Journal of the Japanese Society for Experimental Mechanics
Print ISSN : 1346-4930
ISSN-L : 1346-4930
Volume 14 , Issue Special_Issue
Showing 1-50 articles out of 57 articles from the selected issue
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  • Fumiyoshi KIMURA, Masashi KUROTANI, Kenzo KITAMURA
    2014 Volume 14 Issue Special_Issue Pages s1-s6
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Natural convection around heated horizontal square cylinders placed in water has been investigated experimentally. Main concerns were the flow and heat transfer characteristics of high-Rayleigh number flows. The square cylinders having side length from 10 to 300 mm were utilized as a test cylinder, and they were heated with uniform heat fluxes. The modified Rayleigh numbers based on the side length ranged as; Rad* = 2×105-2×1012. The flow and the surface temperature were visualized with dye and liquid crystal thermometry, respectively. The results showed that the flow ascending along the side surface separates from the upper edges of the cylinder when the modified Rayleigh numbers exceed Rad* = 2×106. The local heat transfer coefficients along the periphery of the cylinder were also measured. The results showed that the coefficients from the upper surface are increased significantly when the above separation takes place.
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  • Toru SAWAI, Noriyasu HIROKAWA, Takeshi KAJIMOTO, Yoshimitsu ICHINO
    2014 Volume 14 Issue Special_Issue Pages s7-s12
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In the present study, a new upgrading solid biofuel, “torrefied wood briquette” that is utilized as co-firing fuels in coal-fueled power plants is proposed. The “torrefied wood briquette” is produced by the torrefaction and compression molding processes to enhance the apparent density and heating value of solid biofuel. To clarify the optimum molding conditions for torrefied woody biomass to mold high density briquettes, experimental studies are conducted on thermo-fluid phenomena and compression molding of torrefied woody biomass. The following results are obtained. (1) The softening temperature increases with decreasing mass yield, water content and pressure. Comparing the two biomass species, the softening temperatures for Japanese cedar are higher than those for pruned sprig of persimmon. (2) The apparent density of briquette has a maximum when the compression molding is conducted at the softening temperature for given mass yield and water content. The torrefaction process gives the trade-off relationship between the heating value and apparent density of torrefied wood briquette.
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  • Takuya SAWADA, Osamu TERASHIMA, Yasuhiko SAKAI, Kouji NAGATA, Mitsuhir ...
    2014 Volume 14 Issue Special_Issue Pages s13-s18
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this study, we developed a hot-film sensor to measure the wall shear stress fluctuation in turbulent flows. The heated element of the sensor, which acts as a sensing part is 10 μm wide and is folded back twice for increasing its electrical resistance to produce heat. In addition, the substrate of the sensor is made up of silicon wafer of 1 μm thickness for increasing the sensor's temporal resolution, in consideration of the substrate's heating capacity. Further, the static/dynamic response test and the measurement of the wall shear stress fluctuation in the boundary layer of the wall jet are performed. The results show that the newly developed hot-film sensor responds to the wall shear stress properly and that its roll-off frequency is 1 kHz. In addition, it is found that the power spectrum of the wall shear stress fluctuation has several peaks. However, no distinct peaks are found in that of the streamwise velocity fluctuation near the wall. This implies that the wall shear stress fluctuation is influenced more by the specified flow structure, such as the coherent vortex structure which arises with a constant frequency in a turbulent boundary layer.
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  • Nurrina ROSLI, Kenji AMAGAI
    2014 Volume 14 Issue Special_Issue Pages s19-s24
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    We propose a simultaneous measurement of liquid surface and wave velocities for falling liquid films on inclined wall. The liquid surface velocity was measured using a non-intrusive technique called as laser tagging method by photochromic dye. The movement of the dye trace tagged by UV laser (λ= 355nm) was recorded by a high speed video camera and analyzed together with the movement of wave passing over the dye trace. As a result, velocity difference between wave and liquid film before the wave passing over was found to increase with increasing wall inclination angle.
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  • Hefeng LIANG, Masatoshi YOSHIDA, Kenji AMAGAI
    2014 Volume 14 Issue Special_Issue Pages s25-s29
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Characteristics of micro hydroelectric generator have been investigated by many researchers for the utilization of renewable energy. However, some problems appeared about the clogging by fallen leaves at the intake part of micro hydroelectric generator. The purpose of this study is to separate the fallen leaves from water using the dust proof screens. The separation experiments are performed in various screen angles and flow rates. The separation ratio of fallen leaves from the water is measured.
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  • Toshiki TAKEICHI, Yasuhiko SAKAI, Osamu TERASHIMA, Kouji NAGATA, Yasum ...
    2014 Volume 14 Issue Special_Issue Pages s30-s35
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this study, new techniques for measuring the concentration of diffusing matter in a liquid axisymmetric turbulent jet is developed based on the laser-induced fluorescence (LIF) method using optical fibers with GRIN lens. Firstly, the concentration measurement of the diffusing matter in a liquid jet by means of two optical fibers is performed. A laser light whose beam spot diameter is 60 μm is emitted on the diffusing matter by means of an optical fiber with condenser lens and the fluorescence is measured by the other optical fiber. Secondly, the concentration measurement in the same liquid jet by means of the same optical fiber which emits the laser beam and collects the fluorescence is performed. Preliminary calibration tests show that the output voltage of the photomultiplier linearly increases with the concentration of the diffusing matter as theoretically predicted in both two measurement techniques. In addition, the mean concentration and fluctuating concentration field in a liquid jet can be measured in both two measurement techniques, whereas the measurement accuracy is better in the measurement with using only one optical fiber from the results of the power spectra of the concentration fluctuation.
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  • Kenji KATOH, Tatsuro WAKIMOTO
    2014 Volume 14 Issue Special_Issue Pages s36-s41
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    It is well known as the wringing phenomenon of gage blocks that a strong adhesive force appears between two smooth surfaces when a thin liquid film is applied on the interface. A theoretical and experimental study is conducted to discuss the wringing mechanism. The liquid film may be separated into a large number of small puddles when two surfaces are rubbed together. One can expect a large adhesive force due to the resultant of surface tension acting on the circumference of each puddle. Numerical results for oil distribution between two surfaces show that the total perimeter length of liquid film reaches 10500 m on the surface of 3cm2, which leads to 1.0×106 (N/m2) for the adhesive force. The adhesive forces measured experimentally roughly agree with the theoretical value. A simple model is proposed to explain the adhesive force dependence on the velocity of pulling apart two surfaces.
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  • Hirokazu ENDO, Fumiya MEGURO, Masanori OTA, Kazuo MAENO
    2014 Volume 14 Issue Special_Issue Pages s42-s47
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    When a high-speed train enters a long tunnel, an air compression wave is generated. This wave propagates in the tunnel at the speed of sound and a pulsed pressure wave is emitted from the tunnel exit. The emitted wave is closely related to the rate of change of pressure as the compression wave arrives at the tunnel exit. Recently, because the running speed of trains has increased, even conventional limited express trains encounter the problem of tunnel pressure wave propagation. In this study we obtained data on the rate of change of pressure and compared the influence of various nose geometries and train speed.
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  • Shintarou YOSHIKAWA, Kazunori KUWANA
    2014 Volume 14 Issue Special_Issue Pages s48-s51
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    When a product of napped fabric catches a fire, the flame may propagate over the surface of the fabric at a high speed. This phenomenon is called surface flash, which is a potential hazard to cause a fire disaster. To prevent surface flash, it is important to understand its spread mechanism.Previously, the effects of nap density and nap thickness were mainly studied. According to these previous studies, surface flash occurs when the following conditions are satisfied: the nap thickness is more than a certain critical value and the nap density is less than a certain critical value. Furthermore, it was found that when surface flush occurs, fire spreading rate is highly dependent on the nap density but little dependent on nap thickness. It was concluded that surface flash mechanism is close to premixed flame rather than diffusion flame. In this paper, the surface flash mechanism is revisited, especially the effects of nap density and nap thickness, by conducting new experiments using a similar experimental setup to the previous studies. Napped cotton sheets of a wide variety of nap densities and nap thicknesses are prepared, a sample is held in the normal direction and ignited from the top, and the spread behavior is recorded using a video camera. A new combustion model of surface flash is proposed based on the experimental results.
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  • Tatsuya NUMAKURA, Kazuki KASHIWAGURA, Toshinori MAKUTA
    2014 Volume 14 Issue Special_Issue Pages s52-s56
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The microbubble generator with a hollow ultrasonic horn is a recent development that can easily generate large quantities of microbubbles with a diameter of less than 100 μm. However, it still presents some drawbacks such as not being able to produce a sufficiently large gas flow rate for industrial applications, whereas the ultrasonic oscillation consumes large amounts of power. In this study, we developed a microbubble generator with an interchangeable orifice, and we evaluated the effect of the orifice shape on optimizing the microbubble generation through the time evolution of dissolved oxygen in oxygen-bubbled water, as well as the distribution of the bubble diameters. We also evaluated whether the generator has the sonochemical qualities required for practical applications by investigating the degree of degradation of indigo carmine. Our results revealed that a multi-orifice horn with orifices that were sufficiently apart to prevent the coalescence of the generated bubbles was well suited for microbubble generation and sonochemical reactions.
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  • Yoshihiro MIWA, Tomomi ARATANI, Tatsuro INAGE, Masanori OTA, Kazuo MAE ...
    2014 Volume 14 Issue Special_Issue Pages s57-s60
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The study of shock wave is of significance in understanding supersonic flow. In this paper the three-dimensional (3D) quantitative measurement unsteady and discharging of shock waves is described. Three-dimensional shock-vortex flow field has been investigated by Laser Interferometric Computed Tomography (LICT) measurement with a diaphragmless shock tube in our laboratory. The complex flow field induced by discharging unsteady shock waves from three cylindrical holes can be successfully measured by pulsed LICT with Algebraic Reconstruction Technique (ART), and results are discussed.
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  • Kazunori HOSOTANI, Koichi NAKATANI, Shota OKAZAKI, Keisuke KAMEI
    2014 Volume 14 Issue Special_Issue Pages s61-s66
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this study, a see-through Stirling engine was designed and constructed to encourage students to interest in engineering education. First, we used laminated acrylic plates and glass syringes to develop the simple see-through Stirling engine. Then, a simple temperature visualization technique was explored to stimulate students to interest and to support design changes that will improve engine performance. Thermochromic liquid crystal films were used to visualize temperature distributions around the cylinder, and drastic thermal changes around the cylinder were shown on the condition that operated an engine as a refrigerator. The result of a questionnaire to junior high school students, who attended the open campus exhibition, shows effectiveness to encourage their interest in engineering subjects.
    In addition, this paper discusses a simple linear 3D flow interpolation method based on 2D-PIV (Particle Image Velocimetry) measurements that assist in understanding the driving mechanism.
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  • Taro HIRASAWA, Naoki SATO, Yuji NAKAMURA
    2014 Volume 14 Issue Special_Issue Pages s67-s70
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Methane flames have been successfully established on the 3 x 3 array of micro burners with a burner diameter of 0.07 mm, even though this burner diameter is smaller than the smallest burner diameter to establish a methane flame.This means that the burner pitch of 2.5 mm is close enough to cause flame-flame interaction to get over the limit of burner diameter and establish clustered microflames. It is found that the NOx emission from clustered microflames is quite low, as low as 6 to 10 ppm at 0% O2, while the CO emission is high level. The NOx and CO emissions from the clustered microflames show different correlation line from other types of burner flames including diffusion microflame.
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  • Toshihiro HANIU, Hiroaki HASEGAWA, Kenichi NAKAGAWA
    2014 Volume 14 Issue Special_Issue Pages s71-s75
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Flying and aquatic animals release a vortex by pitching a wing or a fin. The behavior of this vortex affects unsteady fluid forces, and the propulsive force of these animals relates to unsteady forces accompanied with the movement of vortices. It is well known that vortex motion plays an important role in the generation of unsteady fluid force and enhancement of the force. In general, the force associated with unsteady flow is greater than that of steady flow. Accordingly, conventional quasi-steady theory cannot give the correct assessment of the generating mechanism of the propulsive force. In the present study, generation of the propulsive force in swimming is investigated. The vortex structure and its behavior owing to flow around a discoid airfoil simulating a swimmer's hand are investigated during pitch-oscillating motion. In particular, wind tunnel tests were conducted to investigate the relationship between three-dimensional vortex structure and unsteady fluid forces acting on a discoid airfoil. The vortical flow fields were measured using a scanning particle image velocimetry technique. Under stationary conditions, the vortex ring is successively shed downstream, and the vortex ring inclines as the angle of attack α of the airfoil changes. On the contrary, vortex growth is observed during pitch-oscillating motion, and a large scale vortex is released into the wake close to the airfoil.
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  • Shohei YOSHIKAWA, Hideaki MONJI
    2014 Volume 14 Issue Special_Issue Pages s76-s81
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The paper deals with a distribution problem of solid balls in water at a manifold. In the experiment, a small scale experimental equipment of the manifold was made. The distribution of polystyrene solid particles at horizontal manifolds was measured on the distributed particle number at each tube after the manifold. In order to distribute particles equally, a swirl flow was used at the manifold. The experimental results show that the swirl flow was very effective to change the distribution profile of the solid particles.
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  • Shumpei NOZAKI, Shuhei ICHIKAWA, Hideaki MONJI
    2014 Volume 14 Issue Special_Issue Pages s82-s87
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The objective of the study is to obtain characteristic of the drag force on a sphere behind a cuboid obstacle. The drag force acting on a sphere behind a cuboid was measured experimentally under the various conditions of the obstacle's size and the distance between the obstacle and the sphere. The reduction of the drag force becomes large when the area of cross section of the cuboid is large.
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  • Kentaro NAKAMURA, Khine Tun NAUNG, Hideaki MONJI
    2014 Volume 14 Issue Special_Issue Pages s88-s93
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The study deals with a method to reduce the energy loss due to the velocity slip by using micro bubbles in a supersonic two-phase flow nozzle converting enthalpy of a fluid to its kinetic energy. In the experiment, two micro bubble generation methods were attempted. One is the micro bubble generator using a vortex breakdown, and the other is the pressurized dissolution method with a carbon dioxide gas. The two-phase flow with the micro bubbles became the supersonic flow and was very stable compared with the flow with millimeter-size bubbles.
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  • Sanghyeon SONG, Kazuhiko SOEMOTO, Tatsuro WAKIMOTO, Kenji KATOH
    2014 Volume 14 Issue Special_Issue Pages s94-s100
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    A cleaning device equipped with a special nozzle containing triangular cavities is developed to add high-frequency turbulence to the impinging jet flow. In order to clarify the removal mechanism of fine particles adhered to a wall by van der Waals force, a numerical simulation is performed to estimate various removal forces acting on the particle. Here we examine the effect of the force due to a pressure gradient fluctuation of the impinging jet on removal performance. The numerical results show that viscous drag has the greatest influence, while the pressure gradient force is enhanced by the cavities and has a remarkable effect on the removal of particles larger than 1.5 μm. The numerical results qualitatively correspond to the tendency of measured removal rates for 1.6 μm particles.
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  • Yoshiki NOGUCHI, Keizo NAKAMURA, Yosuke HAGIWARA, Seiya HITOMI, Kazuno ...
    2014 Volume 14 Issue Special_Issue Pages s101-s104
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The aim of this study is to estimate the flame fractal dimensions of methane/air mixtures by experimentally measuring the apparent flame-propagation velocities. In this study, we used an apparatus consisting of two concentric cylinders. It was found that the larger the cylinder size, i.e. the flame scale, is, (i) the more the number of wrinkles of flame is, (ii) the faster the apparent flame-propagation velocity is, and (iii) the values of flame fractal dimension are varied from 1.3 to 2.0. It was also found that the fractal dimension increases with a decrease in equivalence ratio, which is likely because of the effect of preferential diffusion and/or the change in the Lewis number.
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  • Yoshinori NAGASU, Kakumasa EGUCHI, Kazunori ITOH, Makoto OTANI, Noboru ...
    2014 Volume 14 Issue Special_Issue Pages s105-s109
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    This paper presents a method for inspecting micro-holes with diameters of less than 100 μm by using audible sound. Fluid flow through micro-holes affects the performance of a product such as CO gas-detection sensor components, microphone filters, and fuel-injection plates. Therefore, if the flow rate of fluid passing through micro-holes could be accurately assessed by means of an inspection system, it would be possible to guarantee the performance of the product.
    The prototype inspection system used in this study consists of an AC voltmeter, a function generator and a cylindrical metal casing containing a small built-in loudspeaker and a microphone. When a loudspeaker in a sealed casing is driven by a low-frequency sine wave, an excited sound vibrates the air inside the metal casing. The developed system measures the change in pressure at the microphone as the sound wave passes through a micro-hole. It is therefore the same as measuring the flow rate of a fluid passing through a micro-hole. This system is able to detect a 5-μm diameter difference in a micro-hole.
    As the flow rate through a micro-hole can be easily measured, this inspection method is considered to be applicable to micro-hole components intended for use in flow control. Measurement time takes about 1 s after a standard has been set, which is faster than existing measurement methods.
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  • Takenobu SAKAI, Yasunori IIHARA, Satoru YONEYAMA
    2014 Volume 14 Issue Special_Issue Pages s110-s115
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this study, a single-fiber composite was used to evaluate the stress transfer between a single fiber and a matrix. A single steel fiber was inserted into an epoxy resin, and a tensile load was applied to the fiber end. The applied load was 0 N and 177 N. Photoelastic images were then taken by a digital CCD camera. For photoelastic analysis, phasestepping and phase-unwrapping techniques were used to measure the stress difference distribution more accurately. Data calculated using these techniques included 3D information. Therefore, we converted the stress difference data, including the 3D information, to 2D photoelasticity using geometrical information. The maximum shear stress occurred on the side surface of the steel fiber near the fiber end, and the maximum normal stress difference was measured near the surface of the fiber end. The stress distribution on the interface between the fiber and the matrix indicated that the stress was concentrated in the middle of the fiber end and the side surface near the fiber end.
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  • Kensuke KAGEYAMA, Kansuke TAJIMA
    2014 Volume 14 Issue Special_Issue Pages s116-s121
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The loading induced cavitation near the AE sensor attached on miniature tomato was tried to improve the detectability of AE by the compression loading and unloading of the stem via the AE sensor. The AE occurrence rate was rapidly increased after the loading and unloading test. The waveforms of the detected AE showed the various frequency patterns like those generated by the spontaneous cavitation events. These results suggested that the AEs were induced by the loading and unloading test. It is expected that such a technique contribute to improve accuracy of estimation of the embolism risk of tomato plants.
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  • Hiroto YAMANE, Shuichi ARIKAWA, Satoru YONEYAMA, Yasuaki WATANABE, Tat ...
    2014 Volume 14 Issue Special_Issue Pages s122-s127
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    A method for evaluating J-integral for a bi-material interface crack from displacement fields obtained through the measurement using digital image correlation is proposed in this paper. The effectiveness of the proposed method is demonstrated by applying to the displacement fields obtained from elasto-plastic finite element analysis, and the measured displacement fields of specimens with various crack lengths and interfacial strengths. Results show that the proposed method is useful for evaluating the J-integral for an interface crack.
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  • Ichiro SHIMIZU, Noriaki KIMURA, Naoya TADA, Yoshito TAKEMOTO
    2014 Volume 14 Issue Special_Issue Pages s128-s133
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this work, deformation characteristics under indentation testing of metastable β-type titanium-molybdenum alloys were investigated. Ti-14mass%Mo and Ti-20mass%Mo were used to reveal influences of molybdenum content upon indentation behavior. It was found that the traces, which appeared in the surrounding area of indentation, of Ti-14Mo and Ti-20Mo were mainly caused by mechanical twining and crystal slip, respectively. The results also revealed that the dominant deformation mechanism of Ti-Mo alloys influences not only on the piling up around the indentation but also on the evaluated hardness, due to restriction of deformation area by mechanical twinning.
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  • Masahiro SUETSUGU, Noriki INUI, Kouichi SEKINO
    2014 Volume 14 Issue Special_Issue Pages s134-s140
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this paper, the principle of the optical method of caustics is applied to an ultrasonic technique. First, deflection of a longitudinal ultrasonic wave by the effect of geometry is considered using a specimen with spherical dimple. The sequence of a propagating ultrasonic wave is observed directly by using the schlieren technique. Next, the deflection of an ultrasonic wave propagated through a pure bending loaded metallic specimen is evaluated and the relation between the deflection and the coefficient of acousto-elasticity CL is considered. The experimental result shows that the ultrasonic wave is deviated by the effects of geometry and the stress gradient, and the possibility of ultrasonic caustics is confirmed. Moreover, the direction of ultrasonic wave deviation coincides with the sign of CL.
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  • Yuichi ONO, Satoshi SHIRAHASE
    2014 Volume 14 Issue Special_Issue Pages s141-s146
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Young's modulus and Poisson's ratio of electrodeposited metal thin films were calculated by applying the digital image correlation technique. The microstructure of copper thin films was also analyzed by using the electron backscatter diffraction method. First, a program that can calculate sub-pixel displacement was created and a precision stage was used to check its accuracy. Next, tension tests were performed on two metal plates and the program was used to calculate the elastic moduli of the plate materials. The validity of the results was confirmed by comparing the results with those obtained with an electrical strain gage. Finally, the elastic moduli of electrodeposited copper and nickel films were calculated in the same manner. It was clarified that the Young's modulus of the metal thin films was quite small compared with that of the bulk materials. This result is likely due to the difference in microstructure between bulk materials and electrodeposited thin films.
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  • Keita JINNO, Shuichi ARIKAWA, Satoru YONEYAMA, Yasuaki WATANABE, Tatsu ...
    2014 Volume 14 Issue Special_Issue Pages s147-s152
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In this study, an inverse analysis method for determining the material properties from measured displacements for a power-law hardening material is proposed. Displacement distributions on a specimen surface under load are measured using digital image correlation. The virtual fields method combined with the total strain theory is used as a method for inverse analysis. The effectiveness of the proposed method is demonstrated by applying to aluminum specimens under three-point bending. Results show that the material properties after yielding can be identified from the displacement fields by the proposed method.
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  • Hiroyuki YAMADA, Kohei TATEYAMA, Ryo OKUI, Nagahisa OGASAWARA, Kinya O ...
    2014 Volume 14 Issue Special_Issue Pages s153-s157
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The compressive properties of foamed polyethylene (PE) film with a closed cell for electronic devices have been investigated. A commercial closed cell foamed PE film was used. Quasi-static testing was carried out at strain rates of 10−3 to 10−1 s−1. The strain rate of the impact test was approximately 102 s−1 using split Hopkinson pressure bar method. Within the set of experiments, the compressive stress increased with the strain rate. In particular, the flow stress increased substantially with the increasing strain rate in the impact deformation.
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  • Shohei KASUGA, Noboru NAKAYAMA, Sung-Moo SONG, Hiroyuku TAKEISHI
    2014 Volume 14 Issue Special_Issue Pages s158-s164
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    To prevent objects from dropping due to ineffective grasping, robotic hands need to be covered with flexible sensors to determine the magnitude, position, and direction of the applied load. In the present study, a novel sensor was developed, that consists of a hemispherical elastic body and a load measurement layer; the latter is composed of a pressure-sensitive electrically conductive material sandwiched between an upper and a lower electrode. Changing the load on the pressure-sensitive material causes its internal resistance to vary. This gives rise to a change in the voltage measured between the upper and lower electrodes, and allows the load on the sensor to be determined. This study focused on the application of a normal load to different positions on the sensor. The dependence of the voltage change on the magnitude and position of the load was investigated.
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  • Akihiro TAKAHASHI, Naoyuki YAMAMOTO, Toshinobu TOYOHIRO
    2014 Volume 14 Issue Special_Issue Pages s165-s170
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The shielded metal arc welding is mostly popular for fused injection method of metal to metal. The spatter particle appears during the metal arc welding, and then adheres so strongly on the surface of welded plate. Therefore, the commercial anti-adhesive agent is coated on surface of the plate before welding. However, the agent from organic synthesis has several problems, such as environmental influence, stink and expensive. The purpose of this study is to develop the spatter anti-adhesive agent containing a kind of volcanic ash called “Shirasuballoon” which brings the environmental merit, no stink and low cost. In present study, the effect of unique anti-adhesive agent for metal arc welding was reported and discussed based on observation of boundary between spatter particle and metal plate, and mechanical inspections using tensile and impact testing machine.
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  • Shuichi ARIKAWA, Yoichi SENSO, Satoru YONEYAMA
    2014 Volume 14 Issue Special_Issue Pages s171-s176
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    An approach to a wide range strain measurement by combining digital image correlation and bi-sensitive speckle interferometry is proposed. A center notched pure aluminum specimen subjected to a tensile load is used to observe an elastoplastic deformation field. Both the minute strain and the intermediate strain are measured by bi-sensitive speckle interferometry. The large strain is measured by digital image correlation. A data region of the intermediate strain is placed in data regions between the minute strain and the large strain. By combining these data groups using local least squares, a continuous strain distribution of the elastoplastic deformation can be obtained.
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  • Yasushi NIITSU, Takaaki IIZUKA, Kenta YASUOKA
    2014 Volume 14 Issue Special_Issue Pages s177-s181
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Two dimensional displacement of the lighting marker on a plane can be measured with one camera image. However, the measuring process needs the complex calibration of the coordinate system and of the camera states. The developed 2D displacement measuring method can detect the displacements of several four-point LED (Light Emitting Diode) markers, without the complex calibrations. With our method, the camera parameters, which characterize the camera status, can automatically be determined with four positions of the lighting LED on the local coordinate system, for each four-point LED marker. The high-resolution and high-speed camera was used for the development of software and for the displacement measurement. The resolution power of the CCD was 1024x768 pixels for each monochromatic 8 bits resolution, and the sampling interval was 100 times per second. It was confirmed that our method could measure the displacement with enough resolution power, for the purpose of the displacement measurement by the large scale extensometers.
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  • Masahiro NISHIDA, Koji TERANISHI, Shinya OTANI
    2014 Volume 14 Issue Special_Issue Pages s182-s187
    Published: July 01, 2014
    Released: September 03, 2014
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    Dynamic in-plane compressive properties of aluminum alloy honeycombs were experimentally examined. Several cell patterns filled with epoxy resin were examined in order to study how to increase the plateau stress and strain energy density (absorbed energy) of honeycombs. The main reason for the increase of plateau stress and strain energy density was discussed using images captured by a high speed video camera. Deformation modes of honeycomb cells were important for increasing the plateau stress and strain energy density. The effects of intervals and compression direction were examined.
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  • Toshiro KOBAYASHI, Takashi YOKOYAMA, Yuichi UTSUMI, Hideyuki KANEMATSU ...
    2014 Volume 14 Issue Special_Issue Pages s189-s193
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Tensile strain testing was conducted on standard thin films: Tris(8-hydroxyquinolinato)aluminum (Alq3), Bis [N-(1-naphthyl)-N-pheny] benzidine) (α-NPD), and mixed layers of 1/1 Alq3/α-NPD. Alq3 films were found to possess the highest ductility and the ductility of α-NPD thin films was found to improve by mixing with Alq3. In order to improve the ductility of the OLED with a conventional structure of glass/indium-zinc-oxide (IZO)/molybdenum oxide (MoO)/α-NPD/ Alq3/MgAg, the α-NPD layer was replaced by a mixed layer of Alq3 and α-NPD.
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  • Toshiro KOBAYASHI, Hatsuki IKEDA, Yuichi UTSUMI, Hideyuki KANEMATSU, T ...
    2014 Volume 14 Issue Special_Issue Pages s194-s199
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Reduced elastic moduli of organic luminescent materials deposited onto a glass substrate have been measured by nano-indentation techniques. As a result, it could be observed that the reduced modulus of Alq3, α-NPD, and the mixed thin films of Alq3 and NPD are around 12.5–14.0 GPa. Furthermore, the reduced modulus of IZO was around 116 GPa, comparable to that of ITO. In addition, the relationship between stress and strain has been discussed by assuming that the relationship follows a power law. These fundamental data obtained will be applied to the design of flexible organic light emitting diodes (OLEDs) and production equipment using roll-to-roll process.
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  • Nobuhiro MARUOKA, Duk-Yong SONG, Govind S. GUPTA, Hiroyuki SHIBATA, Sh ...
    2014 Volume 14 Issue Special_Issue Pages s200-s204
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In a steelmaking process, metal droplets are emulsified into slag and this phenomenon is called “metal emulsion” Metal emulsions have great potential for improving the reaction efficiency in the steelmaking process. In our previous studies, emulsion formation was experimentally evaluated using a low-melting-point metal and a chloride salt, and the influence of the gas flow rate on emulsion formation was clarified. In this article, the results of previous studies are first summarized and then compared with the results obtained for other systems; finally, empirical equations are proposed.
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  • Hirokazu KONISHI, Takashi BITOH, Hideki ONO, Tetsuo OISHI, Kazuya KOYA ...
    2014 Volume 14 Issue Special_Issue Pages s205-s209
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The leaching solution was prepared from either copper chloride (NH3 solution and NH4Cl) or copper sulfate (NH3 solution and (NH4)2SO4). Copper plates were immersed in these solutions and stirred at 298~353 K. The leaching speed of copper was calculated from the obtained weight loss data. Moreover, influence concentrations of NH3 and NH4Cl were investigated for the dissolution of copper.
    The dissolution of copper was investigated in solutions containing differing concentrations of NH3 and NH4Cl. Insolutions of NH3 (1~6 kmol m-3) and 1 kmol m-3 NH4Cl (0~3 kmol m-3) containing 0.5 kmol m-3 Cu(II) at 313 K, leaching speed increased with increasing NH3 concentration up to 2 kmol m-3 and NH4Cl concentration up to 0.5 kmol m-3. Leaching speed of copper at 600 rpm was calculated to be 3.98 kg m-2 h-1 at 353 K in a solution of 4 kmol m-3 NH3 and 1 kmol m-3 NH4Cl containing 0.5 kmol m-3 Cu(II). The leaching speed of 3.98 kg m-2 h-1 was faster than the 1.65 kg m-2 h-1 obtained at 600 rpm in a solution of 7 kmol m-3 NH3 and 1 kmol m-3 (NH4)2SO4 containing 0.5 kmol m-3 Cu(II) at 353 K. The relationships between V2/3 (stirring speed) and R (leaching speed) were approximately linear in both baths. On the other hand, the elevated bath temperature increased the leaching speed in a solution of 7 kmol m-3 NH3 and 1 kmol m-3 (NH4)2SO4 containing 0.5 kmol m-3 Cu(II). The leaching speed of copper in an ammonia solution containing ammonium chloride was higher than that in an ammonia solution containing ammonium sulfate.
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  • Tadao FUKUTA, Kiyotaka OBUNAI, Koichi OZAKI, Masato TSUTSUI, Takuto HA ...
    2014 Volume 14 Issue Special_Issue Pages s210-s215
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In tensile testing, non-standardized specimens are sometimes used to investigate the tensile characteristics. In this study, an effective method for investigating the tensile characteristics of such non-standardized specimens has been proposed. Two types of specimens made from ductile materials—standardized and non-standardized—were prepared and subjected to uniaxial tensile loads. The test results showed that there was a significant difference in the fracture strain when the non-standardized specimen was used. To evaluate the fracture strain, a new method that considered the absorbed strain energy distribution in the gauge section was proposed. Further, the validity of the proposed method was demonstrated by making comparisons with experimental results.
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  • Yoshinao KOBAYASHI, Kotobu NAGAI
    2014 Volume 14 Issue Special_Issue Pages s216-s220
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The present study aims to clarify the relationship between primary dendrite arm spacing (PDAS), S1[μm], and solidification cooling rate, r[K/s], up to high cooling rate region. Low carbon steel was cast in three kinds of apparatuses and PDAS was measured to be found as function of solidification cooling rate as follows:
    S1 = 0.333×r0.331 (0.62~800 K/s)
    Power factor of r has been discussed in view point of the balance of thermal gradient, G(K/mm), and growth rate of dendrite tip, v(mm/s).
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  • Masashi NAKAMOTO, Toshihiro TANAKA, Takaiku YAMAMOTO
    2014 Volume 14 Issue Special_Issue Pages s221-s225
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    We propose a new method for fabricating iron particles from a porous CaO body and molten iron sulfide by spontaneous wettability conversion. We demonstrate the fabrication of iron particles via our proposed method. In the experiment, iron sulfide and a porous CaO body were reacted under a CO gas flow at 1823 K. Iron particles several micrometers in size were fabricated successfully using our method.
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  • Noboru NAKAYAMA, Hiroto TAMAI, Masaomi HORITA, Hiroyuki MIKI, Hideyuki ...
    2014 Volume 14 Issue Special_Issue Pages s226-s231
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Titanium fiber thin plates were formed by the compression shearing method at room temperature, after which they were sintered. The effects of the number of strain applications (N) and the sintering temperature (T) on the sectional structure and mechanical properties of the formed samples were examined. Normally, biomaterials are required to have a Young’s modulus and tensile strength that are equivalent to those of compact bone. The bonded area of the titanium fibers increased with sintering temperature, thus improving the mechanical properties. Moreover, the density of the titanium fiber thin plate increased with sintering temperature and number of strain applications. Titanium fiber thin plates with N = 0, T = 300–773 K; N = 1, T = 300–773 K; and N = 4, T = 300–573 K are suitable as biological materials because their Young’s modulus and tensile strength are equivalent to those of compact bone. Also, N=0–1, T=823–923 K and N=4, T=773–923 K may be used for aviation structural materials.
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  • Hideki ONO, Minoru MURAKAMI, Jingo ABOSHI, Eiichi TAKEUCHI
    2014 Volume 14 Issue Special_Issue Pages s232-s236
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In order to produce high purity iron (or high clean steel) from low grade ores and/or iron scraps in steel industry, it is necessary to develop a new method to remove the impurities in molten iron, which can improve the refining ability dramatically. In this work, we focus on the reductive removal by using immiscibility of iron and calcium. The oxygen partial pressure is expected to be kept under 10-20 atm by the introduction of calcium alloy phase, which can enhance the reductive removal of impurities in molten iron. In this work, we examine the possibility of the reductive removal of impurities by the use of the calcium alloy phase.
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  • Tatsuya KON, Shin KIKUCHI, Shigeru UEDA, Ryo INOUE
    2014 Volume 14 Issue Special_Issue Pages s237-s241
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    In high-temperature processes, solid, liquid, and gas phases generally coexist together and react with each other. The gas flow in a liquid-containing packed bed is dependent on the liquid and powder distributions, as well as the packed bed structure. The liquid and powder flow in the vacancies of the packed bed because of gravity and gas flow, and move or accumulate there. The accumulation might clog the gas flow. In the present study, the mechanism of liquid and powder accumulation and resulting clogging was investigated with the aim of finding ways to mitigate liquid or powder accumulation in a packed bed. A Discrete Element Method (DEM) model[1] was developed for the analysis of the clogging phenomena, and the relationship between the physical properties of powder and the amount of powder accumulated in the packed bed was investigated. A Moving Particle Semi-implicit (MPS) method[2] was employed for analyzing the liquid flow in the packed bed, and the influence of liquid properties and wettability on its motion was determined. Moreover, experiments were carried out to investigate the interaction between liquid and powder in the packed bed. Further, the influence of wettability and physical properties of the packed material and powder on their accumulation was studied. The wettability of the packed material by the liquid in the bed was found to have a significant influence on powder accumulation.
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Technical Note
  • Takahiro MIKI, Kanna IWADATE
    2014 Volume 14 Issue Special_Issue Pages s242-s244
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Addition of Zn into tool steel is known to improve toughness and it may be used as a countermeasure to utilize steel including brittleness causing impurities such as P etc. However, it is not easy to add Zn into steel due to high Zn vapor pressure at high temperature. Therefore, effective method to add Zn into steel was investigated by reducing ZnO and its compounds ZnAl2O4, Zn2SiO4 and ZnFe2O4 by Fe and Sn was conducted at 1273-1873K. It was confirmed that suitable Zn pressure by ZnO reduction is required for effective Zn addition into steel.
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research-article
  • Jonas A. PRAMUDITA, Yusuke SHIMIZU, Yuji TANABE, Masato ITO, Ryoji WAT ...
    2014 Volume 14 Issue Special_Issue Pages s245-s250
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Porcine skin was subjected to tensile loading in order to determine its anisotropic tensile properties. Skin specimens were obtained from the dorsal and ventral regions of a pig. From each region, two kinds of specimens (parallel and perpendicular to the spine) were tested. Significant difference was detected on the tensile strength between dorsal and ventral regions. Furthermore, anisotropy in tensile properties was also found in both dorsal and ventral regions. Threshold for skin rupture may be different depending on the location and the direction of force.
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  • Li-Mei REN, Yasuyuki MORITA, Mitsugu TODO
    2014 Volume 14 Issue Special_Issue Pages s251-s256
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    Although deformation analysis of alveolar bone with dental implant is crucial, there are no effective experimental approaches in this research field to elucidate the mechanical phenomenon. Our group has suggested an advanced experimental technique to investigate the deformation distribution by means of the combination of a bilayer bone model, which fabricated in accordance with the structure and mechanical properties of actual alveolar bone, and digital image correlation (DIC) method. The validity of the experimental result obtained, however, has not been sufficiently verified yet. Therefore, numerical investigation by finite element (FE) method was performed. As a result, the experimental method combined the bilayer bone model with DIC technique offered important clues to clarify the interfacial state of complex bone deformation distribution pattern around the dental implant, exhibiting its feasibility and usefulness for the research of dental mechanics.
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  • Mohammad ALDIBAJA, Shinichi SUZUKI
    2014 Volume 14 Issue Special_Issue Pages s257-s263
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    This paper proposes an improved Active Shape Model (ASM) to detect the eye shape. The initial estimation of the eye shape and the poor description of its pixel value variation are considered as common problems in ASM. We employ Principal Component Analysis (PCA) to suggest an initial estimation of the eye shape based on understanding the eye structure in an eye image. In addition, the properties of PCA in pixel values-matching and data reduction are used to describe the pixel value variation around the eye shape and to search on the proper locations of the eye shape in the eye image. The experimental results verified the effectiveness of the proposed method compared to the standard ASM.
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  • Mohammad ALDIBAJA, Shinici SUZUKI
    2014 Volume 14 Issue Special_Issue Pages s264-s271
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    This paper presents a robust method for eye shape detection. Existence of eye components such as pupil, iris, eyelid and sclera makes the color variation between the eye and skin very sharp. This variation is measured by applying Principal Component Analysis (PCA) on RGB color channels of an eye image. In addition, eyes have an elliptical structure which can easily be detected in Logpolar domain. Log-polar transform (LPT) decomposes the eye into two parabolas along θaxis. Thus, the eye shape can be detected by searching on corresponding coordinates along log r axis. Based on these properties of eye representation by PCA and LPT, the eye shape is extracted regardless the change of scale, rotation and lighting conditions. The results show high accuracy with reducing time consumption compared to the other existing methods.
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  • Yusuke KANAI, Eisaku UMEZAKI, Shigeyuki MATSUI, Daigo KOMAZAWA, Naoto ...
    2014 Volume 14 Issue Special_Issue Pages s272-s278
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    The movement of mandibular teeth subjected to distal loads from an anchor screw, an orthodontic wire and brackets was investigated using a three-dimensional digital image correlation technique. The experimental model used consisted of the mandible, teeth, periodontal membranes, an orthodontic wire, brackets and an anchor screw. An orthodontic wire with a circular cross section was used. A force of 5.88 N was applied to the brackets bonded on the first and second premolars and the first molar. The direction of the force was set to 0º, 10º or 20º downward from the horizontal. Results indicated that the movement depended on the position and direction of the load. To distally move mandibular teeth connected by an orthodontic wire and brackets without inducing a large rotation or a large extrusion, a distal force directed about 10º downward from the horizontal at the positions of the second premolars is desirable.
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  • Seiichi SUDO, Kohei KITADERA, Atsushi SHIRAI, Toshiyuki HAYASE
    2014 Volume 14 Issue Special_Issue Pages s279-s284
    Published: July 01, 2014
    Released: September 03, 2014
    JOURNALS FREE ACCESS
    This paper describes the details of the movement of wings and body in take-off flight of a butterfly Colias erate Esper. The mechanism of lift generation in take-off flight of the butterfly is considered from the experimental view point. The butterfly generates a rising force even in the upstroke of wing flapping. The butterfly generates not only the vortex-wing interaction but also the lift force based on the usual blade-element theory.
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