圧力技術
Online ISSN : 1347-9598
Print ISSN : 0387-0154
ISSN-L : 0387-0154
53 巻, 2 号
選択された号の論文の5件中1~5を表示しています
論文
  • 吉田 聖一
    原稿種別: 論文
    2015 年 53 巻 2 号 p. 56-68
    発行日: 2015/03/25
    公開日: 2015/05/01
    ジャーナル フリー
    Powerful tsunami attacked to the northeast coast of Japan due to the 2011 Great East Japan Earthquake occurred on March 11, 2011 with a moment magnitude 9. 0. There are many fishing ports along the coastal line. Several small aboveground storage tanks (ASTs) storing the fuel for fishing boats were installed at the fishing ports. Tsunami moved the ASTs and overturned them. Some of them leaked oil and sank to sea. On the other hand, although both small ASTs with full liquid and large ASTs did not move, they were subject to external pressure of the tsunami. This paper presents the bifurcation buckling analysis of shell plates in large ASTs by the axisymmetric shell finite element method. The influence of shell thickness, tank height, tank diameter and annular thickness to the buckling characteristics under external liquid pressure due to tsunami is described.
  • 浦部 吉雄
    原稿種別: 論文
    2015 年 53 巻 2 号 p. 69-78
    発行日: 2015/03/25
    公開日: 2015/05/01
    ジャーナル フリー
    In order to rationalize the low cycle fatigue evaluation of elbow piping subjected to in-plane cyclic bending displacement, an advanced revised universal slope method is proposed. In the proposed method, the coefficient of the first term of the fatigue life equation which resembles Manson's equation is expressed by parameters of the multi-axial degree, the tensile strength and the fracture strength. Also, the coefficient of the second term is expressed by the multi-axial degree, the fracture ductility and the minimum fracture ductility under the maximum multi-axial degree. Here equivalent strain range is used for the fatigue life estimation. The previously carried out pipe elbow test data were reanalyzed using the proposed method. As the result, the experimentally obtained fatigue lives had considerably good coincidences with the predicted fatigue lives by the proposed method. Application of the proposed method is also discussed.
  • 名嘉 海人, 真壁 朝敏, 宮崎 達二郎
    原稿種別: 論文
    2015 年 53 巻 2 号 p. 79-87
    発行日: 2015/03/25
    公開日: 2015/05/01
    ジャーナル フリー
    Some simple technical methods for arresting crack growth have been proposed to prevent the fatigue failure of machinery. Drilling a stop-hole at the crack tip and attaching a patch at crack sites are typical methods for arresting crack growth. In this study, in addition to the drilling of a stop-hole, a crack arrester was attached across the crack to extend the fatigue life. In particular, a plate specimen having portions with different thicknesses was used in a push-pull test, and three types of crack arresters were prepared. The effect of the crack arrester on the prevention of crack growth when a crack is initiated in plates with different thicknesses was considered.
  • 岡野 成威, 宮坂 史和, 田中 学, 望月 正人
    原稿種別: 論文
    2015 年 53 巻 2 号 p. 88-95
    発行日: 2015/03/25
    公開日: 2015/05/01
    ジャーナル フリー
    Stress corrosion cracking (SCC) has recently been observed in the nickel base alloy weld metal of dissimilar pipe joint used in pressurized water reactor (PWR) . Temper bead technique has been developed as one of repair procedures against SCC applicable in case that post weld heat treatment (PWHT) is difficult to carry out. In this regard, however it is essential to pass the property and performance qualification test to confirm the effect of tempering on the mechanical properties at repair welds before temper bead technique is actually used in practice. Thus the appropriate welding procedure conditions in temper bead technique are determined on the basis of the property and performance qualification testing. It is necessary for certifying the structural soundness and reliability at repair welds but takes a lot of work and time in the present circumstances. Therefore it is desirable to establish the reasonable alternatives for qualifying the property and performance at repair welds.
    In this study, mathematical modeling and numerical simulation procedures were developed for predicting weld bead configuration and temperature distribution during multi-layer repair welding process by temper bead technique. In the developed simulation technique, characteristics of heat source in temper bead welding are calculated from weld heat input conditions through the arc plasma simulation and then weld bead configuration and temperature distribution during temper bead welding are calculated from characteristics of heat source obtained through the coupling analysis between bead surface shape and thermal conduction. The simulation results were compared with the experimental results under the same welding heat input conditions. As the results, the bead surface shape and temperature distribution, such as Acl lines, were in good agreement between simulation and experimental results. It was concluded that the developed simulation technique has the potential to become useful for accurate prediction of weld bead configuration and temperature distribution at repair welds.
  • 土田 豊
    原稿種別: 論文
    2015 年 53 巻 2 号 p. 96-101
    発行日: 2015/03/25
    公開日: 2015/05/01
    ジャーナル フリー
    Ebihara et al. had reproduced hydrogen desorption curves by McNabb-Foster diffusion equation with two types of hydrogen traps together with interstitial hydrogen. These curves were subjected to peak separation through Gaussian distribution for two contrasting cases; (a) sufficient amount of hydrogen with 150°C (423K) main peak and280°C (553K) sub-peak simulating soaking in NH4SCN solution, and (b) insufficient amount of hydrogen with 280°C (553K) main peak and 150°C (423K) sub-peak simulating exposure to CCT cycles. The amounts of trapped hydrogen by Gaussian separation were well consistent to those by McNabb-Foster equation in those two cases. Further, Gaussian distribution could separate interstitial hydrogen separated as a unique peak. This peak corresponding to interstitial hydrogen can be understood by random walk model where hydrogen atoms jump between interstitial sites to trap sites randomly. Distribution of hydrogen trapped by 150°C (423K) peak in the case (b) was slightly different from Gaussian distribution through the effect of 280°C (553K) trap, but it would not matter, considering the possible error in TDS measurement.
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