Advanced Experimental Mechanics
Online ISSN : 2424-175X
Print ISSN : 2189-4752
ISSN-L : 2189-4752
早期公開論文
早期公開論文の9件中1~9を表示しています
  • Nobuhiro YABUKI, Natsuki MURAKAMI, Kodai HASEGAWA, Wenjing XING, Toshi ...
    原稿種別: research-article
    論文ID: 24-0014
    発行日: 2024年
    [早期公開] 公開日: 2024/06/27
    ジャーナル フリー 早期公開

    A hollow ultrasonic horn can generate microbubbles by breaking down the gas-liquid interface with ultrasonic oscillation in various liquids, including not only water but also highly viscous and corrosive liquids. On the other hand, as the flow rate of the supplied gas increases, the ultrasonic waves do not sufficiently disturb the gas-liquid interface, resulting in the generation of many large bubbles. The purpose of this study is to improve the miniaturization performance of the hollow ultrasonic horn to suppress the generation of large bubbles at high flow rates. Therefore, we evaluated the conventional horn whose ultrasonic oscillation is only longitudinal oscillation and a complex oscillation horn with longitudinal and torsional oscillation. The process of bubble generation, dissolved oxygen concentration, and bubble diameter distribution were investigated. As a result, there was no significant change in the diameter of miniaturized microbubbles in each horn, but the complex oscillation succeeded in suppressing the frequency of generation of large bubbles and increasing the amount of microbubbles generated.

  • Carlos Rolando RIOS-SOBERANIS, Takenobu SAKAI, Shuichi WAKAYAMA, Emili ...
    原稿種別: research-article
    論文ID: 24-0017
    発行日: 2024年
    [早期公開] 公開日: 2024/06/27
    ジャーナル フリー 早期公開

    Geotubes are the most used technology for coastal recovery due to erosion and, because of the lower price and easier installation, geotextile tube systems can be good alternatives for hydraulic and coastal structures. Geotubes can suffer damage due to cuts in fibers and other components, formation of holes, abrasion originating a reduction in mechanical resistance. On the other hand, when filled in-situ by hydraulic pumping is assumed that tensile stresses act directionally due to the hydraulic pressure and the tensile force in the geosynthetic tube. Therefore, it is important to understand the mechanical behavior as well as to identify the stages during the damage process. A mechanical vital role is sustained by the textile architecture and configuration since stresses will be transferred along the textiles. This paper exhibits the full mechanical characterization of two geotextiles made of polyethilenethereftalate (PET) and polypropylene (PP) respectively, both with different interweave architecture. Results found that textile geometry is crucial for bearing stresses and depend on the acting direction. Acoustic emission technique was employed to identify the mechanism of failure that supported the mechanical characterization findings.

  • Yohsuke TANAKA, Hiroki MATSUSHI, Dai NAKAI
    原稿種別: research-article
    論文ID: 24-0001
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    The study focuses on the elongation of reconstructed microparticles in holographic particle measurement. We propose a theoretical formula for particle elongation that requires the determination of the coefficient 𝑚. Previously, the coefficient was set as 2 based on particle size distribution comparisons. However, its suitability computational for other diameters was unclear. We directly compare elongation from particle patterns printed on a glass plate with varying diameters to the theoretical formula. We found that 𝑚 is equal to 1, not 2. This finding is crucial for accurate holographic particle measurement.

  • Satoru YONEYAMA, Keisuke IIZUKA
    原稿種別: research-article
    論文ID: 24-0003
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    This paper proposes a method for evaluating J-integral from measured displacements based on the finite strain theory.Logarithmic strain components in the material coordinate system are evaluated from displacements measured using digital image correlation. A finite element model is utilized to obtain the logarithmic strains as well as the displacement gradients from measured displacement distributions. Then, the stresses are computed from the logarithmic strains using the incremental strain theory. Finally, the J-integral values are obtained numerically using the domain integration. The effectiveness of the proposed method is demonstrated by applying it to the displacement fields measured by digital image correlation. The Jintegral values obtained using the proposed method are compared with those obtained based on the small strain theory and with those obtained from the HRR displacement fields. Results show that the J-integral evaluation based on the small strain theory and that from the HRR displacement fields underestimate the J-integral values.

  • Kenji GOMI, Masashi NITANDA
    原稿種別: research-article
    論文ID: 24-0004
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    Currently, there is no technology that facilitates the nondestructive and contact-free estimation of the peel load of the heat seals of food and other packages in the production line. To address this gap, this study proposed a method using laser photoelasticity. Considering the environmental impact of plastics, biodegradable resin polylactic acid was selected as a sample, and the optical retardations of the sealed section of the specimens were measured by changing the seal temperature in the range of 80–105 ºC. The specimens were then peeled off using a tensile tester, and the loads were recorded. The relationships among the optical retardation, peel load and sealing temperature exhibit dependence on the combination of the machine direction (MD) (direction in which the resin film is stretched during manufacturing) and the direction of the sealing line. This was because the polymer chains were oriented in the MD in advance, and the orientation changed along the sealing line owing to temperature and pressure caused by heat sealing. The MD and sealing temperature at the manufacturing site are known; therefore, it was suggested that it should be possible to obtain a rough estimate of the peel strength using the photoelastic method. However, care would have to be taken, because the estimation accuracy might reduce, further depending on the combination of the MD and seal line.

  • Kei UENO, Keisuke IIZUKA, Satoru YONEYAMA
    原稿種別: research-article
    論文ID: 24-0005
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    This study proposes a method for determining an optimal subset size for digital image correlation. The optimal subset size is defined as that minimizes measurement error. Estimation equation of optimal subset size is proposed based on existing theoretical error model. The estimation equation is a function of 2nd-order displacement gradient (state of deformation), standard deviation of image noise (conservation of intensity values before and after deformation), and mean intensity gradient (speckle pattern quality) as parameters. Measurement errors for various subset sizes are computed in numerical simulations using synthetic speckle images with various measurement condition. For each parameter change, the optimal subset size derived from the measurement error and its estimation equation varies similarly. The analysis of computer-generated speckle images imposed FEM-displacement simulating tensile tests are also conducted and the results indicate the validity of the estimation equation.

  • Ichiro SHIMIZU, Shunpei UEDA, Akira WADA, Tomoya KAGOTANI, Yoshito TAK ...
    原稿種別: research-article
    論文ID: 24-0007
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    Coronary stents are thin-walled cellular structures constructed by connecting unit cells in the circumferential and axial directions. The unit cell is subjected to in-plane bending during the expansion process in the diseased artery. As the simple test method to evaluate the in-plane bending and contribute to the design of the stent unit cell shape, the rhombus-shaped specimen having the curved part and the straight part was suggested. The experimental and analytical investigations were performed on the rhombus specimen made of AZ31 magnesium alloy, and the influences of the design parameters on the strain gradient in the curved part and the deformability were investigated. The results proved that the rhombus-shaped specimen was useful to investigate the in-plane bending of the cellular structure. The in-plane strain gradient from tensile to compressive was found to occur in the curved part. Changing the design parameters of the rhombus specimen influences not only the deformability but also the tensile load, namely the force to keep the artery open. It should be emphasized that the addition of the appropriate length of a central straight part was found to be effective in improving the deformability of the cellular structure.

  • Tadao FUKUTA, Manato KANESAKI, Koichi OZAKI
    原稿種別: research-article
    論文ID: 24-0008
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    This study aimed to examine the impact of variations in Mg and Cu content within the Al-Mg-Zn-Cu cast alloy on its strength characteristics, utilizing JIS-AC7A as the base material. Two alloys were considered: an Al-Mg-Zn alloy with 3.0 mass% Zn and an Al-Mg-Zn-Cu alloy with added Cu. Tensile and fatigue tests were conducted to assess the alloy’s strength characteristics. The results of the tensile tests revealed a decrease in both yield strength and tensile strength with a decrease in the Mg content. Conversely, the addition of Cu resulted in improved yield and tensile strength. In the fatigue tests, a reduction in Mg content corresponded to an enhancement in fatigue strength, while an increase in Cu content led to a reduction in the fatigue strength ratio. To elucidate the observed strength improvements associated with decreased Mg and increased Cu content, a fracture toughness test was conducted. The Mg3.5-Cu1.0 alloy exhibited the highest stress intensity factor among the tested materials, providing further insights into the mechanism underlying the strength enhancement.

  • Slim DJEBIEN, Masahiro NISHIDA, Yunhe WU, Masanobu MURATA, Ziyi SU
    原稿種別: research-article
    論文ID: 24-0009
    発行日: 2024年
    [早期公開] 公開日: 2024/06/13
    ジャーナル フリー 早期公開

    Stress triaxiality is a well-established factor influencing material failure, particularly after elongation. Its significance is evident in its widespread use among damage accumulation models. In this study, we aim to analyze the post-necking behavior of thin metal sheets, specifically A2024-T3 aluminum alloy sheets. Such behavior is explored across a spectrum of stress states, ranging from shear to biaxial conditions. To ensure the robustness of the findings, experiments were conducted on three different lots of the same designated appellation, carefully considering the subtle microstructural variations. The data was meticulously gathered through localized fracture area analysis, employing digital image correlation techniques. Stress triaxiality was directly calculated from the experimental data. Notably, this study offers normalized data using a specific specimen shape, which is particularly valuable in scenarios where conducting an extensive array of experimental tests may be difficult. Based on the results, the overall shape of the fracture locus was effectively confirmed. Moreover, this study provides valuable insight on the influence of microstructure on the fracture locus. Finally, parameters essential for numerical simulations were determined.

feedback
Top