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Article type: Cover
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Cover1-
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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Article type: Cover
Pages
Cover2-
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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Article type: Appendix
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App1-
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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Yoichi HARA
Article type: Article
Pages
1-12
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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The plastic anisotropy of ship hull structural steel was carefully investigated and was clarified to have the property of normal anisotropy. Further it was demonstrated that the Hill's plastic potential for orthotropic material is applicable to this normally anisotropic material. Various characters of normally anisotropic plates were deduced theoretically, such as the stress-strain rate relation, the yield function, the plastic instability of extension, etc. As a practical problem of normally anisotropic plates the maximum tensile load of plates with cutouts or notches was examined and a comparison was made between a theory and experiments. Simultaniously the effect of the normal anisotropy on the muximum load was brought to light.
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Yoshikazu MATSUURA, Hazime KAWAKAMI
Article type: Article
Pages
13-26
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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In the first, second and third reports the main features of coupled torsional and flexural vibration of a free-free uniform bar with open cross section were investigated theoretically and experimentally It was shown that in order to calculate the natural frequencies correctly the effects of torsional rigidity GJ and shear deflection should be considered, and that when a bar had transverse bulkheads the effect of transverse bulkheads could be treated with the equivalent torsional rigidity GJ. In this report, theoretical and experimental studies are made, based on the above results, on the coupled torsional and flexural vibration of a free-free uniform bar with open cross section having closed section parts at both ends, which can be regarded as a simplified model of a ship with large hatch openings. It is found that the natural frequencies and the modes of vibration of the above-mentioned bar can be calculated by the matrix method with reasonable accuracy in the lower modes of vibration by regarding the closed section parts as rigid bodies, if their length are small in comparison with the length of the open section part.
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Tomoyuki HIROWATARI, Kohei MATSUMOTO, Hiroaki KADO
Article type: Article
Pages
27-38
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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There are many kinds of tanks placed in the engine room of a large ship, and damages of these tanks caused by vibration are tending to increase as powers of engines grow. In order to prevent such troubles, it is necessary to estimate the natural frequencies of tanks precisely at the design stage and to avoid their coincidence with the frequencies of vibration exciting forces. The authors have carried out some theoretical and experimental investigations into the vibration of tank, and obtained a method of calculation of the natural freqencies taking into account effects of coupling vibration of side walls. This calculation method is applied to two tanks; a model tank and an actual on board a ship. The results are compared with the experiments, and the following features are observed. (1) For the model tank in empty condition, the calculated natural frequencies coincide well with the experimental. (2) The lowest natural frequency obtained by the tests for the model tank in full water condition is 61% lower than the one in empty condition, and virtual water coefficient derived from this experiment is rather higher than the calculated by the use of Prof. Kito's formula. (3) For the actual tank, the lowest natural frequency from the experiment is very much lower than the calculated. An analysis is made on this problem and it becomes clear that the observed lowest frequency is due to a rocking motion of the tank.
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Matao TAKAGI, Akihisa KOKUMAI, Masami HIKINO
Article type: Article
Pages
39-42
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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Method of "steering quality indices" K and T is very convenient for ship designers to estimate roughly the manoeuvrability of a ship. These indices are, however, indefinite and even meaningless for the low course-stability ships. In this paper it is stated that K/T almost determines the manoeuvrability of the low course-stability ships, and new "course-changing test" is proposed in order to obtain K/T directly. Another test is necessary to know the course-stability. Reverse spiral test is suitable for this purpose, because it is surer and takes less time than usual. But it is still troublesome to do the test for every ship. Therefore new method called "decay test" is proposed in this paper.
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Ichiro TANAKA, Yoji HIMENO
Article type: Article
Pages
43-47
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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A method is described for calculating velocity distribution in the turbulent boundary layer with pressure gradient, utilizing Pohlhausen's method to solve laminar flow problems. The calculated velocity profile in the boundary layer is given in Eq. (5), which shows the velocity is expressed as the sum of two terms : one determined by the shearing stress at the wall and the other by the pressure gradients. The integration of the velocity profile and some calculation following it lead to a new formula for the local frictional coefficient, Eq. (14). Several features concerning the effect of pressure gradients on the boundary layer characteristics are also discussed.
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[in Japanese]
Article type: Article
Pages
48-51
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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[in Japanese]
Article type: Article
Pages
52-56
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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Article type: Appendix
Pages
57-60
Published: June 30, 1969
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Article type: Appendix
Pages
App2-
Published: June 30, 1969
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Article type: Appendix
Pages
App3-
Published: June 30, 1969
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Article type: Appendix
Pages
App4-
Published: June 30, 1969
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Article type: Appendix
Pages
App5-
Published: June 30, 1969
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Article type: Appendix
Pages
App6-
Published: June 30, 1969
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Article type: Cover
Pages
Cover3-
Published: June 30, 1969
Released on J-STAGE: February 25, 2018
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