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Kohei KAKU, Yusuke Fushimi, Masahiro ARAI
Article type: Article
Session ID: 1224
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In the present paper, thermo-viscoelastic constitutive equation of carbon fiber reinforced plastic is investigated by numerical approach based on finite element method(FEM) and homogenization theory. The constitutive equation of the CFRP is considered on the Laplace-transformed domain, and it is discussed based on correspondence principle which is satisfied by the each Laplace-transformed elastic moduli. Homogenization theory is employed to estimate the 'homogenized elastic moduli' of the composite composed of matrix resin and carbon fibers. Using approximation of generalized Maxwell model, the relaxation modulus of CFRP is obtained by numerical computation with FEM. The effect of the volumetric loading rate of the carbon fiber and the individual elastic moduli of the fiber and matrix on the estimated relaxation moduli are discussed from the results of numerical demonstration in detail.
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Masayoshi SHIMIZU, Takahito GOSHIMA, Masahiro ARAI, Kenta SUZUKI, Kous ...
Article type: Article
Session ID: 1225
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this study, analysis of residual stress and deformation in CFRP which is anisotropic thermoviscoelasticity is discussed. The analysis is calculated, according to thermoviscoelastic theory which is based on time-temperature superposition, and using Laplace transformation for 2-dimensional and 3-dimensional BEM. Thermoviscoelastic model is approximated by Maxwell model.
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Masahiro ARAI, Kazutoshi MATSUSHITA, Satoshi HIROTA
Article type: Article
Session ID: 1226
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In the present paper, criterion of interlaminar strength for unidirectional CFRP laminates was discussed. Generally, interlaminar shear strength (ILSS) of the CFRP laminates is evaluated by 3-point bending test, but the criterion of the fracture depends on not only interlaminar shear stress but also interlaminar normal stress in the specimens. In order to obtain the limit curve which is given by the relation between normal stress and shear stress, two types of ILSS test have been employed in the present study. The one is a 'compression type ILSS test' by a simple 3-point bending. The another one is a 'tension type ILSS test' applying the shear tensile loading using a shear pin. Employing 2-dimensional finite element analysis the criterion of the CFRP laminates and CFRP toughened by carbon nanofiber were investigated in detail using a modified 'Tsai-Wu' criterion.
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Yu ITO, Keiichiro TOHGO, Yoshinobu SHIMAMURA
Article type: Article
Session ID: 1227
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper deals with a micromechanics model of particle-reinforced composites which can describe the debonding damage of particles from matrix, matrix plasticity and particle size effect on deformation and damage. Tohgo-Chou-Weng's incremental damage theory of particle-reinforced composites based on the Eshelby's equivalent inclusion method and Mori-Tanaka's mean field concept has been extended to consider the particle size effect by using Nan-Clarke's simple method. Numerical analyses are carried out on a SiC particle reinforced aluminum alloy composite (SiC/A356-T4) containing particles with size distribution under uniaxial tension. We compared our analytical results with the Lloyd's experimental results, and it is found that the experimental stress-strain relation of the SiC/A356-T4 can be described by the present model taking account of the particle size effect, particle size distribution and debonding damage.
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Kenta Hamada, Tetsusei KURASHIKI, Masaru ZAKO, Hiroaki NAKAI
Article type: Article
Session ID: 1228
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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It is difficult to predict mechanical characteristics of stitched UD laminates because of their complicated geometrical shapes caused by stitching yarn and opening resin region, etc. In order to solve the difficulty, we have developed the automatic FE modeling system, and estimated the mechanical characteristics of stitched UD laminates. In the developed system, geometrical models are generated with WiseTex program, and FE models are created with MeshTex program. Stitching yarn and plies with opening resin region are modeled individually, and the stress distribution is estimated with both models by mesh superimposed method.
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Yuzo Fujita, Testusei Kurashiki, Hiroaki Nakai, Masaru Zako
Article type: Article
Session ID: 1229
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An estimation method for mechanical properties of fiber reinforced plastic considering an uncertain microstructure has been described in the paper. As fabric composites are basically made of fiber bundles which can be treated as unidirectional FRP, the mechanical characterization of unidirectional FRP is very important to characterize fabric composites. Since the filaments in the fiber bundles are arrayed randomly, we have generated several FEM models of unidirectional FRP considering the uncertain arrangement of filaments, and estimated the mechanical properties such as stiffness and strength. As the numerical result, the mechanical properties, especially transverse strength has dispersed largely. In addition, the strength decreases caused by residual thermal stresses.
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Shunsuke MIYAGAWA, Masaki OMIYA
Article type: Article
Session ID: 1230
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Porous low-k dielectrics are introduced for low-k dielectrics because of its ultra low-k dielectric constant. However, their poor mechanical strength and high coefficient of thermal expansion can cause cohesive failure of low-k dielectrics or interfacial failure between Cu/low-k dielectrics during thermal cycling or CMP(Chemical Mechanical Polishing) process. Especially, the damascene structure of the Cu interconnect can give rise to complex stress states and this causes a lot of issues during the fabrication process. Therefore, it is important to study the relationships between the porosity and the mechanical properties and, also, the porosity and the dielectric constant. In this paper, we studied the effect of the porosity in low-k dielectric film between copper wirings on the dielectric constant and the stiffness by numerical simulation. The effects of the shape and the porosity of pores in low-k dielectric film on the mechanical properties and the dielectric constant were discussed.
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Tomohiro YAMANAKA, Tomoyasu AIHARA
Article type: Article
Session ID: 1231
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Molecular dynamics computer simulation was performed for model polyethylene polymer under heating and/or cooling condition. Polyethylene melt become amorphous structure under glass transition temperature T_g=240.3K. End-to-end distance between carbon atoms in polyethylene molecule is not normally distributed under T_g. Internal energy of the system depends on elastic strain. Proportional constant on term of square of strain gives elastic stiffnesses. Simulated Young's modulus of the amorphous polyethylene is 84.7GPa at 100K.
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Go MURASAWA, Kazuhiro KITAMURA, Satoru YONEYAMA, Shuichi MIYAZAKI, Ken ...
Article type: Article
Session ID: 1232
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Shogo KOBAYASHI, Satoshi TOMITA, Hironori YAMASHITA, Shigetoshi ARAKI, ...
Article type: Article
Session ID: 1233
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Micromechanical analysis is performed on a Al composite material containing many elliptic magnetite reinforcements by using the equivalent inclusion method combined with the Mori-Tanaka theorem. Both the macroscopic electrical conductivity and the macroscopic magnetic permeability of the composite can be successfully expressed as a function of the aspect ratio of inclusion and their changes in values can be estimated numerically with respect to the aspect ratio of reinforcement. It can be see from the numerical results that the optimal shape of the reinforcement may exist for the maximum increase in the magnetic permeability and the minimum decrease in the electrical conductivity.
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Fumio NARITA, Yasuhide SHINDO
Article type: Article
Session ID: 1234
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper studies the activity and sensitivity of functionally graded piezoelectric cantilever transducers under electromechanical loading through numerical and experimental characterizations. A phenomenological model of domain wall motion in alternating current (AC) electric fields is used, and a nonlinear three-dimensional finite element method is employed to simulate the dynamic response of functionally graded piezoelectric cantilever transducers. The effects of AC electric field amplitude and frequency, number of layers, and property gradation on the output voltage, deflection and internal stresses of the transducers are examined. Experimental results, which verify the model, are also presented using functionally graded piezoelectric bimorphs.
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Gakuji NAGAI
Article type: Article
Session ID: 1235
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We propose a numerical procedure for nonlinear electromechanical problems in smart ceramics. Two essential features of the present procedure are the use of a Landau's phenomenological potential energy as nonlinear constitutive law and the finite element discretization of an alternative governing equation with vector potential. For solving the resulting semi-discrete nonlinear system, the Newmark-β method is employed. Numerical examples in two dimensions are shown to validate the present procedure.
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Tetsuya HATA, Hiroyuki KURAMAE, Kazuyoshi TSUCHIYA, Yasutomo UETSUJI
Article type: Article
Session ID: 1236
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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External load turns the orientations of spontaneous polarization in microscopic domain structures of piezoelectric materials. This domain switching in microscopic structure dominates macroscopic piezoelectric performance. This paper presents a multiscale nonlinear finite element method through a crystallographic homogenization method to analyze ferroelectric hysteresis behaviors caused by domain switching. As a computational example, the electric field-strain relations were discussed for BaTiO_3 single crystal with various initial orientations.
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Yasuhito FUKUTA, Kazuyoshi TSUCHIYA, Yasutomo UETSUJI
Article type: Article
Session ID: 1237
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this study, we challenged to derive new bio-compatible piezoelectric materials in perovskite-type oxide ABO_3 through first-principles calculation. Firstly, stable combinations which satisfy the geometric stable and the coordination number condition were searched. Then, phonon properties in cubic structures were analyzed and the possibilities of structural phase transition from cubic structure to tetragonal one were explored for the promising materials. As a result, we discovered CaTiO_3 and CaZrO_3 for the bio-compatible piezoelectric material.
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M. Fukumoto, H. Terada, K. Sato, M. Mashiko, M. Yamada, E. Yamaguchi
Article type: Article
Session ID: 1238
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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To improve the deposition efficiency of 5 μm Cu particle onto metallic substrate by cold spray, optimization in nozzle design was performed by numerical simulation. In the spraying of copper particle onto normal steel substrate, unique lamellar-like microstructure was formed near the interface region in the steel substrate. To reduce the bow shock effect on the substrate surface region in cold spray process, special nozzle was newly designed. The deposition efficiency, Vickers hardness and coating adhesion strength increased significantly especially in the case of fine particle and higher pressure level of the working gas, while nominal particle velocity decreased with the special nozzle. Numerical simulation indicated that the pressure levels on the substrate surface decreased effectively in the nozzle newly designed. The results indicate that the decrease of particles velocity due to bow shock was suppressed effectively in the special nozzle as compared with conventional one.
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Koichi TAKADA, Kazuhiko SAKAKI, Muneaki TAKAHATA, Kazuya TAKEDA, Yasuo ...
Article type: Article
Session ID: 1239
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to improve the coating properties, nozzle geometry influences gas dynamics making sprayed particle behavior is important parameters. Gas flow at the entrance of the convergent section of the nozzle takes place at relatively high temperature and at subsonic speeds. Thus, this region is a very suitable environment for heating the spray particles. As already reported, it has shown that the improvement of the adhesion strength and deposition efficiency of copper coating by extension of the convergent length of nozzle. In this study, experiment was conducted to investigate the effect of convergent section length of nozzle on adhesion morphology and deposition ratio of individual copper particles. Used nozzles have variety length of convergent section. The result shows that deposition ratio and flattening ratio of individual copper particles on steel substrate gradually increase along with extension of the convergent section length of nozzle.
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Kota SAITO, Kazuhiko SAKAKI, Kazuya TAKEDA, Kouichi TAKADA, Sou NAKAGO ...
Article type: Article
Session ID: 1240
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The actual mechanism by which the solid particles deform and bond duffing cold spray is still not well understood. For example, High-strength brass powder was little deposited in spite of low melting temperature. In this study, it was aimed to clear the deposition behavior with investigation of critical velocity with numerical simulation and observation of an individual particle. Although deposition efficiency is different, copper: 80%, 60/40 brass: 60% and High-strength brass: almost 0%, critical velocity is almost equal. High-strength brass powder were done brittle fracture. From these results obtained, it seemed that low deposit efficiency cause of brittle β-phase.
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Satoshi AMAO, Yuji ICHIKAWA, Kazuhiro OGAWA, Tetsuo SHOJI, Hirotaka FU ...
Article type: Article
Session ID: 1241
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Carbon steels have been using in many structures, because the steels have excellent workability, affordability, and low price etc. However, it can be obtained corrosion damage or cracking on aging degradation. Cold spraying, which is a new maintenance technology, attracts attention recently. Though, it's difficult to make high carbon steel coatings by cold spraying, because high carbon steel includes much carbon. As a result, these are not many studies of cold sprayed carbon steels. In this study, dense and thick coatings of carbon steels by cold spraying was obtained, High carbon steel powder and mixed powder, which is mixed high carbon steel with mild steel powder were used. As a result, denser carbon steel coatings were obtained. And also, the coating hardness was higher than that of bulk steels.
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Kazuhisa SATO, Tatsuya SONE, Keiji YASHIRO, Kazuhiro OGAWA, Tatsuya KA ...
Article type: Article
Session ID: 1242
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Powder Jet Deposition (PJD) method is one of the film forming technique& Ceramics films can be fabricated by this method Ytariastabilized zirconia (YSZ) thin films were deposited on various substrates by PJD method YSZ thin film was fabricated in systemically changed substrates, particle sizes and carrier gas pressures. The microstructures of YSZ films were observed by scanning electron microscope (SEM). From this study results, the amount of deposition rate by PJD method varies according to substrate hardness and powder size. Similarly, the film structures are affected by substrate and powder size. Additionally, the electrical conductivity of YSZ film on Al_2O_3 substrate was measured as a function of temperature using impedance and two-probe A.C. method From this measurement, the amount of this film's electrical conductivity is good agreement from other studies of YSZ bulks. This result shows probability of application to high temperature ceramics devices such as Solid Oxide Fuel Cells (SOFCs), gas sensors.
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Satoshi YAMAGISHI, Shin-nosuke YAMADA, Masato DEZAKI, Masakazu OKAZAKI ...
Article type: Article
Session ID: 1243
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Indentation test was carried out to measure mechanical properties (especially elastic modulus) of 8 wt.% Y_2O_3 partially stabilized ZrO_2 (YSZ) top coat used for Thermal barrier coatings (TBCs). The top coat was fabricated by air plasma spraying (APS) method. The APS coatings have very characteristic microstructure that consists of ceramic splats and inter-splat pores. Focusing on the intrinsic splat-structure on the mechanical behavior of APSed YSZ TBCs, quasi-splat structure specimens were also specified for the comparison. Special discussions were made on the effect of inter-splat pore on the elastic modulus evaluated by the indentation method.
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Yasuhiro YAMAZAKI, Toshihiko YOSHIDA, Hirotaka FUKANUMA, Naoyuki OHNO
Article type: Article
Session ID: 1244
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The effect of the bond-coating on the adhesion strength after the thermal fatigue test was investigated in the air plasma sprayed thermal barrier coatings (APSed TBCs). In this work, two kinds of the CoNiCrAlY powder with the different particle size were used for spraying the bond coating material. In addition, the bond coat was sprayed by either the low-pressure plasma spray (LPPS) method or the high velocity oxy-fuel (HVOF) one. The adhesion strength and the residual stress were evaluated as a function of the thermal fatigue cycles. The experimental results indicated that the adhesion strength after thermal cycle fatigue was varied with the bond-coating. The effects of the residual stress and the thermal fatigue damage, i.e., micro-cracks, on the adhesion strength were discussed.
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Shouichi INABA, Masao KOUZAKI
Article type: Article
Session ID: 1245
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this work, we attempt to improve the performance of cutting tools against titanium alloy by coating of titanium-boron-carbon (Ti-B-C) thin films. We have prepared the Ti-B-C thin films by DC magnetron sputtering using boron carbide (B_4C) target and Ti target. And we have used silicon plates for the deposition experiments. The target power for Ti was varied from 0 to 200Wand CH_4 gas flow rate from 0 to 80 socm in the deposition process to understand the influences of titanium and carbon contents on nano-indentation hardness, frictional properties and adhesive strength of coatings. As a result, when the target power for Ti was increased, adhesive strength of coatings is risen. And when CH_4 gas flow rate is 40 socm, frictional properties are decreasing.
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Naohiro NISHIKAWA, Shinnosuke Sato, Toshirou IYAMA, Masahiro MIZUNO, H ...
Article type: Article
Session ID: 1246
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This investigation has aimed to achieve micro machining cheaply and easily by using the method of electroplating. The precise three-dimensional processing is performed on a workpiece with electrode which is used in electroplating. The workpiece and the probe type electrode are put in electrobath as an electrode and it supplies an electric current. A deposit is made on the surface locally when workpiece becomes the cathode. If a thin probe type electrode is used to it, the processing becomes more fine. The experimental equipment is that the probe type electrode installed on piling up X-table, Y table, and Z-table controlled by micro screw and stepping motor. In an experiment, local deposit was confirmed, and deposit line was formed by probe type electrode scanning. The deposit profile appeared the belllike shape. The height of a deposit measured by roughness meter in probe electrode each scan cycle and scanspeed.
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Syunsuke SUDO, Koji TAKAHASHI, Kotoji ANDO, Sinji SAITO
Article type: Article
Session ID: 1301
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The crack-healing behavior under compressive stress of Si_3N_4/SiC Composite was investigated. Effect of compressive stress on strength recovery by crack-healing at 1000℃ for 5 h in air was studied. A semi-elliptical surface crack about 100pm in diameter was introduced on the center of specimen. Followings are main conclusions obtained; (1) Under compressive stress, the strength of pre-crack specimens increased by crack-healing. (2)The pre-crack was healed, and the strength recovered under tensile stress and no stress. (3) Under 400MPa of tensile stress, specimens fractured before healing. But under 400MPa of compressive stress, specimens healed a crack. Therefore, it was found that crack-healing is effective not only under tensile stress but also under compressive stress.
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Toshio OSADA, Wataru NAKAO, Koji TAKAHASHI, Kotoji ANDO, Shinji SAITO
Article type: Article
Session ID: 1302
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Effect of partial oxygen pressure on crack-healing behavior of alumina/SiC particles composite was investigated. A semi-elliptical crack with surface length of approximately 100 p.m was introduced by Vickers indentation. The specimens were heat-treated under various crack-healing conditions using tube furnace with gas flowing system. Complete strength recoveries were attained by crack-healing in low oxygen pressure of 5×10^3 and 50 Pa at optimized condition. The optimized conditions of crack-healing in 5×10^3 Pa and 50 Pa were heating at 1623 K for 1 h and 1673 K for 10 h, respectively. However, strength recovery rate by crack-healing decrease with decreasing partial oxygen pressure. From the result, it was concluded that crack could be completely healed under low partial oxygen pressure.
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Young-Soon JUNG, Wataru NAKAO, Koji TAKAHASHI, Kotoji ANDO, Sinji SAIT ...
Article type: Article
Session ID: 1303
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The crack-healing behavior of Si_3N_4/20 wt% SiC composite sintered with 8 wt.% Y_2O_3 was investigated under low oxygen partial pressure (pO_2=50, 5000, 21000Pa). A semi-elliptical surface crack with length of about 100 μm was introduced on the tensile surface by Vickers indentation. The specimens were healed at various conditions using the tube furnace with gas flowing system. After crack-healing, the bending strengths were tested at room temperature and at high temperatures ranging 800℃ to 1400℃. Even under pO_2=50Pa, the crack was completely healed at 1300℃ for 10h heat-treatment. Also, the high-temperature strength of crack-healed specimens at pO_2=50Pa showed almost constant bending strength of about 900MPa up to 1400℃.
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Keisuke IWATA, Yoshitake NISHI
Article type: Article
Session ID: 1304
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Effects of electron beam irradiation on the fracture resistance of glassy ceramics were studied. EB-irradiation could not change the resistance to crack propagation, which was estimated by fracture toughness evaluated by means of standard indentation fracture method. On the other hand, EB irradiation increased the plastic deformation energy to generate the crack. In addition, if EB-irradiation formed dangling bonds in glassy network structure, they probably relax the residual stress and should prevent the crack generation. As the results of electron spin resonance spectra, the EB irradiation generates dangling bonds in these glasses, partial relaxation of residual strain mainly occurs around dangling bonds in the network structure. The increasing the generation energy of crack was therefore mainly due to the relaxation of the strong bonded metal -oxygen atomic pairs in network structure, as well as annihilation of crack origin.
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Hiroshi ASANUMA, Tatsushi KAIHO, Jun KUNIKATA
Article type: Article
Session ID: 1305
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper presents the development of a new optical fiber connector formed in an aluminum matrix. In the previous study, an optical fiber sensor was successfully embedded in an aluminum matrix by the Interphase Forming/Bonding Method. However, there is a problem of the robustness of the connecting points because the optical fiber gets brittle in the high temperature embedding process. Connection of the optical fiber is not easy if it is broken near the edge of the optical fiber/aluminum composite. So in this study, formation of the new optical fiber connector in the aluminum matrix was investigated, and the connector was successfully made in it by embedding a notched optical fiber and pulling it out of the matrix.
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Tatsuro KOSAKA, Shota YAMAMORI, Katsuhiko OSAKA, Yoshihiro SAWADA
Article type: Article
Session ID: 1306
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We have developed fiber optic strain and vibration sensors (FOSVS) suited for health monitoring of structures. A fiber optic gap sensor made of multi-mode fibers, broad-band light, two photo detectors and an FBG filter were used to compose the sensor system. The gap sensor was composed of a cantilever fiber and a reflector fiber. The axial strain of the sensor was measured from the reflected interfered signal. The amplitude of the transmitted signal through the reflector fiber was used to measure the transverse vibration of the cantilever fiber. In the present study, the sensors were embedded in epoxy plates and cantilever vibration tests were conducted. From the experimental and theoretical results, it appeared that the embedded FOSVS in specimens could measure dynamic strain and vibration of a vibrating cantilever plate simultaneously. From these results, it can be concluded that the FOSVS sensor has practical capability of simultaneous measurement of internal strain and vibration of materials.
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Hideaki MURAYAMA, Kohei OHARA, Gakuro AKIYAMA, Hirotaka Igawa, Isao Ya ...
Article type: Article
Session ID: 1307
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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We have developed a distributed strain measurement system using fiber Bragg grating (FBG) sensors, based on optical frequency domain reflectometry (OFDR) which can measure strain distributions with a high spatial resolution of less than 1 mm at an arbitrary position along a long gauge FBG. In addition, quasi-distributed measurement is also possible by using multiplexed FBG sensor arrays. In this study, we applied this measurement system to the strain monitoring of a composite wing structure made by vacuum assisted resin transfer molding (VaRTM) during a series of load tests, and evaluated its applicability. We could successfully equip inner and outer skins of the wing box with several long gauge FBG sensors and multiplexed FBG sensor arrays. The measured results by multiplexed FBG sensor arrays showed the overall deformation of the wing box. On the other hand, strain distributions of strain concentration zones were successfully measured by long gauge FBG sensors. Consequently, we can say that we confirmed the applicability of our strain measurement system by OFDR to the monitoring of a full-scale composite structure.
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Naoki HIRAOKA, Ryosuke MATSUZAKI, Akira TODOROKI
Article type: Article
Session ID: 1308
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In order to improve performance of anti lock brake system (ABS) and detect condition of road surface, intelligent tires that monitor strain of interior surface and rolling radius of tire are demanded. However, the high stiffness of an attached sensor like a strain gauge causes debonding of sensors from tire rubber. In the present study, noncontact concurrent monitoring method is proposed using digital image correlation method (DICM) and spotlight projection. In-plane strain and out-of-plane displacement (rolling radius) are calculated by using image processing with an image of interior surface of tire that is taken with a single CCD camera fixed on wheel rim. New monitoring system is applied to Al beam and commercially available radial tire. As a result, this monitoring system is proved to be able to measure in-plane strain and out-of-plane displacement with high accuracy, and confirmed to be effective for concurrent monitoring of tires.
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Ryosuke MATSUZAKI, Akira TODOROKI
Article type: Article
Session ID: 1309
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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From a traffic safety point-of-view, there is an urgent need for intelligent tires equipped with strain sensors as a warning system for road conditions and for optimized braking control on poor road surfaces. However, since a conventional foil strain gage has high stiffness, it causes the analyzed region to behave unnaturally. The present study proposes a novel rubber-based strain sensor fabricated using photolithography. The rubber base has the same mechanical properties as the tire surface; thereby the sensor does not interfere with the tire deformation and can accurately monitor the behavior of the tire. This investigation details the design and manufacture of the rubber-based sensor.
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Yohei TANNO, Hiromi SHIMAZU, Hiroyuki OHTA, Ryuji TAKADA, Takayuki SHI ...
Article type: Article
Session ID: 1310
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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A pin-type load cell with a high-sensitivity semiconductor strain sensor for accurately measuring the load on a machine was developed. To detect shear strain in the pin, two strain sensors were bonded inside it Diffusion layers arranged at 45° to the load direction improve sensitivity to the strain field generated in the pin because they are sensitive in both the longitudinal and perpendicular directions. Performance testing indicated that this pin-type load cell has high linearity and small drift: the nonlinearity was 0.9%, the hysteresis was 1.2%, and the drift of the sensor output was 0.3%.
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Naoto MAKINO, Atsushi IWASAKI, Shinsuke SAKAI, Junji SUGIMOTO, Atsushi ...
Article type: Article
Session ID: 1311
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Monitoring system of railway used by East Japan Railway Company is system to monitor anomaly by sensors on rails and crossing. This monitoring system has a problem. The problem is that the system has many wrong detection. So if anomaly was happened actually, the information would be covered with wrong information. This system needs skillful instruction member because it is hard to judge whether Information is true or not. This delay of judgments may cause more big accident. So it is important to detect true information of anomaly. Therefore we suggest new monitoring system of railway which can detect true information of anomaly from much information including many wrong detection by statistical method.
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Yoshinobu SHIMAMURA, Yuichi HASEBE, Keiichiro TOHGO, Atsushi IWASAKI, ...
Article type: Article
Session ID: 1312
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Satoshi NOMURA, Atsushi IWASAKI, Akira TODOROKI, Yoshinobu SHIMAMURA
Article type: Article
Session ID: 1313
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The SI-F method suggested by Iwasaki et. al, as the reasonable damage detection method This method detected the damage of the structure by using statistical analysis above the con-elation between the sensor outputs. In this method, con-elation between sensor output will be identified by using the response surface method and the similarity of the correlation is tested by using statistical Ftest. In the present paper, the results of experiment for the influence of the sensor position to the accuracy in fatigue damage monitoring of pipe using the SI-F method is shown to validate the optimization of the sensor position.
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Atsushi IWASAKI, Akihiro MORIMOTO, Masataka YATOMI, Tadasi KIMURA
Article type: Article
Session ID: 1314
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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The present study is about an unsupervised damage diagnostic method for the structural health monitoring named as SI-F method. In the proposed method statistically diagnoses structural condition by means of investigating the change of a response surface. The response surface is calculated as a regression model of relationship between multiple sensors. In this method, the change of the response surface is statistically investigated with the F-test. The proposed method doesn't require information about the damaged condition. And the each sensor measurement doesn't need to be same physical quantity an order. In the present study, SI-F method is applied to fatigue monitoring of bridge type specimen. Damage detection using SI-F is conducted from the data measured by the strain gages, the FBGs and the accelerometers. As the result, the origin of the fatigue crack is successfully detected by using arbitrary combination of the sensors.
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Arata MASUDA, Satoshi MAEKAWA
Article type: Article
Session ID: 1315
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this paper, a novel monitoring methodology to detect and characterize damages accompanied by changes in the micro/macroscopic condition of surface contact is proposed. The presented system consists of a PZT patch attached on the structural surface excited by a high frequency harmonic wave. When the structure is subjected to the operational or ambient load at low frequencies, it vibrates, and the inherent damages may introduce a nonlinear effect to the vibro-acoustic dynamics that induces an interaction between the low frequency structural vibration and the high frequency transmitted wave. This nonlinearity is observed as the modulation of the electric impedance of the PZT patch synchronous with the structural vibration. By investigating the relationship between the modulations and the structural vibration, the nonlinear characteristics of the damages can be specified. Experiments using a beam with low-cycle fatigue cracks are conducted for illustrative purpose.
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Yoshimi WATANABE, Satoshi KISHI, Hisashi SATO, Ko MIBU, Satoshi SHIMAK ...
Article type: Article
Session ID: 1316
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In these years, the bag-filter in a dust collector of the waste incinerator is used widely to remove the toxic substance, for example toxic gas, dioxins and heavy metals included in the ash dust by passing through the filter cloth. In order to prevent the destroy of filter, it is necessary to establish the evaluation method of wear for bag-filter. In this study, as investigation of the wear of bag-filter by ash dust, sintered magnetite compact were used for counter material for sliding wear test. The precise amount of magnetite particles embedded into bag-filter was determined by a vibration sample magnetometer (VSM) measurement. It is found that net amount of wear of the bag-filter could be precisely determined by the magnetic measurement. It is also found that the net amount of sliding wear of the bag-filter increases with increasing the wear distance, sliding speed and applied load. To discuss the validity of proposed method, shot peening test with deoxidized iron particles and optical fiber measurement were also carried out for bag-filter sample. The data obtained by the shot peening test and optical fiber measurement are consistent with that obtained by the sliding wear test.
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Seiji KOBAYASHI, Ryosuke MATSUZAKI, Akira TODOROKI
Article type: Article
Session ID: 1317
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Since CFRP structure becomes complicated due to adoption of integral molding, local molding faults such as under cure are liable to occur. For solving this problem, it is demanded to measure the distribution of cure-degree of whole composite structure. In the present study, we propose a patch-type flexible matrix sensor based on permittivity measurements. Multiple electrodes and wirings are readily fabricated at one time using a photolithographic process. Moreover, the sensor has only m+n wirings for m×n sensors, and is thereby suitable for the multipoint measurements. We also constructed the method of estimating degree of cure considering the effect of frequency dependence of permittivity of resin and viscosity variation due to temperature change. Experiment of multipoint cure monitoring are carried out using a CFRP plate. As a result, we confirmed the effectiveness of this method by comparing with the conventional differential scanning calorimeter.
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Yusuke SAMEJIMA, Yoshiyasu HIRANO, Akira TODOROKI, Ryosuke MATSUZAKI
Article type: Article
Session ID: 1318
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In the present study, using the detailed delamination analysis model and Robust Response Surface, the possibility of the delamination identification with the response surface learned from the delamination of different stacking sequence is investigated analytically. It is confirmed that the electrical resistance change distribution depends on only the fiber direction of the surface layer of the specimen. In order to reduce required analytical cost, the identification method, which can solve the inverse problem for various stacking sequences whoes surface layer is the same fibe direction, is proposed. Its applicability is confirmed analytically and the method enable to omit response suface creation for each stacking sequence. As a result, the analytical cost can be reduced.
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Tsutomu ARAKI, Masahito UEDA, Yasuyuki KATO, Akira TODOROKI
Article type: Article
Session ID: 1319
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Since carbon fiber reinforced plastic (CFRP) laminate has superior specific strength and stiffness as compared with metals, it has been increasingly applying to aerospace structures. It is, however, sensitive to an impact which causes a delamination in the laminate. The delamination strongly reduces the mechanical property of the laminate with difficulty of visual inspection. Simple structural health monitoring method is required to maintain the structural reliability of CFRP structures. Many researchers have been reported strain-sensing system of CFRP in which piezoresistivity of CFRP laminate is utilized. It is, however, not reported the delamination sensing. The delamination releases the residual stress in the laminate which was caused in the fabrication process. The delamination may be detected by measuring electric potential changes due to the release of residual stress. In this paper, FEM analyses are performed to investigate the applicability of the method for delamination detection in the quasi-isotropic CFRP laminates.
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Fumihiro NAKAYAMA, Yoji OKABE
Article type: Article
Session ID: 1320
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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In this research, we constructed a wave propagation system consisting of an MFC actuator to generate Lamb waves and an FBG sensor to receive the propagated waves. This system can send and receive broadband ultrasonic waves in CFRP laminates. Hence, we could identify the mode dispersion of Lamb waves propagating in a CFRP quasi-isotropic laminate by sending ultrasonic waves with different frequencies and comparing the result with theoretical dispersion curves. Moreover, we propagated the waves in the laminate with an artificial delamination. As a result, it was found that this system can obtain more effective information for detection of delamination.
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Kensuke SUZUKI, Akira TODOROKI, Yoshihiro MIZUTANI, Ryosuke MATSUZAKI
Article type: Article
Session ID: 1321
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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For Carbon Fiber Reinforced Plastic (CFRP), electrical conductivity of carbon fiber can be used as a sensor for damage detection. The change of electrical resistance of the CFRP structure has been studied as a self-sensing system for monitoring damages. Todoroki et al. reported that the electrical resistance change method successfully monitored various damages like matrix cracking, fiber breakage and delamination in CFRP laminates. There are, however, no reports that the electrical resistance change method successfully monitored compressive fracture of CFRP. Electrical resistance change under compressive load is measured here by three points bending test. The specimen for this was a beam that GFRP is sandwiched between two unidirectional CFRP laminate. As a result, it can be revealed that electrical resistance change shows decrease under elastic area and rapid increase after microbuckling.
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Takeshi NAKAHARA, Takashi FUJIMOTO
Article type: Article
Session ID: 1322
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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Recently smart structures using piezoelectric elements as sensors and actuators of vibration control have been studied. Design and analysis of such smart structure is a multidisciplinary problem that consists of mechanical, electrical and control problem. Therefore, multidisciplinary modeling technique is desired for study of smart structure. However, conventional model of mechanical system is incompatible with model of electrical system. Block diagram can model mechanical and electrical system in generalised form. However physical quantities are treated just as signals and it is not easy to understand physical phenomenon from signal flow in block diagram. Functional model is proposed as a modeling method of multidisciplinary system and can solve the above mentioned problems of conventional models. Functional models of basic elements of mechanical and electrical system, for example, mass, stiffness, capacitor, inductor and DC motor have been developed. However, functional model of piezoelectric element has not been developed. In this paper, functions of piezoelectric element are considered and functional model of piezoelectric element is developed to apply functional model to smart structure system.
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Nagisa Shimazaki, Hiroshi Okubo
Article type: Article
Session ID: 1323
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper investigates the passive vibration suppression system for smart structures using piezo-elements. The vibration suppression system is composed of bimorph piezo-elements (piezoelectric ceramic tiles bonded on the structure) and shunted RL electrical network combined with the piezoelectric ceramics as inherent conductors. The electrical system works as a kind of dynamic damper for the mechanical system. In this paper, the dynamics of the flexible beam with piezo-elements is modeled by using a finite element method, and the performance of the vibration suppression system is evaluated for design parameters such as the location of piezo-elements and the resistance of electrical circuit.
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Nobuyoshi SEKINE, Tokio KITAHARA, Masaaki ICHIKI, Shigeru FUJIMOTO
Article type: Article
Session ID: 1324
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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An electrical generator using piezoelectric element (PZT) is proposed in order to convent diffused vibrations energy. This paper describes the electrical generation characteristics of PZT added dopant (Nb, Fe, Ta, W) the effect of load velocity on static load test. Static load tests are performed using an experimental equipment composed of PZT, oil cylinder and load cell. Static load tests are carried out under the condition of compressive load acting on PZT. Effects of stress velocity, concentration of dopant and kind of dopant on generated voltage and electric power are evaluated.
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Tetsuro YANASEKO, Hiroshi ASANUMA, Takamitsu CHIBA, Jun KUNIKATA, Hiro ...
Article type: Article
Session ID: 1325
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describes the output voltage characteristics of the metal core piezoelectric ceramic fiber/aluminum composite. In this study, the thin patch type device developed by Interphase Forming/Bonding Method in the previous study was evaluated by the oscillation test. As the result, the output voltage from the device was proportional to its strain, independent of its strain rate and changed with its strain direction. In addition, it was also cleared that the phase difference between the output voltage and the displacement of the oscillation plate was changed at a certain strain direction by the difference between the longitudinal piezoelectric constant and the transverse one.
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Hiroshi ASANUMA, Takamitsu CHIBA, Tetsuro YANASEKO, Jun KUNIKATA, Naoh ...
Article type: Article
Session ID: 1326
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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This paper describes the development of the metal core piezoelectric ceramic fiber/aluminum composites using the low cost hollow fibers. In this study, the new fabrication process to fill the Al-Cu liquid phase alloy produced during the interphase forming/bonding method in the hollows was applied to obtain the composites. In order to increase the filling rate as well as removing the voids and the excessive Al-Cu alloy remained in the matrix, the effects of the hot pressing temperature and the pressure were optimized in the experimental ranges. Under the hot pressing temperature of 873 K and pressure of 2.2 MPa, the filling rate attained 96 % without harmful chemical reaction between the fiber and the matrix as well as successful removal of the voids.
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Yasubumi FURUYA, Naoki HOSOKAWA, Yoshiyuki HAYASHI, Masanori YOKOYAMA, ...
Article type: Article
Session ID: 1327
Published: August 02, 2008
Released on J-STAGE: August 01, 2017
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As a first step toward safety monitoring system for environmental condition and mechanical damage of infrastructures with active and embedded nondestructive evaluation module etc. a multi-functional SAW (surface acoustic wave) sensor device was developed especially for hydrogen concentration measurement in the hydrogen melted solution. On the surface part between IDTs, environmentally active material films of two kinds of hydrogen storage alloys were sputtered by magnetron-sputtering technique. The measuring acoustic wave parameters of signal amplitude and phase change were chosen to measure as the sensing parameters. As a result, hydrogen concentration in water solution could be measured by the proposed multi-functional shear-horizontal SH-SAW sensor using Pd-based alloy thin films.
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