The acoustic emission (AE) method is one of the powerful real time health monitoring tolls. The AE source wave analysis is a method of estimating the parameters of the clack volume and cracking generation time of micro-cracks. In this study, we developed AE waveform simulation using 3D-FDTD method to apply to AE source wave analysis. Displacement waveform by displacement sensor and simulation waveforms was first compared. An artificial AE signals were produced by Hsu-Nielsen source on the thin plate with a thickness of 10 mm. A high correlation was obtained between developed AE simulation waveform and displacement waveform detected by the sensor. Simulation waveform with involving a sensor response was next compared. Sensor response was used in our previous study. Waveform characteristics between simulation and experiment were similar, however, correlation was low. Correlation between wavelet contourmap of these waveform were also low. These were occurred by sensor response.

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The rotating components has used commonly for mechanical components. However, fatigue monitoring of rotating components is difficult during the operation because surface of rotating component can not contact the sensor. In this study, fatigue monitoring of rotating components using non-contact AE (Acoustic Emission) monitoring system was developed. The developed system was applied for monitoring bending fatigue in a rotating component. Load was applied at tip of specimens and specimens were rotated at a rotation frequency of 8 Hz during rotary bending fatigue test. AE signals were detected at approximately 97 % to fatigue life during the test. Source locations of AE signals in the axial directions were identified within error of 25 mm from a crack. Crack surface reached the 41 % of fracture surface at detected initial AE signals. Elements of C and O were found in the contact surface by EDS analysis. We estimated that AE was generated by fretting from fracture surface.

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We are researching about the clamp-on ultrasonic flowmeter which measures the flow rate of low-pressure gas such as atmospheric pressure. Since acoustic impedances differ greatly by metallic plumbing and internal gas, it is difficult for ultrasonic wave to propagate into the inner gas. We verified input method of ultrasonic wave by perfprming a basic experiment. The basic experiment used two parallel plates. One pair of two ultrasonic transducers were oppositely placed on the outer sides of both plates. It was confirmed that the ultrasonic wave can propagate from one side to another side.

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In this study, we investigated the relationship between microstructural change and the evolutions of two nonlinear acoustic characterizations, resonant frequency shift and other three-wave mixing, with electromagnetic acoustic resonance (EMAR) throughout the creep life in welded joint for high Cr ferritic heat resisting steel, ASME Grade 91. EMAR was a combination of the resonant acoustic technique with a non-contact electromagnetic acoustic transducer (EMAT). We used bulk shear-wave EMAT. Creep tests of thick welded joints specimens were interrupted at several time steps at 873 K, and 90 MPa. Two nonlinear acoustic parameters and ultrasonic attenuation decreased from the start to 20% of creep life. After that, they gradually increased to rupture. Creep void initiated from 20% of life, and increased to the rupture. The changes of two nonlinear acoustic parameters, attenuation caused by the microstructural change related to creep void initiation and growth. This noncontact resonance-EMAT measurement can monitor the evolution of nonlinear acoustics throughout the creep life and has a potential to assess the Type IV creep damage advance and to predict the creep life of high Cr ferritic heat resisting steels.

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T(0,1) mode guided wave is converted into the circumferential SH waves in the defect portion, it has been reported that the resonance occurs at a specific frequency. In this report, we show that the circumferential defect widths depends on the resonance frequency of the circumferential SH waves.

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We calculated transient waves in a steel plate loaded with water on a single side for dynamic loading from a point source on the other water-free surface. The calculation results proved that a quasi-Scholte wave is promising for long range inspection of water-loaded plates due to its prominent characteristics of small-dispersion and zero-attenuation. The quasi-Scholte wave has superior generation efficiency in low frequency range due to its broad energy distribution across the plate thickness, while it is localized near the plate-water interface at higher frequencies, which means that it has superior detectability of inner defects.

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Lamb waves are ultrasonic waves to propagate a board. Generally insert wedge in the excitation of Lamb waves between a sensor and boards, and it is necessary to set the angle for critical angle. We produced a water coupled Lamb wave sensor with water as wedge in the past. It was excited in high efficiency and was able to detect Lamb waves. However, a lot of spurious signal that affected a measurement were detected. I focused on a rubber have high decrement efficiency. A rubber has sound impedance near to water. I used a rubber because it damp spurious signal. I inspected the effect of a rubber in this announcement.

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In this study, we investigated nonlinear ultrasonic characterizations with NRUS (nonlinear resonant ultrasound spectroscopy) and three-wave mixing methods of the aluminum alloy plates subjected to zero-to-tension fatigue loading. In NRUS, the resonant frequency of an object is studied as a function of the excitation level. As the excitation level increases, the elastic nonlinearity is manifest by a shift in the resonance frequency. The combination with PZT and EMAT (electromagnetic acoustic transducer) were applied to for NRUS method. In three-wave mixing method, two intersecting ultrasonic waves produce a scattered wave when the resonance condition is satisfied. The wave amplitude was measured. Nonlinear ultrasonic characterizations with these two methods exhibit high sensitivity to micro-structural change of the damaged material. They rapidly increased from 60 % of fatigue life to the fracture. Nonlinearity in three-wave interaction methods sensitivity is higher than that in NRUS. These noncontact resonance-EMAT measurements can monitor the evolutions of ultrasonic characterizations throughout the fatigue life and has a potential to assess the damage advance and to predict the fatigue life of metals.

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We develop shear vertical (SV)-wave point-focusing electromagnetic acoustic transducer (PF-EMAT) for the purpose of detecting stress corrosion cracking (SCC) at the inner surface of stainless steel piping, and effect of driving frequency of PF-EMAT on dynamic range for crack detection is evaluated. Two PF-EMATs with different driving frequencies (1.1 and 2.0 MHz) are developed, and slit defects of different depths (≤ 1.45 mm) located at the bottom surface of SUS304 stainless steel plate of 20 mm thickness are detected. PF-EMAT is placed on the upper surface, transmits SV waves, and receives SV waves reflected by the slit defects. At driving frequency of 1.1 MHz, amplitude of received signal monotonically increases as the slit depth increases. In contrast, at 2.0 MHz, amplitude sharply increases as the slit depth increases, and reaches the maximum at a depth of 0.8 mm, beyond which amplitude decreases. From these results, 1.1 MHz PF-EMAT is suitable for estimation of crack depth, and 2.0 MHz PF-EMAT is suitable for detecting small cracks.

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Pipes in power plants tend to be damaged at the pipe elbows and lower reach of orifices by flow accelerated corrosion and erosion. As one of the conventional techniques, an ultrasonic thickness meter is generally used to measure the main pipe thickness and detect the corrosion wastage in power generation plants. However, this requires plant outage time and cost to dismantle and reassemble the heat-insulating coat of the pipes. To solve these problems, we developed a new measurement technology by combining ElectroMagnetic Acoustic Transducer (EMAT) and fiber-optic sensors. Since it can be put between the pipe and the heat insulator, this sensor enables us to measure and monitor the thickness of the pipe online. This report describes how to detect LDI (Liquid Droplet Impingement) erosion on inner surface of pipes with EMAT and fiber-optic sensor.

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This study aims to identify source of AE detected A6061-T6 and A7075-T651 aluminum alloys with two cracks during fatigue test under various ΔK. Most AE were detected at near maximum load. Fractured inclusions were observed on fracture surface and would be a source of the AE at maximum load. In the many inclusions, vertical cracks were also observed. AE generation frequency increased with crack propagation rate. However, the AE generation frequency in A7075 alloys was about 10 times that in A6061 alloys and it corresponds to difference in total numbers of crack including vertical cracks. At coalesce of two fatigue cracks, much AE was detected at low load. The source of those AE could be a friction of crack surface since the two cracks exists in parallel to loading direction. These waveforms and amplitude of AE by fracture of inclusions were similar to those by friction of crack surface.

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We have imaged plastically deformed region in a 5052 aluminum plate under tensile loading, unloading and reloading processes by using an immersion local resonance method. By transmitting large-amplitude burst wave of which frequency is a through-thickness resonant frequency of the plate, dislocation loops in plastic zone are forced to vibrate. The higher harmonic amplitude excited by the dislocation movement is mapped for the transducer position. The extension of plastic zone under monotonically increasing loading, decrease in harmonic amplitude under unloading process and marked extension of plastic zone in reloading up to 0.4% plastic strain are clearly imaged.

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With an acoustic emission technique, the method for stress corrosion crack detection has been studied. However, piezoelectric type AE sensor which is generally employed in AE measurement is not allowed to use in corrosive liquid because it has electronic components in it. On the other hand, an optical fiber sensor can be immersed into liquid because the fiber is made of SiO_2 and have no electronic circuit in a sensor portion. In this study, an immersion type optical fiber AE sensor with a parabolic reflector was developed. The parabolic reflector enables to improve its sensitivity and directivity of ± 11 degree in full width half maximum. The sensor is able to detect liquid-borne AE from stress corrosion cracks in sensitized SUS 304 steel.

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In the former works, ultrasonic thermometry, an effective method to measure temperature distributions near heated surface, had successfully been applied to in-situ monitoring of temperature rise in a friction surface. In the method, the temperature profiles including the friction surface temperature are quantitatively determined by a combined method consisting of ultrasonic pulse-echo measurements and a finite difference calculation for estimating one-dimensional temperature distributions along the direction of ultrasound propagation. Since it is necessary for the practical use of the method to consider the reduction of the specimen length due to surface abrasion by the friction, a new method based on finite difference calculation using non-uniform grid is developed and its feasibility is demonstrated.

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We propose a new measurement method for simultaneously measuring thickness and sound velocity for soft materials such as a conductive polymer film and stacked induced pluripotent stem cells (iPS cells). Using the 75 MHz underwater-type ultrasound transducer, simultaneous thickness and sound velocity measurement has been carried out by combining the acoustic resonant spectroscopy and pulse-echo measurement. The advantage of this method is that the thickness can be derived without using the known value of sound velocity. The thickness of the conductive polymer film and the stacked iPS cells on metal substrate are measured at 10.4 μm and 16.0 μm, respectively. The thickness of conductive polymer and the staked iPS cells agrees well with the reference measured by the confocal laser microscope. T These results indicate that the developed measurement method can be one of the potential candidates for the real-time thickness measurement for the soft materials. For future work, the thickness of living iPS cells should be measured in real time. Using this method, we would like to figure out the relationship between the stacked state and the differentiation of iPS cells.

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The condensation rate of vapour bubbles is an important parameter to determine the condensation heat/mass transfer in subcooled boiling. It is defined by v_c=dR/dt where R is the bubble radius and t is time. In the definition, bubbles are assumed to have a spherical shape. Accurate measurement of v_c is required to understand the flow physics. Together with that, the measured data is needed for numerical prediction of the flow behaviors. A novel method has been developed in this study to measure v_c by using multiwave ultrasound. In the method, the velocity of the top and bottom interfaces of condensing moving bubbles are measured by using two ultrasonic frequencies (namely multiwave ultrasound). Thus v_c can be calculated based on the velocity difference between the two measurement lines. The accuracy of the measured data of v_c has been well confirmed by comparison with the result of the optical visualization and analysis of the subcooled boiling in a vertical pipe (at atmospheric pressure). The data of ohen can be exploited for the analysis of the interfacial heat transfer coefficient in subcooled flow boiling. Such measurements and analyses can be applied to the high temperature/pressure flow conditions in industrial and engineering practice.

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The purpose of this study is to identify internal defects of stainless steel centrifugal casting tube using electromagnetic ultrasonic flaw detection method. However, electromagnetic ultrasonic flaw detection method is low energy conversion efficiency. Further stainless steel is large wave attenuation. Therefore, it is not possible to identify a defect in an electromagnetic ultrasonic flaw detection method. So it aims the recognizing defect by adapt the impedance matching to the electromagnetic ultrasonic flaw detection method. It was examined impedance matching in the case of varying the power supply frequency in this paper.

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A new method is proposed to detect a tilted/deflected planar flaw on the back surface of a plate using the interference of ultrasonic waves. Parameters for flaw evaluation are developed and examined through experimental results for artificial flaws. The distingwish of the tilted/deflected flaw is estimated by parameter, which shows the difference in the first minimum amplitude of the interference fringe. The effect of tilt angle of the flaw on parameter, which indicates the amount of asymmetry of the interference fringe along the direction normal to the flaw, is investigated. Tilted angle larger than 10 degree can be identified from the deflected flaws using the present method with a tilt angle of from the normal direction of the inspection surface.

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Ultrasonic testing is applied to evaluate cure degree of resin in GFRP laminates. Polymer based composite materials are widely used to repair aged structures in civil engineering because they have high specific strength and good corrosion resistance. To prevent inappropriate repair works, nondestructive evaluation of resin cure after construction is required. In this study, propagation velocity of ultrasonic waves is used as cure index of resin, and through-thickness and in-plane ultrasonic measurements were conducted to compare the sensitivity to resin cure between them. It is found that evaluation of resin cure with bulk waves in the through-thickness direction is more reliable than that with guided waves in the in-plane direction.

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Ultrasonic testing is applied to GFRP laminates degraded with hot water through one surface. GFRP vessels have been used to store acid solution and alkaline solution because of their excellent corrosion resistance. In these days, integrity evaluation of GFRP vessels has attracted much attention with the increase of aged vessels. Since degradation proceeds gradually from the inner surface of a vessel, damage evaluation in the through-thickness direction is required. In this research, GFRP laminates are degraded with hot water through one surface. Then, through-thickness ultrasonic inspection is conducted to evaluate damage state of the composites. Beside wave attenuation and velocity, characteristics of reflected waves from the degraded surface are analyzed. It is found that envelope analysis of reflected waves from the degraded surface is useful for damage evaluation of composites.

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Aerosol deposition (AD) method is a novel deposition method. Ceramics films can be formed on various substrate at room temperature by using this deposition method. Dielectric and mechanical properties of ceramics films such as PZT, BT and Al_2O_3 has been reported. In this deposition method, the film formation is complete at room temperature. We think that various composite films would be formed. However, formation of composite films by using this deposition method has not been reported in detail. The purpose of this study is to form Ni-W composite film, and to investigate mechanical properties and microstructure of the composite film. Ni-W composite films were formed on a glass and stainless substrate. Cross-sectional microstructure of these films was observed by FE-SEM and TEM. Microhardness of these films was measured by Vickers hardness tester. From the results of this study, dense Ni-W composite films with thickness over 10gm were able to form on the glass and stainless steel substrate. Microhardness of Ni-W composite film increased from Hv220 to Hv380 when weight ratio of W powder in the mixed powder was increased. Film formation and microhardness of the Ni=W composite film depended on the condition of raw powder used for the deposition test in AD method.

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The purpose of the present study is to develop a novel implant material which has a superior biocompatibilities and high strength by means of a coating technology. In order to achieve the purpose, the cold spray technique was selected and used to surface modification method of a titanium alloy. It was revealed in previous study that the cold sprayed porous Ti coating (CS-Ti coating) had a low elastic modulus, high adhesion and enough tensile strength in the post-sprayed heat treated (PSHTed) CS-Ti. coating. In this study, the change in the microstructure of the coating by the cyclic compressed indentation loading was investigated.

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Thermal conductivity of thermal barrier coating (TBC) with porous microstructure is examined by characterizing porosity, pore size and its orientation in order to contribute to develop advanced TBC with a low-thermal-conductivity. In this study, TBC with various kinds of porosity is deposited by atmospheric plasma spraying technique, and porosity was controlled by adjusting a weight percent of polyester powder involved in a spraying powder. Thermal conductivity for free-standing TBCs is measured by laser flash measurement. In order to relate between microstructure and thermal conductivity of TBCs, steady-state heat transfer analysis is performed using the finite element model reconstructed from SEM picture. As a result, it was found from laser flash measurement that thermal conductivity was decreased exponentially with increasing porosity, and was coincided completely with the result estimated from finite element model. In order to clarify influence of shape and orientation of pore on thermal conductivity, the model idealized by which elliptical-shaped pore was regularly arranged was also analyzed. It was confirmed that thermal conductivity could be affected by area projected on the plane normal to a heat flow direction.

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The Young's modulus of thermal barrier coating (TBC) is an essential mechanical property as it is required for calculating the parameters of material mechanics. In this study, we developed the evaluation method of the Young's modulus of TBC based on the primary bending resonance of a TBC system specimen. First, we derived the closed form solution for the Young's modulus of TBC by using the equation of the motion for bending vibration of a composite beam. The solution provides the Young's modulus of TBC by the measured resonance frequency and the known values, which are dimensions, densities, and Young's moduli of subsurface layers. Next, we performed sensitivity analysis of these input errors. It was found that the most important input values were thickness and properties of the substrate. Finally, it was experimentally confirmed that the Young's modulus of TBC was obtained accurately by the method.

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Thermal barrier coatings (TBCs) are the indispensable technology for hot-section components of an advanced industrial gas turbine. A TBC consists of a metallic bond-coat (BC) and a ceramic top-coat (TC) on a superalloy substrate. The reliable data of various properties on the coatings have been required to design the superior TBC. Especially, the Young's moduli of the BC and the TC are important mechanical properties to evaluate mechanical and thermal stresses. In the present study, the Young's moduli of TBCs were measured using the flexural resonance method. Several kinds of TBC specimens were made by plasma sprayings with different conditions. The Young's modulus was determined according to a new analytical approach proposed for a multi-layer model. It was confirmed that this approach can obtain reliable data of the Young's modulus and is very effective for the TBC. Furthermore, the Young's modulus of the TC was found to be strongly dependent on its microstructure. The TC with the higher porosity and microcracks between splats exhibits the low Young's modulus.

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Thermal barrier coatings (TBC) is indispensable technique for advanced gas turbines. However, thermally grown oxide (TGO) is formed at the interface between top coating (TC) and bond coating (BC) of the TBC in a high temperature environment, and the TGO can induce delamination or spallation of the TBC. By Cerium (Ce) addition to conventional CoNiCrA1Y bond coat material, a wedge-like TGO is formed in a high temperature environment and improve delamination resistant properties drastically. In this study, several kind of TBC specimens with Ce added BCs, which exposed to 1100℃ in air for several exposure times, were prepared. Moreover, four-point bending tests were carried out under tensile and compressive loading conditions for TBC. In the case of tensile loading, delamination resistance property of TBC specimens with Ce added BCs were obviously higher than that of the TBC with conventional BC, and the delamination resistance property of TBC specimens with Ce added BCs were maintained up to 500 hours exposure. In the case of compressive loading, TBC specimens with Ce added BCs showed almost same strength as the TBC specimen with conventional BC.

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In this study, we developed a new MgSiO_3 piezoelectric mixed crystal by using first-principles DFT calclations. Recently, Bio-MEMS device is developing for health monitoring system and drug delivery system. Piezoelectric materials are required biocompatibility and high piezoelectricity for actuators and sensors in the devise. MgSiO_3 with perovskite-type oxide ABO_3 is biocompatible piezoelectric materials. However piezoelectricity of MgSiO_3 is lower than that of conventional piezoelectric material. In this study, we enhanced piezoelectric property of MgSiO_3. First, we designed a mixed crystal by biocompatible element set to A or B sites of MgSiO_3 such as (Mg_<1-x>,A_x)SiO_3 and Mg(Si_<1-x>,B_x)O_3 by using first-principles DFT calculations. As a result, Mg(Si_<1/2>, Ti_<1/2>)O_3 indicated highest piezoelectric property and a possibility of a new biocompatible piezoelectric material. Next, we tried to generate Mg(Si_<1/2>, Ti_<1/2>)O_3 piezoelectric thin film by using a reactive RF magnetron sputtering. Doping Ti to MgSiO_3 was realized by changing the sputtering target putting some Ti pellets on MgO-SiO_2 sintered body target. Composition elements ratio was measured by using EDX. As a result, we succeeded the development of Zn doped MgSiO_3. And we measured piezoelectricity by using FCE. Finally, we found a new highly piezoelectric mixed crystal Mg(Si_<1/2>, Ti_<1/2>)O_3

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In this study, crystal orientation analysis of metal-core piezoelectric fiber that embedded in aluminum matrix was investigated. Piezoelectric ceramics are widely used due to their piezoelectric effect as excellent transducers. In other hands, there is a problem that the piezoelectric ceramics very brittle. In order to solve this problem, it was successful that embedding a metal-core piezoelectric ceramics fiber in an aluminum matrix without fracture by using the Interphase Forming/Bonding method that proposed by Asanuma. While this process, compression residual stress is applied to the metal-core piezoelectric ceramics fiber due to difference of coefficients of thermal expansion between the fiber and the matrix. The purpose of this study is evaluation of the polarization of the fiber under the residual stress by EBSD (Electron Back Scatter Diffraction patterns) analysis. According to the results, orientation of (001) that is axis of the polarization into poling direction was disturbed by the residual stress. This means that movement of off-center ion in perovskite structure was obstructed by the residual stress.

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This paper describes analysis of output voltage anisotropy of metal-core piezoelectric fiber/aluminum composite. In this study, the metal-core piezoelectric fiber/aluminum composite was analyzed by finite element method to clarify the reason for the output voltage anisotropy appears. The strain direction dependency of output voltage of the composite has been confirmed by vibration test and impact test in the previous studies, and the strain direction dependency was shown to be described by a simple strain decomposition model. This anisotropy was investigated that was caused by not taking the constant angle between the stress and polarization directions of piezoelectric ceramics because the polarization directions were radial directions. In this paper, it was examined whether the above-mentioned hypothesis is satisfied by the finite element analysis to estimate the output voltage produced by the load distortion of the various directions to the fiber which was embedded in the matrix, and it was found that the hypothesis is correct by the finite element analysis.

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This paper proposes a method for identifying impact damages induced in a sandwich panel composed of CFRP facesheets and an aramid honeycomb core. In the present method, the location and the force history of the impact are identified using the sensor responses measured with piezoelectric sensors, and the identification results are used to estimate the impact damage. The identification method is an experimental one so it does not require any analytical model of the structure. Experimental transfer matrix, which relates the impact force and the sensor response, is used to identify the force history. The results reveal that the impact damages in CFRP sandwich panels can be estimated by the shape of identified force history of the impact.

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An offshore GPS buoy network is one of the most important core equipments in a tsunami early-warning system. To improve the accuracy and reliability of the system, dense deployment of GPS buoys is expected. Existing designs of GPS buoys are, however, not suitable of the dense deployment because of their heavy, bulky, and expensive design. Application of smart structures and materials technologies, such as smart composites, smart sensors, inflatable structures, and energy harvesting technologies, may have potential advantages to realize miniaturized and affordable design of GPS buoys. In this paper, a smart structure-based design of an ocean wave energy harvester for a GPS buoy is studied. A plucking harvester, a highly efficient energy harvesting device suitable for low-frequency and large stroke applications, is particularly investigated in terms of the maximization of its energy density.

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In the present paper, phase-shifted voltage was applied to discrete electrodes of PZT bimorph actuator in order to derive pseudo-wave deformation. The behavior of deformation of the actuator was calculated by the 3-D FEM piezoelectric analysis. In the model dimensions, thickness was 0.7mm and the wavelength of the deformation wave was 30mm. The AC Voltage of 200V amplitude was applied to the parallel-type bimorph actuator. From the calculated results, it appeared that amplitude of the wave deformation along center was maximum and that along the free-edge was minimum. It was also shown that the curvature in the width direction decreased when width increased. From these results, wide-width design was necessary for manufacturing high-performance actuators.

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A capsule-type micro actuator using hydrogen storage alloys (HSA-CMA) mounted on the super multi-link manipulator to capture space debris was developed as a compact, lightweight and energy saving actuator. The HSA-CMA drives by the volume change of hydrogen storage alloy induced by its hydrogen absorption and discharge. In this paper, the HSA-CMA with 10 mm diameter using palladium as hydrogen storage alloy, which has the high activity with hydrogen. Hydrogen gas was introduced into and evacuated from the sample in the vessel and its height change was measured. The obtained deformation were 25 μm after 5000 s of the hydrogen introduction and 21 μm after 14000 s of the following evacuation. From the results, it was confirmed that this actuator drove at room temperature and with low hydrogen pressure, and that it had the deformation ratio comparable to that of a piezoactuator.

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The purpose of this study is to application of camera posture aid using Ti-Ni superelasticitc alloy. The composition of this alloy is Ti-50.8at%Ni. This alloy showed the superelastic behavior at room temperature. The maximum load of superelastic wire is 11N by three point of bending test. The superelastic component of camera posture aid was made from sixteen Ti-Ni wires of 1.0mm in diameter and 170mm in length. The camera posture aid has a part and the part of the prop to attach to an arm. The component arranged on the arm part and prop part. The arm part was made with 3D printer. The weight of camera posture aid is 200g. Mechanical property of the component was using a load cell, Tokyo Sokki kenkyujo TCLZ-5KNA and strain gage, KYOWA ELECTRONIC INSTRUMANTS. The maximum load of the camera posture aid is 7N. The camera shake was reduced about 65.5% by camera posture aid.

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In order to understand the transformation characteristics of Ti Ni shape memory alloys, it is crucial to know its fundamental atomic structure. While many sources have provided detailed explanations about the basic theory of martensitic transformations, it is hard for engineers who do not have expertise in metallurgy to understand the crystal structures because they are illustrated in terms of unit cells in two-dimensional figures. When it comes to lattice correspondence in Bain deformation, which is one of the transformation characteristics, the explanation can be even more complex. Without three-dimensional illustrations of crystal structures, explanations about lattice invariant shear were extremely hard to understand for such engineers. Therefore, changing the viewpoint of conventional ways of the explanation, this paper illustrates a crystal structure in the parent B2 phase as a single unit cell (because Ti and Ni have the same number of atoms) in a method that incorporates Miller indices and Trigonometry projection used in mechanical drawings. This paper also illustrates atomic structures of the parent phases and martensite in three-dimensions to describe the process of martensite transformations (Bain deformation) and two types of atoms in each crystal structure of transformation using different colors.

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This study is about damage identification of electric point machine using Bayesian estimation. The electric point machine is equipment for change the direction of movement of the train. Since the fault of the machine may cause long time closure of traffic, it automatic early detection and identification system is important for early recovery. In this paper, effect of positive probability of error due to temperature change is evaluated.

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We used a Kriging model to visualize the uncertainty of the estimated damage location from time domain reflectometry (TDR) measurements. The damage can be clearly detected on the transmission line through the application of a 2D microstrip line differential circuit for TDR. The reflection voltages between the observed points are interpolated, and the uncertainty is obtained by Kriging. We integrated the estimation and uncertainty contour maps into a single figure for easier understanding and statistical quantification. We used the measured TDR data to investigate three types of visualization models for damage inspection: hue-saturation-intensity color, crack existence probability, and expected improvement. All three methods quantitatively visualize the estimated crack configuration with uncertainty in a single figure. By operating these visualization models depending on the inspector's preferences, more appropriate crack estimation can be performed for wide-area fast scan-type inspections such as TDR. In particular, the latter two models can be directly used as an evaluation index for secondary inspection.

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The system detecting crack on tunnel wall selectively by vehicle passing in tunnel has been proposed. That system consists of mechanoluminescence and TDI camera. In this paper, we report about the quantification of mechanoluminescence of crack due to pressure change, and the applicability of TDI camera to detecting mechanoluminescence of crack. Firstly, selective mechanoluminescence on crack due to pressure change is demonstrated. Experimental setup includes cylinder piston compressing enclosed space and test plate with simulated crack placed at bottom face of enclosed space. The surface of test plate with simulated crack is coated by mechanoluminescence particles. When a pressure change of 3.5 kPa occurs in enclosed space, the surface of test plate produces luminescence along the crack shape and luminescence value is 6 gray digits by CCD camera. Thus, mechanoluminescence of crack shape by pressure change is demonstrated. Secondly, detection of weak luminescence during moving is demonstrated. Experimental setup includes the rotating circular plate with luminous target on outer side. When the outer circumference rotates in 300 km/h, the target that luminescence value sets 6 gray digits corresponded by CCD camera is not detected by TDI camera. When the luminescence value is set to 300 times of 6 gray digits, it is detected by TDI camera. Thus, detection of mechanoluminescence of crack in 300 km/h movement by TDI camera is possible, if the strength of mechanoluminescence or sensitivity of TDI camera is enhanced by 300 times.

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This paper describes the development of the correction system for multi-spectral image inclination on a small-type unmanned aerial vehicle; the correction system was demonstrated. The present system performed the attitude control of vehicle on the computation for its easy operation using State Regulator Control. The results indicate that the limitation of feasibility for control on the present system; the next assignments can be revealed. The cause that a vehicle becomes unstable has been revealed in the equations of motion.

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In the present paper, we developed measurement system of degree-of cure of FRP laminates using optical fiber sensors with bending-loss compensation. Two SLD light sources whose center wavelengths are 1310nm and 1550nm were used. The combined sensor of a Fresnel-based refractive-index sensor and an FBG sensor were employed for measuring degree-of-cure and strain. The optical intensity measured by the 1310nm light was compensated by the optical loss of the 1550nm light. The experimental results showed that the optical loss of the 1310nm light by local bending was compensated successfully by the proposed method.

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For practical uses of self-sensing Carbon Fiber Reinforced Plastics (CFRP) based on the electrical conductivity of carbon fiber, electrical contact between electrodes and carbon fiber is one of the most important issues. This is because the residual resin between electrode and CFRP laminate improperly affects the measured value of electrical resistance change of CFRP laminate. In addition, the simplicity of the manufacturing process of electrodes is strongly required. In the conventional manufacturing process of the copper plating electrodes at a test piece level, surface condition after removing surface resin of CFRP laminate by sandpaper depends on individual manufacturers. In the present study, the newly invented method to remove surface resin by CO_2 laser treatment is proposed. Some experiments with various combinations between laser power and processing speed were performed; the measurement of electrical contact resistance by the Transmission Line Measurement (TLM) method and the probe method, the microscopy of the laser treated area and the evaluation of electrical contact resistance increases after cyclic loading test. As a result, the feasibility of the proposed method was shown.

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cBN-particle-dispersed-aluminum (Al) matrix composites were fabricated in solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of cBN powders, Al powders and Al-5 mass%Si powders. The microstructures and thermal conductivities of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 798 K and 876 K for 1.56 ks during SPS process. No reaction at the interface between the cBN particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the Al/cBN composite fabricated at a pressure of 300 MPa was higher than 99% in a volume fraction range of cBN between 35 % and 50 %. Thermal conductivity of the Al/cBN composite increased with increasing the cBN content in the composite in a volume fraction range between 35 and 45vol%. The highest thermal conductivity was obtained for Al-45 vol%cBN composite and reached 305 W/mK.

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The developments of Cu-based MoS_2-dispersed composite materials to be used in high vacuum have been attempted. In conventional powder metallurgy techniques, Cu/MoS_2 loses its friction property by generating compounds due to the heating process even in inert gas atmosphere. In contrast, Cu/MoS_2 can be formed by a novel powder molding technique, compression shearing method at room temperature (COSME-RT) without heating. In the previous study, it was clarified that mechanical properties of Cu/MoS_2 were decreased while friction coefficient were decreased with increasing MoS_2 concentration. To improve the friction property of Cu/MoS_2 while maintaining its material strength, this study focuses on the difference between microstructures of two surfaces of a Cu/MoS_2 thin plate formed by COSME-RT. The microstructures and friction properties of these two surfaces were investigated. It is clarified that there is a difference in MoS_2 dispersions of two surfaces. One surface which has less aggregation of MoS_2 shows lower friction coefficient than the other. It is less than 0.1.

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The thermoelectric power generation device can take out electric energy from thermal energy directly. In order to transform a difference of temperature into electric power efficiently, it is common to make the thermoelement of N-type and P-type into pi structure. Since the thermoelectric power of an element was small, much pi structures needed to be connected with series, but when a large number were connected with series, there was a problem that internal resistance will become large. In this study, we propose a new stacked π-type structure sandwiched between an insulating layer using a metal direct bonding technology. By using this technique, significantly lowered layered structure the electrical resistance of the joint portion, because it can be produced by laminating at least one hundred sheets at a time, even when using a metal material having low Seebeck effect, a sufficiently practical level It can boost the voltage, a possible cost reduction of the device itself. Further, since the laminated π type structure fabricated Each interface is tightly bonded by eutectic reaction, it is possible to use a structure having a power generation function.

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In this study, a fabrication method of a CFRP using novolak phenolic resin as a matrix and its mechanical properties were reported. CFRP, A CFRP prepreg was developed by using the solution of novolak resin and acetone (PA solution). The PA solution was fully impregnated with carbon fibers by conventional pultrusion techniques because of its low viscosity. After drying of acetone included in the PA solution, the CFRP prepreg with high volume fraction of carbon fibers was obtained. By using this CFRP prepreg, the unidirectional CFRP plate with 1 mm thickness was fabricated with hot press method. The bending properties of novolak CFRP were larger than those of CFRP composed of the same carbon roving and the resole phenolic resin.

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This study aimed to predict the optimum processing condition for thermoplastic tape laying. The material used for the experiment was unidirectional carbon fiber reinforced polyamide 6 (CF/PA6) prepreg tape. The effects of processing conditions such as output of infrared heater, feed speed of tape, temperature and pressure of compaction roller on the laying behavior of prepreg tape were investigated. The experimental results revealed that the surface temperature of CF/PA6 prepreg tape and singe lap tensile strength tends to increase with decreasing the feed speed of prepreg tapes.

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This paper presents experimental results for fracture behavior of injection-molded glass fiber/polyamide 66 composites. A weighed amount of glass fibers was mixed with polyamide 66 using a twin extruder and the amount of glass fibers was varied from 17 to 41 vol%. Three point bending tests were carried out on single-edge notched bend (SENB) specimens. Specimens were prepared by cutting injection-molded plates in three different directions: parallel to the flow direction (0-SENB specimens), normal to the flow direction (90-SENB specimens), and 45° to the flow direction (45-SENB specimens). The effects of the specimen orientation and fiber volume fraction on the fracture behavior were investigated. In addition, the microstructure of the fracture surfaces of the composites was examined by a scanning electron microscope (SEM). The strain energy at the maximum load for the SENB specimens remained nearly constant at the fiber volume fraction was increased.

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In this study, we made polylactic acid-base green composites reinforced with short Manila hemp fiber, and evaluated their thermal property and moisture absorbing and desorption behavior. It was found that the thermal conductivity of randomly-oriented short fiber composites also showed a similar dependence on the lumen size in the fiber as that of unidirectional composites. Malila hemp fiber has a good humidity control ability, and thus the green composites reinforced by this Manila hemp fiber also show a similar functionality, namely humidity control ability.

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This study aims to develop the hybrid injection molding method combined with hot pressing for mass production of continuous carbon fiber reinforced thermoplastic (cFRTP) parts. A new type of heating system for hybrid injection molding was originally developed using near-infrared light and its linear drive carrier. The trial sample was a V-shape box type of shock absorber with light and high stiffness. The material used for skin layer was woven carbon fabric reinforced thermoplastic (woven-CF/PA66) laminate, which was formed by mold clamping process immediately after heating with near-infrared light inserted in die set. After the forming step, a short carbon fiber reinforced thermoplastics (short CF/PA66) was injection molded to form the grid-shaped rib-structure from within V-shape member. The 3D shape measurement of molded parts was evaluated by a digital image measurement robot system. The results shown the fusion bonding between woven CF/PA66 laminate formed thermally and short CF/PA66 injection-molded was significantly affected by heating time of woven CF/PA66 laminate, while the surface of skin layer was also thermally-deteriorated by overheating. Thus the heating conditions should be optimized to be satisfied the both fusion bonding strength and the surface quality.

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We estimate effects of ply thickness on mechanical properties and damage evolution of CFRP angle-ply laminates under various tensile loading. It should be noted that the laminate thickness is almost the same, but the ply thickness are quite different. Monotonic tensile tests, cyclic loading-unloading tensile tests and stress relaxation tensile tests are performed on [(±θ)_<12>]_s (t-0.05 prepreg×48plies, t-0.05 ply thickness), [(±θ)_4]_s (t-0.15 prepreg×16plies, t-0.15 ply thickness) and [(+θ)_4/(-θ)_4]_s (t-0.15prepreg× 16plies, t-0.6 ply thickness) T700SC/2500 carbon/epoxy laminates with various fiber directions (θ=30, 40, 45, 50 and 67.5°) at 1.0 mm/min crosshead speed. Laminates with thin ply thickness showed high strength and fracture strain. From SEM observation, t-0.6 laminates exhibit brittle fracture, however delamination occurred in each interlaminar interface in thin ply thickness (t-0.05, t-0.15) laminates. In stress relaxation tests, laminates exhibit nonlinear response and then stress relaxation behavior appears. In addition, it is considered that each angle-ply laminate have rate dependence in comparison with monotonic tensile test results at 0.1mm/min crosshead speed. Also damage evolution can be determined by cyclic loading-unloading tensile tests. We use mesoscale damage model to investigate damage evolution in CFRP laminates. From damage observation and damage evolution analysis, it is considered that thin ply thickness laminate can accumulate damage in specimen until high stress state.

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