実験力学
Print ISSN : 1346-4930
最新号
選択された号の論文の9件中1~9を表示しています
解 説
  • 大木 順司
    2018 年 18 巻 3 号 p. 157-162
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       The mechanical properties of spinal cord and the tissues around it are significantly important to estimate the stress/strain state under the spinal canal stenosis and under the decompression process after the operation using FEM. In this paper, some methods for preperation of specimens of the white/gray matter in the spinal cord, ligamenta flava, dura meter and the nerve root, and the test proceduers for them were explaned. In the compression tests for the white/gray matter in spinal cord of bovine, the specimens were sucessflly formed using the developed puncture needle dropping system, and the collapsing degree of the tissues were evaluated precisely by twice-compressing method. Then the age dependency of the stiffness in human ligamenta flava, and the strain rate dependency of dura mater of bovine were found through the tensile tests by the low-high speed testing system. The two-dimensional strain field in the nerve root of pig were sucessfully measured through DIC method, where the blue sand of hour-grass was adopted for making random pattern on the specimen surface.

論 文
  • 石井 慶子, 麓 耕二
    2018 年 18 巻 3 号 p. 163-168
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       The mechanism of Pulsating Heat Pipe (PHP) is still unclear because of its complex thermal fluid property. There are few researches that measured the temperature distribution inside the PHP. This study executed the visualization of temperature distribution inside a PHP. Temperature sensitive paint was painted on the optical window. The TSP was excited by UV LED light and the luminescence intensity was captured by CMOS camera. The fluid and wall temperature inside the PHP was measured instantaneously. We captured a thermal flow induced by the evaporation and oscillation. The measurement accuracy was 0.2 ° C. We measured the temperature of working fluid adhering to the wall surface that was colder than the ambient temperature. When the flow was oscillating, the temperature at an arbitrary point inside the channel was fluctuated. On the other hand, when the low was circulating, the temperature at the channel became stable apparently. Acquired data was qualitatively in agreement with known PHP properties. Temperature measurement by TSP is considered to be effective for PHP performance evaluation and flow mechanism investigation.

  • 上浦 友洋, 高橋 進
    2018 年 18 巻 3 号 p. 169-175
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       Variations in tensile properties and temperature rise of Dual Phase sheet steel with strain rate were investigated. The uniform elongation did not change much, but the local elongation decreased over a range of strain rates from 0.001/s to 5/s. The material temperature was about 300K during uniform tensile deformation. In quasi-static tensile tests, the n value did not change at a temperature of less than 373K or less, but increased at a temperature of over 473K. Softening of the sheet did not occur at slow strain rates because the temperature rise was very small. Similarly, at a strain rate of 60/s, uniform elongation remained unchanged, but local elongation increased. The temperature during uniform elongation was about 300K, but exceeded 473K at the end of local elongation, resulting in increased local elongation. Strain increased during all of elongation at a strain rate of 1260/s or more. The following conclusions were obtained for the elongation. At strain rates less than 5/s, stress concentration due to temperature difference causes local elongation to decrease as the strain rate becomes faster. At strain rates above 60/s, the local elongation as well as the n value increased due to softening of the sheet steel caused by plastic heat generation.

  • 小野 勇一, 野村 武弘, 森戸 茂一
    2018 年 18 巻 3 号 p. 176-183
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       When an electrodeposited copper or nickel foil is subjected to a repeated load, grain growth occurs in the foil. Since the thermal recrystallization occurs when the ambient temperature rises, the upper limit of the ambient temperature is limited to 80 ℃ and 250 ℃ for the copper foil and the nickel foil, respectively. In this paper, the cyclic stress measurement utilizing grain growth of a nickel alloy foil under high ambient temperature was investigated. First, the nickel alloy foil was heat treated under various conditions. Then the grain size was analyzed using EBSD and XRD in order to check whether grain growth occurred. Moreover, the pulsating tension tests were carried out under 350 to 400 ℃, and the grain size was also analyzed. It was revealed that the nickel alloy foil was recrystallized at a temperature of 350 to 450 ℃. Moreover, the grain growth due to cyclic loading could also be confirmed under 350 to 400 ℃. Therefore, the possibility of stress measurement by nickel alloy foil under high temperature environment was suggested.

論 文
  • 下代 昇平, 谷本 道哉
    2018 年 18 巻 3 号 p. 184-191
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

    Recently, athletes tend to focus on trunk stability during sports movements. Trunk stability is thought to play the role of an upper and lower limbs' foundation and to improve transfer capacity of power from the lower limbs to the upper limbs. Intra-abdominal pressure (IAP) development is considered to be important for trunk stability training exercises such as planks. The purpose of this study was to examine how IAP changed in sports movements and to compare IAP during various types of movements. Ten healthy men with resistance training experience of more than 1 year performed movements. Maximal IAP during the valsalva maneuver (maxIAP) was measured. The subjects performed trunk stability training (TST), trunk muscles resistance training (TRT), upper and lower limbs movement muscles resistance training (LRT) and dynamic sports movement (DSM). IAP value during TST (8~19%maxIAP) was significantly lower than that during DSM and LRT and was almost the same as that during TRT. IAP value during DSM was the highest (37~62%maxIAP) in all movement groups. IAP value correlated at erector spinae muscles electromyography (EMG) during TRT, LRT and DSM (P<0.05). These results suggest that IAP development did not appear during TST. IAP development may be related to trunk extension moment.

  • 髙橋 秀行, 壁矢 和久
    2018 年 18 巻 3 号 p. 192-198
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       To improve surface quality, the jet wiping method is used to control the coating thickness in a continuous galvanizing line. In this study, we adopted structural technology for the wiping nozzle with the aim of suppressing nozzle clogging, which is the main problem with the standard wiping process, and reducing the uneven coating thickness in the direction of strip width. We adopted a laminated piezoelectric device for the actuator, which is a key smart structure technology, and attempted to change the nozzle gap statically / dynamically. Regarding the static change, it was confirmed by the actual nozzle that the actuator specification could be examined by FEM analysis and a gap change of about 0.1 mm would be possible. We also succeeded in vibrating at high frequencies of 20 μm amplitude and 810 Hz by utilizing the resonance in the opening and closing vibration mode of the upper and lower lips. The nozzle was subjected to an on-line test in an actual plant, and suppression of nozzle clogging due to high frequency excitation and great improvement of the distribution of coating thickness in the direction of strip width due to expansion of the gap were confirmed.

  • 吉川 晃, 池田 清彦, 越智 秀, 小堀 修身
    2018 年 18 巻 3 号 p. 199-205
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

    Partially stabilized zirconia is a useful material toughened by a stress-induced transformation, and often applied in the medical field. However in our previous study an appreciable degradation of lifetime by cyclic loading was observed. And such a cyclic effect was supposed to be due to the occurrences of micro-cracks in transformation zone near the crack tip. In this study two methods adding pre-loading stress before adding cyclic loading stress were suggested to restrain the occurrences of micro-cracks. One is the method adding a pre-loading stress close to the transformation-induced stress before indenting a pre-crack to the surface of specimen, and the other is that adding a pre-loading stress more than the cyclic loading stress after the indentation. The test results indicated that the latter method could make the lifetime appreciably increase in cycling fatigue with a low applied stress. It was supposed that the transformation zone formed in front of crack tip by pre-loading stress restrains the occurrence of micro-cracks and the process zone wake extended behind crack tip with crack growth causes the increases of crack resistance due to the closure stress over the crack surface.

  • 澤野 宏, 南 賢太
    2018 年 18 巻 3 号 p. 206-213
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       An optical probe can measure the shapes of specimens in a perfectly non-contact condition, and has a high vertical resolution. Therefore, an optical probe is widely used for the profile measurement. However, optical probe has a problem that the low lateral resolution. Lateral resolution of an optical probe depends on the spot size of the laser at the measurement point, and is generally lower than one order of magnitude than the vertical resolution. By the improvement of the Lateral resolution of an optical prove, the improvement of the measuring accuracy and of the application can be expected. Therefore, this study newly proposed an optical probe with the high lateral resolution by the collecting laser irradiation. In this study, we constructed an optical probe utilizing concentrated laser irradiation from multiple directions and conducted the principle verification experiment. Furthermore, the relationship between the step profile and the optical probe output in the step standard specimen was investigated and the usefulness of the proposed measurement method for improving lateral resolution was evaluated.

  • 南川 久人, 松村 怜, 畑 直樹, 原田 英美子, 栗本 遼, 安田 孝宏, 宮嵜 一樹
    2018 年 18 巻 3 号 p. 214-221
    発行日: 2018/10/11
    公開日: 2018/10/12
    ジャーナル フリー

       Effects of zeta potential of microbubbles on plant growth of Japanese mustard spinach (Brassica rapa var. perviridis) in soilless culture were evaluated. Experiment (i) dealt with two kinds of concentrations of nutrient solution (10 or 100% concentration) and three kinds of pH (4.5, 5.5 and 6.5). Microbubbles were adopted only in the 10% concentration plot. Experiment (ii) dealt with the above two concentrations of nutrient solution with and without microbubbles at pH 4.5. Zeta potential at pH 6.5 was larger than that at pH 4.5. The experiment (i) showed that the growths of the plants in pH 4.5 plot with microbubble were inhibited, whereas the plants in pH 6.5 plot with microbubble grew better than those in other plots. In the experiment (ii), the inhibition at pH 4.5 due to microbubbles appeared regardless of the concentration of solution. Multi-element determination revealed that absorption of K or Ca was enhanced at pH 6.5 and reduced at pH4.5 due to microbubble. These results indicated that microbubble treatment in low-concentration nutrient solution could promote mineral uptake by roots, which results in enhancement of plant growth, as long as zeta potential of microbubbles is adequately large.

feedback
Top