Journal of High Pressure Institute of Japan
Online ISSN : 1347-9598
Print ISSN : 0387-0154
ISSN-L : 0387-0154
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Original Paper
  • Tomoya OHE, Masahiko MITSUMOTO, Yukinori FUJIGIWA, Takayoshi INOUE, Ak ...
    2020 Volume 58 Issue 3 Pages 138-151
    Published: 2020
    Released: July 02, 2020
    JOURNALS FREE ACCESS
    This paper describes the results of development regarding a large flat bottom cylindrical liquid hydrogen tank. Since a liquid hydrogen tank is required 10 times higher thermal insulation performance than an LNG tank, thermal insulation structure is the most important issue. In the roof and the shell part, mounting construction method of the multilayer insulation that enables high workability and hardly deteriorating thermal insulation performance has been devised. In the bottom part, the hollow sectional GFRP support that copes with both high buckling strength and high thermal insulation performance has been devised. Regarding the anchor strap, high thermal insulation performance has been achieved by using CFRP member maintaining high tensile rigidity and high tensile strength. The calculated boil off gas rate of 10,000m3 liquid hydrogen tank applying devised thermal insulating structures has been less than 0.1%.
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  • Takatoshi HIROTA, Naoki OGAWA, Hiroyuki SAKAMOTO
    2020 Volume 58 Issue 3 Pages 152-160
    Published: 2020
    Released: July 02, 2020
    JOURNALS FREE ACCESS
    A reactor pressure vessel is made of ferritic low alloy steel, which exhibits transition of ductile to brittle region as temperature decreases. Neutron irradiation enhances tensile property and decreases fracture toughness in the beltline region of the vessel which surrounds reactor core. The Japan Electric Association code, JEAC 4206-2016 specifies a procedure for assessment of a reactor pressure vessel integrity against pressurized thermal shock (PTS) events considering irradiation embrittlement of the beltline region, which postulates a semi-elliptical flaw (10 mm in depth and 60 mm in length) beneath the cladding. JEAC 4206-2016 prescribes a simple method for calculating stress intensity factor of the flaw, taking into account the effect of yielding of cladding. In this paper, the calculation procedure for a stress intensity factor of a semi-elliptical flaw beneath the cladding without employing JEAC 4206-2016 method to reduce excess conservatism is investigated. One option is employing 3D finite element analysis and the other option is to change plasticity correction factor to newly proposed correlation.
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  • Satoshi KOBAYASHI, Toshiko OSADA
    2020 Volume 58 Issue 3 Pages 161-170
    Published: 2020
    Released: July 02, 2020
    JOURNALS FREE ACCESS
    Static tensile, tensile-tensile fatigue and residual strength tests were performed on the unidirectional high and intermediate moduli carbon fiber reinforced plastic (CFRP) specimens. The damage mode for intermediate modulus CFRP was splitting in both static and fatigue tests. On the other hand, fiber breakage was dominant damage mode for high modulus CFRP. The slope of the S-N curve was larger for the intermediate modulus CFRP than that for the high modulus CFRP because of the matrix fatigue damages. The results suggested higher durability for high modulus CFRP. From the residual strength tests with acoustic emission measurement, Kaiser effect was not satisfied at the stress level of the fatigue test for the specimen with lower residual strength and the possibility to detect the microscopic damage in the CFRP with acoustic measurement was indicated.
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  • Mitsuo NAGAO, Osamu YOKOTA, Yuto YAMADA
    2020 Volume 58 Issue 3 Pages 171-179
    Published: 2020
    Released: July 02, 2020
    JOURNALS FREE ACCESS
    The experimental model is a method for carrying out load and unloading in air jet on the surface of the flexible materials. It is possible that this method carries out load and unloading in a moment, and dent deformation which arose on the surface can be measured in the laser beam in a moment. In addition, the aging variation of shape and dimension of the dents can be measured also. In this study, the fact of the following has done using creep meter and experimental model. Under the monotonic step load, three behaviors were shown elastic behavior, retarded elasticity behavior and viscous flow from the instant dents deformation. The formulation of dents depth under the creep load was able to be formulated. In addition, the experimental result under the step load repeatedly agreed with calculation result using the principle of superposition.
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