Kagoshima National College of Technology

Kagoshima, Japan

Kagoshima National College of Technology

Kagoshima, Japan
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Odahara S.,Kagoshima National College of Technology
Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A | Year: 2012

For the safety and reliability of small size Wind-lens turbine, several experiments of mechanical properties of blade's material, Dicyclopentadiene was conducted. Vickers hardness was Hv =13.8 independent of load times and load magnitudes. Fatigue strength of the specimen contained some scale voids were quite low compared to the plain specimen contained no voids. Fatigue strength of notched specimens was lower than that of plain specimen. Non-propagating fatigue crack was not observed on this material. Fatigue crack growth property was obtained by three point bending fatigue test. The relationship between fatigue crack growth rate and the stress intensity factor range, ΔK, was obtained. Charpy impact absorption energy of Dicyclopentadiene was three times as that of ABS resin. © 2012 The Japan Society of Mechanical Engineers.


Tsutsumi T.,Kagoshima National College of Technology
45th US Rock Mechanics / Geomechanics Symposium | Year: 2011

In this paper, the distribution of principal tensile stress in an orthotropic rock specimen under a diametrical compression test is shown. This distribution was obtained by calculation using Lekhnitskii's theoretical solution and an additional equation formulated by Kawakubo, et al. Concentrated force was adopted as the boundary condition that can be represented by FEM. Calculation was carried out in several directions along the principal elastic axis. Graphical representations show that the tensile principal stress which occurs in the direction of larger elastic modulus is larger than that which occurred in the direction of the smaller elastic module. They also show that the tensile stress which occurs in the direction perpendicular to the loading direction along the loading radius is the same as the principal tensile stress unrelated to its angle of the direction of principal elastic axis in the loading direction. Finally, the results of this study were compared with those obtained by Claesson et al. and some differences between them are shown in graphical representations. © 2011 ARMA, American Rock Mechanics Association.


Tsutsumi T.,Kagoshima National College of Technology
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics | Year: 2012

In this paper, the method of determining the orthotropy ratio and the direction of the principal material axis in an orthotropic brittle material using a diametrical compression test is shown. In this method, the strain values and angles of the principal strain with respect to the loading direction are calculated at the center of the cross section for several orthotropy ratios and several angles of direction of the principal elastic axis in the loading direction by means of theoretical solution. The relation between the ratio of these strain values and the direction of the principal elastic axis, and the relation between the direction of the principal strain and that of principal elastic axis are shown as graphical representations. When the strain values and the directions of the principal strain obtained using Rosette gages are applied to these graphical representations, the orthotropy ratio and the principal material direction of this disk can be determined. © 2012 Taylor & Francis Group, London.


Tsutsumi T.,Kagoshima National College of Technology
46th US Rock Mechanics / Geomechanics Symposium 2012 | Year: 2012

The distributions of the principal tensile stress in orthotropic Brazilian Disk were shown under a pair of concentrated forces and compared with those by Claesson in previous author's work. It was observed that the stress distributions are influenced by the angle of the disk's orientation and the ratio of the elastic moduli. In this paper, the distributions of the principal tensile stress that is generated in the Brazilian disk are shown for several contact areas between the specimen and loading plates under the diametrical compression test. In this study, the load on the specimen is assumed as uniform distributed stress. The distributions of principal tensile stresses are obtained by calculation using Lekhnitskii's theoretical solution and the equation that was added by authors. Calculations to obtain the principal tensile stresses are carried out under severalorientations of disk. Graphical representations show that the tensile stress that is generated near the loading plates decreases as the contact area between the specimen and loading plates increases. On the other hand, the tensile stress generated at the center of disk decreases by only a small amount as the contact area increases. Copyright 2012 ARMA, American Rock Mechanics Association.


Yoneda M.,Tohoku University | Nozawa H.,Kagoshima National College of Technology | Misawa H.,Tohoku University | Kagitani M.,Tohoku University | Okano S.,Tohoku University
Geophysical Research Letters | Year: 2010

Monitoring observations of Jupiter's sodium nebula and [SII] 673.1 nm emission from the Io plasma torus were made for 20 days in 2003. During these observations, the brightness of the sodium nebula showed a small enhancement which seemed to be caused by Io's volcanic outburst. During this enhancement, [SII] 673.1 nm brightness and the ion temperature (scale height) along Jupiter's magnetic fields did not show any significant change, but magnetic flux tube content of S+ ion was calculated from the [SII] 673.1 nm brightness and the scale height, and an increase of the ion flux tube content was clearly identified. Thus, increase of supplied plasma from Io seems to be reflected in both plasma density and ion temperature. We conclude that Io's volcanic enhancement with a duration time of a few days can change Jupiter's inner magnetospheric environment in aspects of both ion density and temperature. Copyright © 2010 by the American Geophysical Union.


Kondoa E.,Kagoshima University | Shimanab K.,Kagoshima National College of Technology
Procedia CIRP | Year: 2012

The purpose of this study is to investigate effectiveness of the thrust force, the motor current of spindle, and the AE signals from workpiece for the monitoring of the prefailure phase and the detection of the tool breakage in drilling holes through a thin stainless steel plate (JIS SUS304). The thrust forces, the motor current, and the AE signals were measured in micro-drilling tests by using the micro-drills of 0.1-0.3 mm in diameter. After some considerations of experimental data, it was revealed that the thrust force is the most suitable for both the monitoring of the prefailure phase and the detection of the tool breakage, the motor current for the monitoring of the prefailure phase of the tool breakage, and the AE signal for the detection of the tool breakage. © 2012 The Authors.


Wang W.-X.,Kyushu University | Matsubara T.,Kyushu University | Hu J.,Kyushu University | Odahara S.,Kagoshima National College of Technology | And 3 more authors.
Renewable Energy | Year: 2015

Wind tunnel experiments were conducted to investigate the influence of the flanged diffuser on the dynamic behavior of the blade of a 3kW wind turbine shrouded with a flanged diffuser. The blade was fabricated by the skin of carbon fiber reinforced plastic and solid foam core. Tests were carried out for three wind velocities (6.9m/s to 11.6m/s) and three different yawing angles (0-degree to 30-degree) to investigate the effects of the interactions of the flanged diffuser and the yawing angle on the blade. The rotational speed of the blade and the dynamic strain near the blade root were measured under the conditions with and without the flanged diffuser. Two telemeter systems of transmitter and receiver were used in the measurement of the dynamic strains of the rotating blade. The mechanical tests of the blade and the skin of the blade were also performed to obtain basic data for the estimation of the strength of the blade. Experimental results reveal that the rotational speed and the dynamic strain of the blade of the wind turbine with a flanged diffuser are much higher than those without a flanged diffuser. © 2015 Elsevier Ltd.


Fuchiwaki M.,Kyushu Institute of Technology | Kuroki T.,Kyushu Institute of Technology | Tanaka K.,Kyushu Institute of Technology | Tababa T.,Kagoshima National College of Technology
Experiments in Fluids | Year: 2013

Micro-air-vehicles (MAVs) and micro-flight robots that mimic the flight mechanisms of insects have attracted significant attention in recent years. A number of MAVs and micro-flight robots that use various devices have been reported. However, these robots were not practical. One of the reasons for this is that the flying mechanism of insects has not yet been clarified sufficiently. In particular, the dynamic behavior of the vortex formed on the insect wing and its growth process have not been clarified. The purpose of the present study is to clarify the dynamic behavior and the detailed structure of the vortices of the flapping butterfly wing. The authors conducted a particle image velocimetry measurement around the flapping butterfly wing of Cynthia cardui and Idea leuconoe and investigated the vortex structure of the wing and its dynamic behavior. A vortex ring is formed over the butterfly wings when the wings flap downward to the bottom dead position. The vortex ring then passes over the butterfly completely and grows until reaching the wake at the bottom dead position. The vortex ring is formed over the wings regardless of the type of butterfly, although the scale of the vortex ring varies with the butterfly type. © Springer-Verlag Berlin Heidelberg 2012.


Tsutsumi T.,Kagoshima National College of Technology
Zairyo/Journal of the Society of Materials Science, Japan | Year: 2011

In this paper, the method of determination for anisotropy ratio of orthotropic brittle material in diametrical compression test is shown. For this method, strains are calculated on the direction of parallel and normal to compression at the center of cross section under several anisotropy ratios with theoretical solution. And the relationship between ratio of these strains and anisotropy ratio is shown by the graphical representation in this paper. Using this graphical representation, anisotropy ratio can be obtained with measuring strains occurred at center of cross section of specimen. © 2011 The Society of Materials Science, Japan.


Tsutsumi T.,Kagoshima National College of Technology
Zairyo/Journal of the Society of Materials Science, Japan | Year: 2011

In this paper, the method of determination the orthotropy ratio and the principal material direction of orthotropic brittle material in diametrical compression test is shown. For this method, strains and angles between principal strain and the direction of load are calculated at the center of cross section under several orthotropy ratios and several angles between direction of load and principal material direction by theoretical solution. The relation between ratio of these strains and principal material direction, and the relation between the direction of principal strain and that of principal material direction are shown by graphical representations in this paper. When strains and directions of principal strain obtained by rosette gages are applied to these graphical representations, the orthotropy ratio and the principal material direction of this specimen are able to be determined. © 2011 The Society of Materials Science, Japan.

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