We produced a new metal core-containing piezoelectric fiber by means of the hydrothermal method. The insertion of a metal core was significant in view of its greater strength than ceramic materials and in that electrodes are nol required in the fiber's sensor and actuator applications. A new smart board was designed by mounting these piezoelectric fibers on the surface of a CFRP composite. It was shown that these complex fibers can function as sensors and actuators. In order to evaluate the sensor and actuator However, using the hydrothermal method, a piezoelectric layer of about 20μm thickness can be formed on the titanium wire surface, whereas the conventional PZT clad is too thin for use as an actuator. In this paper, we solve this problem using extrusion method, and develop a thicker PZT ceramics than that of a PZT-clad fiber. Thirty-one piezoelectric fibers were embedded in a CFRP composite material, and the sensor and the actuator function were evaluated. We showed that self-sensing was possible using this smart board.

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Fabrication and applications of Pb(Nb,Ni)O_3-Pb(Zr,Ti)O_3 (PNN-PZT) piezoelectric ceramic fibers with a metal core is introduced. The green fibers were fabricated by extruding a mixture of PNN-PZT powder and organic solvent together with a 50 μm Pt core. Fibers of 250 μm in diameter and a few centimeters long are obtained without any cracks after sintered at 1200℃. The core is precisely located at the center of the fibers. The boundary of the PNN-PZT ceramics and the Pt core was investigated by cutting the fiber along the cross-section and the longitudinal direction, and observing them with a scanning electron microscope. The ferroelectricity and piezoelectricity of a single fiber were confirmed. The polarization versus electric field relationship was measured by a Radiant RT-6000 and the result exhibits the typical ferroelectricity of the PNN-PZT material. The strain versus electric field relationship also shows the typical hysteresis of piezoelectric materials due to the d_3 effect. The sensor and actuator functions of the fibers are confirmed by bonding three fibers on a composite beam. The vibration sensor using a single fiber was also developed.

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Acoustic emission (AE) method is a powerful tool to monitor in-situ damage in materials because elastic waves are generated due to brittle cracking or frictions. Conventional AE techniques use a piezoelectric ceramic element and attach it to samples in order to detect AE signals at the surface of samples. Microfractures in materials are quantitatively analyzed by the detected waveforms such as location, size and fracture mode. However, conventional AE transducer cannot be used at elevated temperature or severe environment. Laser based ultrasonic (LBU) technique has been developed to characterize materials properties and detect flaws in materials. We have developed a non-contact AE technique to detect AE signals in various environments where conventional AE technique cannot be applied. AE during sintering of alumina ceramics and thermal spying of alumina powder on steel substrates were successfully measured by laser interferometers. The effect of processing parameters on AE behavior was clearly observed by analyzing AE waveforms.

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Recently complex-shaped and integral molded fiber reinforced plastics (FRP) have been developed due to low cost and high strength. In the molding of the FRP parts, it is important to know residual strain produced during the molding. In the present paper, strain behavior of carbon fiber reinforced plastic (CFRP) textile composites during a resin transfer molding (RTM) process was measured by using FBG (Fiber Bragg grating) fiber optic sensors From the results of the strain monitoring, it was found that the embedded FBG sensors could measure small variation of strain in the specimens during the molding. However it was shown the sensor output jumped during cooling. To consider the reason of the jump, the transition of the reflected spectra from the sensor Was investigated. In addition, tensile and thermal loading tests were conducted after the molding. From the experimental results, it can be concluded that the jump of the sensor output shows jump of strain behavior of the specimens during the cooling. We consider that the jump of strai!l behavior was resulted form frictional constraint between the specimen and the mold. Since FBG sensors do not need calibration, certain residual strain can be obtained to conduct the measurement after unmolding.

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Delamination is a significant defect of laminated composites. The present study employs an electrical resistance change method in an attempt to identify internal delaminations experimentally. The method adopts reinforcing carbon fibres as sensors. In our previous paper, an actual delamination crack in a Carbon Fiber Reinforced Plastics (CFRP) laminate was experimentally identified with artificial nerura networks (ANN) or response surfaces created froma large number of experiments. The experimental results were used for the learning of the ANN or for regressions of the respons surfaces. For the actual application of the method, it is necessary to minimヌze the number of experiments in order to keep the cost of the experiments to a minimum. In the present study, therefore, FEM analyses are employed to make sets of data for the learning of the ANN. Firstly, the electrical conductivity of the CFRP laminate is identified by means of the least estimation error method. After that, the results of the FEM analyses are used for the learning of the ANN. The method is applied to the actual delamination monitoring of CFRP beams. As a result, the method successfully monitored the delamination location and size using only ten experiments.

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This paper describes research developments of intelligent materials and system. Based on nanotechnologies related to magnetic field, electron charging, dangling bond, point defects, atomic distance, proton and phase transformation, smart and intelligent materials with three intelligent principle functions of power, sight and reliability successfully developed in 2003 and 2004 were introduced. To obtain high power, unimorph actuators operated by hydrogen gas and magnetic field were developed. Furthermore, recent developments of processing related to percussion welding and electron beam irradiation will be introduced for smart materials and systems.

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New method to fabricate the metallic closed cellular materials for multi-functional material has been developed. Powder particles of polystyrene and polyimide resin coated with a nickel-phosphorus alloy layer using electro-less plating were pressed into pelicts and sintered at high temperatures by a furnace and a spark plasma sintering (SPS) system. A metallic closed cellular material was then fabricated. The physical, mechanical and damping properties of this material were measured. The density of this material is smaller than that of other structural metals. The results of the compressive tests show that this material has the different stress-strain curves among the specimens that have different thickness of the cell walls and the sintering temperatures of the specimens affect the compressive strength of each specimen. Also, it seems that the this closed cellular material has high-energy absorption and the internal friction of this material was same as the that of aged pure aluminum

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This paper summarizes some recent works related to the multibody system dynamics (MSD). First, a finite element model of track in contact with wheel and terrain is introduced, which can be integrated into a multibody dynamics code for simulating tracked vehicles. Second, an automated design and analysis program, OKAD, is introduced for evaluating the dynamic characteristics of accessory drives. Third, an Engine Modeling Template (EngTmp) is introduced, which employs a relative coordinate system that results in a simplest set of ODE's, which can be used to simulate engine systems with high efficiency in support of upfront designs.

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