実験力学
Print ISSN : 1346-4930
ISSN-L : 1346-4930
16 巻, 4 号
選択された号の論文の8件中1~8を表示しています
論 文
  • 蔭山 健介, 魯 子暁, 菅原 拓也, 坂井 建宣
    2017 年 16 巻 4 号 p. 295-300
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       Electret condenser sensors (ECS) is suitable for detection of ultrasounds propagating air and soft materials because it has an air gap in the element. In this study, ECS were fabricated to detect artificial acoustic emission (AE) propagating a wood plate and AEs at a trunk of acerola. ECS demonstrated the higher S/N ratio from 40 to 100 kHz for the detection of the artificial AEs than a piezoelectric AE sensor (PS) and a wideband acceleration sensor (AC). The AEs detected by ECS showed several frequency peak from 50 to 200 kHz at the AE measurement at a trunk of acerola while the AE detected by PS also showed wide frequency from 100 to 500 kHz. Furthermore, the ECS had the same degree of sensitivity as PS at AE measurement at the trunk of acerola while AC hardly detected the AEs. The AE behavior of ES, however, did not partially coincide with the significant increase of AE events of PS. Hence, the long-term reliability of ES must be investigated for practical use of AE measurement of woody plants.

  • ~赤血球把持方法の検討~
    中村 匡徳, 池田 拓郎, 氏原 嘉洋
    2017 年 16 巻 4 号 p. 301-306
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       Tensile tests of single red blood cells have been conducted to determine their fracture strain for the development of a hemolysis simulator. The red blood cells were however detached from holding tools before their membrane broke down due to their high elasticity. The present study therefore examines means and conditions to firmly hold single red blood cells in the tensile tests. We tested urethane and epoxy resin as a glue, and examined a needle and a micropipette as a holding tool. Tensile tests were repeated with various combinations of the glue and the holding tool. Examined parameters for the glues were a dry time in the air (Ta), an underwater hardening time (Tw) and a fixation time (Tf). The fracture of single red blood cells was achieved when the urethane was used as a glue and the micropipette was adopted as the holding tool. The red blood cell failed via fracture at a deformation ratio of 5.32. In this achievement, Ta, Tw and Tf were 300 s, 90 s and 1800 s, respectively. The results suggested use of urethane as a glue and micropipette as the holding tool for determining the fracture strain of the red blood cells by tensile tests.

  • 西尾 康宏, 伊藤 安海, 岸田 亮太郎, 鍵山 善之, 根本 哲也
    2017 年 16 巻 4 号 p. 307-314
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       In this research, we investigated dynamic viscoelasticity properties of human skin, Hitohada gel (urethane gel), and porcine fat in order to make dummy skin which could be used for safety evaluation. The Hitohada gel is a material which has a hardness equivalent to human skin. As a result of the initial investigation, it has been revealed that the dynamic viscoelasticity properties of the Hitohada gel are different from that of human skin. Thus, we have focused on the tension of the human skin. In the investigation, the test dummy, which was made of the Hitohada gel and covered with tensioned dressing material, showed a similar dynamic viscoelasticity property to human skin. With these results, we consider that dummy skin is required to imitate not only the dynamic viscoelasticity property but also the tension of epidermis of human skin. In addition, we also have succeeded in developing dummy skin, whose hardness and dynamic viscoelasticity properties are similar to those of males in their 20s.

  • 加藤 禎菜, 福田 早紀, 鈴木 康雄, 太田 進
    2017 年 16 巻 4 号 p. 315-319
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       Visual display terminal (VDT) tasks induce misaligned posture, resulting in increased neck and shoulder pain. This study investigated the effect of a posture feedback band on posture alignment and pain during a VDT task. Eight healthy individuals participated in which a custom-made posture feedback band with a length sensor sheet was applied to provide postural feedback. All subjects were exposed to Condition C (without the band) and Condition F (with feedback) on separate days during a 20-minute VDT task for all subjects. The angle of the forward head position was significantly smaller in Condition F compared with Condition C, which indicated improvement of the forward head position based on the feedback from the length between both scapulae. Eye, shoulder, and lumbar pain, however, were all significantly increased by the VDT task, both with and without postural feedback.

論 文
  • 関野 晃一, 松本 健司, 阿久津 敏乃介
    2017 年 16 巻 4 号 p. 320-325
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       In this paper, the effect of specimen size on compression splitting tests is investigated experimentally by the caustics method. Specifically, we investigated the stress intensity factor and compression load ratio KI/P by varying the specimen width d from 10 to 60 mm, height h from 20 to 100 mm, notch length a from 4 to 36 mm, thickness t from 3 to 10 mm, and platen width w from 3 to 12 mm, respectively. The experimental KI /P values are shown to approximately coincide with values calculated using the compression splitting method for a notch lengths of 15 and 20 mm, a thickness ranging from 6 mm to 10 mm, a width of 15 mm, a height ranging from 20 mm to 100 mm, and a platen width ranging from 6 mm to 12 mm, within the accuracy of experimental conditions of the present study.

  • 内海 秀幸, 菅 洋志, 鈴木 誠, 安田 知弘
    2017 年 16 巻 4 号 p. 326-331
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       Thermal dehydration relating to the various water content conditions (including saturation) of hardened cement pastes was studied using non-isothermal thermogravimetry at three rates of linear increase of temperature from 30℃ to 420℃. The experimental data examined includes evaporation of free water in the pore spaces, dehydration of physically bonded water and decomposition of hydrated water. The influence of heating rates and water content gives to dehydration profiles were clarified. Ozawa method was used to determine activation energy. In the present work, activation energy changed depending on water content. Additionally, dehydration processes under constant temperature conditions were estimated.

  • 高見 誠二, 井口 学
    2017 年 16 巻 4 号 p. 332-341
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

       Many types of gas injection systems are employed in the current refining processes. Cold model experiments have extensively been carried out to find out an optimum gas injection condition by focusing on the mass transfer between the injected gas and molten metal in the bath. The top and bottom gas injection process is treated in this water model study. Emphasis is placed on an optimum combination of the positions of top lance and bottom gas injection nozzles because the positions are closely associated with the process efficiency. The conventional mass transfer method however is not easy to carry out and treatment of used liquids containing undesirable materials is not necessarily inexpensive. A method of finding out the optimum combination was proposed on the basis of an analogy between heat and mass transfer. The heat transfer between injected gas and water in the bath was measured for validating this method.

  • Kentaro URATA, Yoshinao KOBAYASHI
    2017 年 16 巻 4 号 p. 342-347
    発行日: 2017/01/23
    公開日: 2017/01/23
    ジャーナル フリー

    The solubilities of copper and sulfur in solid iron have been investigated at temperatures of 1073, 1173, 1273 and 1573 K. The samples were prepared from electrolytic steel plate, Cu2S powder, FeS powder and iron powder, and then subjected to analyses by an electron micro probe analyser (EPMA). The equilibrium concentrations of copper and sulfur in solid iron are much higher than the apparent solubilities of copper sulfide reported for Fe-3mass%Si steel. The possible reason is that the copper sulfide precipitates form in the concentrated region of copper and sulfur induced by micro segregation during solidification. In addition, the existence of copper sulfide has been verified in samples having the composition of Fe-0.1mass%Cu-0.01mass%S-0.1mass%C, without and with annealing for the homogenization after melting and solidification process. The annealed sample did not cause any copper sulfide precipitation in SEM images, while as-cast sample yielded the one. On the basis of Scheil's equation, super-saturated region has been calculated to be 0.1vol%, which ratio is a little larger than the actual copper sulfide precipitates shown in the SEM images. Thus, micro-segregation will contribute to copper sulfide precipitation in solid iron even when the copper and sulfur concentrations are low.

feedback
Top