Journal of High Pressure Institute of Japan
Online ISSN : 1347-9598
Print ISSN : 0387-0154
ISSN-L : 0387-0154
Volume 54, Issue 6
Displaying 1-4 of 4 articles from this issue
Original Paper
  • Takashi OHNO, Nobuyuki KOBAYASHI, Osamu FURUYA, Kenji OYAMADA
    2016 Volume 54 Issue 6 Pages 266-276
    Published: November 25, 2016
    Released on J-STAGE: December 27, 2016
    JOURNAL FREE ACCESS
    Significant fire and explosion accident on spherical tanks for Liquefied Petroleum Gas (LPG) storage was induced by the strong ground motion of the 2011 Great East Japan Earthquake. Steel pipe braces were broken due to the strong seismic inertia force, and then buckling of support legs was occurred. To prevent recurrence, reinforcing the intersection of braces was needed. The authors investigated the fracture mechanism of spherical tank and the effectiveness of reinforcement by Finite Element Analysis and shaking table test. However, the static relation between force and displacement or strain is not clear yet. In this study, we conducted static tests using a plane of structure of spherical tank. From the test results, it was concluded the effectiveness of reinforcement of the pipe braced supporting frame of a spherical tank as follows; (1) In a case of brace intersection was reinforced, the rigidity of the supporting frame increased. (2) Fracture mechanisms of the steel pipe brace was different from without reinforcement to with reinforcement.
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  • Takeshi OGAWA, Shota HASUNUMA, Shota WATANABE, Naoki SOGAWA, Toshihiko ...
    2016 Volume 54 Issue 6 Pages 277-288
    Published: November 25, 2016
    Released on J-STAGE: December 27, 2016
    JOURNAL FREE ACCESS
    Hydrogen gas container is one of the critical components for fuel cell electric vehicle (FCEV) , which is expected for CO2-free personal transportation. In order to choose an appropriate material for its metal boss or liner, crack growth resistance should be evaluated for various aspects such as stress corrosion cracking (SCC) and fatigue crack growth (FCG) in any environments for the purpose of commercial vehicle use. In the present study, characteristics of SCC and FCG in humid air and in NaCl solution were obtained for aluminum alloys of A6061, A6066 and A6351 with attention to the testing methods. Threshold K value for SCC,KISCC , was determined by two types of tests under K-increasing and D-constant (K-decreasing) conditions, where Kand Dare stress intensity factor and specimen displacement, respectively. In the former test, partial unloading was conducted at every 1000 s in order to monitor the crack growth by unloading compliance method. Crack growth rate of SCC, da⁄dt, is enhanced by the partial unloading in the K-increasing test, while measurable da⁄dt is much smaller in the D-constant test. KISCC of A6351 is much lower than those of A6061 and A6066 in humid air, while it was not able to determine in NaCl solution due to the anodic dissolution for all the materials. Grain size indicates minor influence on SCC tested by the K-increasing test. Conservative FCG characteristics are obtained by Kmax-constant test, where the maximum stress intensity factor,Kmax , should be less than the KISCC in order to avoid the SCC contribution. Crack growth rate of FCG, da⁄dN, is similar in humid and laboratory air environments, while it is higher in NaCl solution. Larger grainsized materials show lower da⁄dN both in humid air and in NaCl solution.
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