes in microwave impedance from 185Ω(0V) to 11Ω (5V) at 300MHz. In this paper, we present a series of results for composites containing 26wt% by mass of PEDOT with several transition metal redox couples. The results of lithium tetrafluoroborate concentration in the polymer electrolyte phase on the microwave transmission loss of the PEDOT composite are discussed. The effect of copper metal concentration on the magnitude of the impedance change is also presented along with a proposed mechanism for the switching process.

Several factors affecting the surface morphology, transformation characteristics and shape recovery of co-sputtered NiTi-based shape memory alloy thin films were investigated. It is found that the Ar gas pressure, substrate orientation, deposition temperature and annealing condition all affect the surface morphology. In particular, when under high Argon gas pressure, the deposited film contains surface cracks, while the film is smooth and dense if a 2.3mTorr Argon gas pressure was used during deposition. The film deposited at 450°C on a (100) Si substrate has a rough surface associated with a large distribution of island sizes. Post-annealing treatment leads to a more homogeneous distribution of island dimensions and a smoother surface. On the other hand, the films deposited at 450°C on a (111) Si substrate or on a SiO₂ buffer layer have more homogeneous island sizes. It is also found that both the substrate orientation and the SiO₂ buffer layer dramatically affect the transformation behavior and shape recovery magnitude. Film deposited on (100) Si has a higher recovery strain than that deposited on (111) Si under the same stress. The oxygen in SiO₂ buffer layer may have deteriorated the deposited film, which results in a very low shape recovery strain. Interfacial stress between the substrate and the thin films is found to lower the transformation hysteresis.

TiNiCu films with different Cu contents were prepared by co-sputtering of TiNi and Cu targets using a magnetron sputtering system. Film microstructure, phase transformation behavior and crystallized structures were characterized. The substitution of Ni by Cu in TiNi based films resulted in a dramatic change in martensite structure and film orientation. With the increase of Cu content in the films, both the transformation temperatures and hysteresis decreases significantly from both differential scanning calorimeter (DSC) and X-ray diffraction (XRD) results. However, from both DSC and curvature measurement results, the specific heat and the maximum recovery stress generated during martensite transformation decreases.

The transformation between martensite and austenite is characterized by four transformation temperatures: martensite start temperature (Ms), martensite finish temperature (Mf), austenite start temperature (As) and austenite finish temperature (Af). In actuator design that relies on the shape memory effect, it is important to obtain an accurate measure of these transformation temperatures, especially As and Af. Several methods of determining these temperatures have been reported, but their accuracy and coherence are not clear. Three methods were used to measure the transition temperatures of NiTi wire under different heat treatment conditions: differential scanning calorimetry (DSC); an electrical resistance method, which uses a sudden change in resistance as an indication of transformation; and an applied loading method, where a macroscopic change in displacement indicates the transformation. The results show that the transition temperatures measured by DSC do not correspond to those measured by the other two methods, which are similar. The applied loading method is the most effective for providing practical information about the stress-dependent transformation temperatures. The electrical resistance test gives clearly determined points for Ms and Mf in the cooling resistance-temperature curve, but As and Af are not clearly identifiable in heating process.

This paper presents the results on single-shot laser micromachining of filtered arc deposited TiN films and compares the machining characteristics of the films deposited under partially and fully filtered conditions. Machining performance was evaluated in terms of patterning quality and the ability to perform selective removal of top TiN film with minimal interference to an underlying layer. TiN was arc-deposited onto silicon substrate with a chromium layer on the top. These films were analysed for their composition and microstructure using Rutherford Backscattering Spectroscopy (RBS) and Scanning Electron Microscopy (SEM) before and after laser machining. Under single shot conditions the effect of fluence on the machined features has been investigated. The results showed selective removal of TiN films with a single shot from the underlying Cr layer. Further, this work clearly shows a distinction between the laser machining characteristics of the films deposited under different filtering conditions and substrate temperatures.

Material damage is too fine to be detected by non-destructive tests and difficult to be repaired during use. Therefore self-healing of damage is most desirable to improve the reliability of materials and structures. In heat resisting steels, creep cavities nucleate at grain boundaries by long time use at high temperatures. These creep cavities grow along grain boundaries, from grain boundary cracks by linking up each other and cause the premature and low ductility fracture. Therefore long time creep rupture life and ductility chiefly depend upon the behavior of nucleation and growth of creep cavities. If the growth of creep cavities could be suppressed, the creep rupture properties of creep rupture life and ductility should be improved due to prevention of the premature fracture. Ordinary austenitic stainless steels contain sulfur as impurity and the sulfure segregates preferentially to creep cavity surface because of its high surface actiivty. It is possible to remove sulfur almost completely by doping cerium and adding titanium to the austenitic stainless steels. By adding boron and nitrogen, boron nitride precipitates on creep cavity surface. It was thought that the boron nitride on creep cavity surface suppresses creep cavity grwoth and improve creep rupture life and ductility by its healing effect on cavities.

Silicon on Insulator (SOI) technologies will play a major role for low-voltage, low-power device and MEMS in semiconductor developments. Today four main material technologies, BESOI, SIMOX, Smart Cut and ELO were developed but like BESOI substrate making process has simple steps and less equipment in vestment than others. This paper presents SOI wafer fabricated by direct heat-bonded method, thermally oxidizied Si wafer as handle layer and another prime Si wafer as device layer. By the ductile mode grinding and subsequent polishing methods to fabricate the desired device layer more than 10μm and quality of total thickness variation to be 3μm, roughness 5Å. Excellent quality of bonding SOI wafer with oxidation structure which act as etch stop or sacrificed layer at processes would be widely applied in MEMS, MOS, Optical Device and so on.

A new methodology of systematic design of new materials for various applications is presented in this paper. In particular, a large number of candidate compounds that are formed by all possible combinations of the targeted elements in the periodic table are first screened and shortlisted by artificial neural network techniques. Then the quantum mechanics computation is employed to evaluate the promising candidates selected from the first step. Finally experiments are performed to further examine the computation results. In the present work, we apply this methodology to the study of semiconductors of binary (III-V and II-VI) and ternary (I-III-VI2 and II-IV-V2) compounds. Firstly, we systematically study all possible binary and ternary compounds by using pattern recognition and perform prediction of two important properties, namely band gap energy and lattice constant, with the artificial neural network model. Candidate semiconductors are then selected. On the basis of the above study, we perform first principles quantum mechanics computation for some promising II-VI binary candidates. The first principles study of the ternary candidates will be conducted in the near future, and the experiment study of the binary compounds is ongoing. The model predicted new compounds as well as the developed design methodology may be of interest to general materials scientists including these of smart materials research.

Layered composites have attracted attention for their high specific stiffness, high specific strength, and application specific tailoring of their properties. It is also recognized that layered composites are prone to delamination failure in addition to other failure modes. Consideration of transverse shear on the deformation behavior of the composites is an important aspect in the study of delamination mode failure of such plates. In this paper, we consider the effects of including the transverse shear deformation on the vibration characteristics of layered composites. The formulation is based on the Raleigh-Ritz method using the beam characteristic functions. In addition to including the transverse shear, the formulation is developed for metal-fiber-layered composite plates. This type of laminate construction offers the advantage of both the metallic and fiber properties. Various commonly occuring boundary conditions are discussed. Results are provided showing the effects of the shear deformation on the metal-fiber laminates. The effects of laminate thickness, fiber orientation, and the plate aspect ratios on the free vibration characteristics of the metlal-fiber laminates are given to demonstrate the methodology described.

Under the cyclic loading, stress concentration takes place in the member with circular hole, and it affected to fatigue fracture. Therefore, it is important to obtain the information on the stress concentration of circular hole in the study of fatigue fracture. In the carbon steel strip, it is well known under static loading that Luders' lines which arose by yield stress in the member surface and observed easily by naked eyes exists. The same phenomenon takes place by application of cyclic loading at load ratio: R=0. The direct observation using Luders' lines becomes visible smart sensor that discerns the yielding region. This method is using the property of material itself, and it is a simple method. And, the continuous change of the member surface can discern real-time. The purpose of this study is to obtain basic data on the stress concentation of the vicinity of circular hole by observing the continuous change of the specimen surface in R=0, -1, using the carbon steel strip with a circular hole. And, the stress concentration factor required by FEM analysis and experiment was compared, when yield criterion was changed.

In this paper, plastic region growing process which appeared in crack tip was visualized by stretcher strain, and it was observed using high-speed camera. Then, the fracture toughness value was calculated from the largest plastic region size. It was assumed that the relation equal to the case in which it is static under dynamic load was established, and we carried out dynamic experiment. The dynamic load was measured using piezo load-cell which is difficult to receive the effect of stress wave, the fracture toughness value was decided by the strain gauge method. For comparison, we also carried out static experiment comply ASTM E399-90. Then, the relationship between fracture toughness value calculated from the maximum load and it calculated from the largest plastic region size was investigated.

Giant magnetostrictive (GM) Tb-Fe-Si films were prepared by magnetron sputtering system. X-ray diffraction pattern showed film samples were in amorphous state. The Tb-Fe-Si film (Tb : Fe : Si = 1 : 2.7 : 0.2) prepared at 373 K showed 30 MPa tensile stresses generated by magnetostriction along in-plane direction. The film sample showed about 4.3 μΩm of electrical resistivity that is about 100 times larger than that of TbFe₂ film shown about 5.9 × 10^-2 μΩm. The film sample coercivity was 360 Oe. Magnetization of the film sample at 15 kOe of applied magnetic field in parallel direction to the film surface exhibited 81.0 emu/cc. We prepared giant magnetostrictive thin film with higher electrical resistivity than that of TbFe2 thin film.

Giant magnetostrictive (GM) composite materials with high corrosion resistance and high electrical resistivity were developed. Magnetostriction of the composite material prepared under magnetic field at 19 kOe was about 880 ppm, and the TbFe₂ particle size in the sample was 100-150 μm. Shape anisotropy of the TbFe₂ particles induced by compression and magnetic field caused to increase the magnetization and magnetostriction measured for y axis of the composite samples formed with magnetic field. The composite materials showed high resistivity in order to 10^-2 Ωm and exhibited in order to 10^-2 g hour^-1 of corrosion rate. The corrosion rate of the composite samples increased with increasing TbFe₂ particle size. The corrosion rate of the composite materials may be affected to volume fraction of the TbFe₂ particles exposed area in surface of the composite materials.

In this study, the preparation of giant magnetostrictive Tb-Fe thin films by ion plating process was investigated to induce high magnetostrictive susceptibility and high magnetostriction, especially in respect to the effects of incidence of the vapor flux by geometrical arrangement of the tilted substrate. With increasing substrate angle of Tb-Fe films, the in-plane magnetization at 15 kOe was strongly increased. This indicates that the easy direction of magnetization of Tb-Fe film changed from perpendicular to in-plane by obliquely deposition. The magnetic and magnetostrictive characteristics of the obliquely deposited Tb-Fe films were affected by an oblique anisotropy. The oblique anisotropy of Tb-Fe film may be induced by the shape anisotropy connected with columnar grain.

The crystal growth of Tb-Fe giant magnetostrictive materials under microgravity (μG) and terrestrial gravity (1G) was investigated. The microgravity conditions were obtained by free fall in drop tower facility at the Japan Microgravity Center (JAMIC). TbFe_1.83 alloy with 1 gram and cubic form was prepared for unidirectional solidification under microgravity environment. The samples were melted just before drop and solidified by contact chill against a sample at the period of microgravity after dropping. The microstructure of μG sample was columnar structure and growth direction was aligned in thermal gradient. In 1G sample, the microstructure was weak aligned in thermal gradient. The composition was measured by EDX. The TbFe₃ phase was observed in 1G sample, and no TbFe₃ phase was observed in μG sample, caused by reduction of thermal convection in microgravity environment. In μG sample, the columnar structure that aligned thermal gradient was oriented orientation. The magnetostriction of parallel direction to the thermal gradient was larger than perpendicular direction in μG and 1G. The magnetostriction of μG sample, the measurement direction was parallel to the thermal gradient, was larger than 1G sample caused by microstructure.

We clarified the characteristics of rotating-disk and rotating-concentric-cylinder braking device types using ERF (electro-rheological fluid) with smectite particles. Concerning the steady characteristics of the both braking devices, the current density of the rotating-disk type is smaller than that of the concentric cylinder type. In addition, the input electric power per increment of torque has the same ratio as the enhancement of the shear rate. In contrast, regarding the transition characteristics, the rise time of the torque for the rotating-disk type is shorter than that for the concentric-cylinder type, though the current’s rise time is almost the same in both braking devices. It can be considered that the current density of the rotating-disk type is small and the rise time of the torque of the one type is small due to the influence of the secondary flow. The microscopic tendency of the electric charge can be guessed from the transition characteristic of the electric current.

Stacking triblock copolymers as represented in Fig 1 would be extended more or less indefinitely in both directions to produce very long-range linear nanostructures. The concepts of template fabrication have become increasingly important, isotropic, anisotropic, or hierarchical structures can be obtained, depending on the type of template self-organization mechanism employed. The use of template structures to organise sol gel precursors opens up the huge potential for monolithic materials.

Pb(Zr_xTi_1-x)O₃ films were prepared by pulsed laser ablation on Pt/Ti/SiO₂/Si substrates at room temperature and were crystallized by subsequent annealing. The effect of the Pb content and Zr/Ti ratio in the target on crystalline structure and electrical properites of Pb(Zr_xTi_1-x)O₃ films was investigated. Crystalline phases and structure in the PZT films were investigated by x-ray diffration analysis (XRD). The microstructure and composition of the films were studied by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), respectively. It was found that the adition of 20 wt% excess PbO to the PZT target is necessary to obtain a single perovskite phase. X-ray diffraction analysis results show that the film fabricated from the target with Zr/Ti ratio of 30/70 crystallizes in the tetragonal phase, while the films fabricated from the targets with Zr/Ti ratios of 70/30, 58/42, 52/48, 45/55 crystallite in the rhombohedral phase. The films derived from the target with Zr/Ti ratio of 45/55 and with 20 wt% excess PbO exhibited better electric properties. The remnant polarization and coercive field of the film were 31.28 μC/cm2 and 45.29kV/cm, while the dielectric constant and loss value measured at 1 kHz were approximately 1069 and 0.08, respectively. The results demonstrate that a few micrometers thick PZT thin films derived by laser ablation for use in micro actuators is possible.

We report on the investigation of a series of polyaniline based conjugated polymers with rather different backbone structure and energy gap in order to explore the effect of their molecular architecture on nonlinear optical properties. In particular, we report on the dispersion of x⁽³⁾ in the spectral range covering the rising slope of the optical absorption as well as in off resonance conditions.

Interpenetrating polymer network (IPN) hydrogels base don poly(vinyl alcohol) (PVA) and poly)N-isopropylacrylamide) (PNIPAAm) were prepared by the sequential-IPN method. The IPN hydrogels were analyzed for sorption behavior of water at 35°C and at a relative humidity of 95% using a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used for the quantitative determination of the amounts of freezing and non-freezing water. Free water contents in the IPN hydrogel of IPN1, IPN2 and IPN3 were 45.8, 37.9 and 33.1% in pure water, respectively.

The optical properties of insect nano-structures have been extensively studied. In particular, nano-scale ordered arrays have been reported from studies of the corneal surfaces of some insects and of insect wings showing anti-reflective properties. These arrays have been ascribed to evolutionary adaptation and survival value arising from increased visual capacity and better camouflage against predators. In this study we show that the Atomic Force Microscope (AFM) can effectively reveal and quantify the three dimensional structures of nano-arrays on moth eyes and cicada wings. It is also shown that the arrays present an ideal surface for in situ characterisation of the AFM probe/tip. In addition, a new structure is presented which has been discovered on a termite wing. The structure is similar to that found on the cicada wing, but has a much larger 'lattice parameter' for the ordered array. The function(s) of the array is unknown at present. It could be effective as an anti-reflective coating, but would then be active in the infra-red region of the light spectrum. Alternatively, it may confer evolutionary advantage by virtue of its mechanical strength, or it may improve the aerodynamics of flying. The study demonstrates that natural selection may be a rich source of 'smart' structures.

The atomic force microscope (AFM) allows investigation of the properties of surfaces and interfaces at atomic scale resolution. However, several different operational modes, (imaging, force versus distance and lateral force modes), need to be deployed in order to gain insight into the structure, tribological and mechanical properties. A new method, based on a variation of the force versus distance mode, has been developed. In essence, a coupling of the deformational modes of the probe is exploited whereby the tip is induced to undergo lateral travel in response to application of an out-of-plane force (and thus normal bending of the force-sensing lever). The lateral travel induces in-plane forces that are then measurable as a consequence of stimulation of the 'buckling' deformational mode of the lever. Due to the lever geometry, the technique offers an increase in resolution of an order of magnitude over existing AFM methods for measurement of atomic scale stick-slip events. In addition, the method allows measurement of the lateral deformation of the sample as well as scanner calibration. Outcomes will be demonstrated for atomically flat surfaces such as WTe2 and highly oriented pyrolytic graphite.

The osseointegrated trans-femoral implant system provides a direct anchoring technique to attach prosthetic limb. This technique was first introduced PI Brenmark in Sweden. The UK had the first clinical trial in 1997 and currently has 6 active limb wearers. The success of this procedure has the potential for improved gait function and mobility, increased employability and significant long-term improvements in the quality of life for above knee amputees. However, the significant load involved in the trans-femoral implant system has caused permanent deformation and/or fractures of the implant abutment in several occasions. To protect the implant system, the implant abutment in particularly, an overloading protection device was introduced. The device uses mechanical mechanism to release torsion overload on the abutment. However, the bending overload protection remains unsolved. To solve the problem, a new overload protection device was developed. This device uses SMA component for bending overload protection. In this paper, the results of non-linear finite element modelling of the SMA and steel (AISI 1040) components were presented. Experiments were also carried out using steel components to assess the design which is based on the non-linear property of the materials.

In recent years, fiber optic sensors have been used for structural health monitoring because of the advantages they have over conventional strain gauges, such as multiplexing capability and immunity to electromagnetic interference (EMI). In addition, they have ability to monitor multiple parameters simultaneously, which is of significant benefit to researchers. However, this diverse sensitivity can cause "cross coupling" leading to imprecision in measurement. In this paper, we report our results on the development and testing of a temperature compensated fiber Bragg grating strain sensor. Results show that the proposed sensor structure can be used to effectively compensate for temperature variations in strain measurement.

Novel electrorheological (ER) particles consisting of polyaniline (PAn) core and BaTiO₃ shell of different thickness were synthesized using an advanced method of combining controlled assembly with sol-gel process to integrate semi-conductivity of polyaniline and ferroelectricity of BaTiO₃. The PAn-BaTiO₃ core-shell nanocomposite particles were well characterized with TEM, XRD, FT-IR, XPS and TG-DTA. The electrical properties of the PAn-BaTiO₃ core-shell nanocomposite particles was tested and the ER behaviors of the ER fluids based on the PAn - BaTiO₃ particles with volume percent of 20 percent dispersed in chlorinated paraffin oil were investigated under DC electric field. The relationship between the ER activity and the electrical properties of the core-shell particles were discussed. The results showed that the PAn-BaTiO₃ shell-core nanocomposite particles with different shell thickness could be obtained by controlling the composition of sol solution and the coating times. There are chemical bonds between PAn core and BaTiO₃ shell, which are helpful for making them combined firmly. The ER effect of the PAn-BaTiO₃ core-shell nanocomposite particle was far stronger than that of pure polyaniline and barium titanate which were synthesized by the same method. For the PAn-BaTiO₃ core-shell nanocomposite, Both the BaTiO₃ shell thickness and polar groups of -OH existing on the surface of the particles have important influences on the ER effects.

Thin films of Se_80-xTe₂₀Pb_x (0 < x < 2) glassy semiconductors have been prepared by thermal evaporation of bulk material of the above composition prepared by melt quenching technique. The glass transition temperature "T_g", the peak crystallization temperature "T_p" and the melting temperature "T_m" of the bulk samples have been estimated from the Differential Scanning Calorimetry (DSC) data. The DSC studies were performed at a heating rate of 10 deg/min. It has been found that "T_g" initially decreases with small addition of Pb (x = 0.6), however its value increases with further addition of Pb (x > 0.6). This indicates that the addition of Pb (x >0.6) cross-links the already existing Se-Te chains, which in turn increases the chain length and results in the increase of T_g. The dc conductivity of the films has been measured as a function of temperature and is found to be activated in the entire temperature range. Its value increases from 10^-9 to 10^-5 (Ohm-m)^-l with the addition of Pb to Se-Te system. The dc activation energy has been found to decrease from 0.67-0.23 eV with increase in Pb content. The optical energy gap determined at room temperature is found to decrease from 1.67-1.34eV with the addition of lead to the Se-Te matrix. The results are explained on the basis of enhanced valence band tailing when Pb is incorporated into the Se- Te system.