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Article type: Cover
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Cover1-
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Article type: Cover
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Cover2-
Published: December 30, 1974
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Article type: Appendix
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App1-
Published: December 30, 1974
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Shoichi NAKAMURA, Kimio SAITO, Shigeru ASAI
Article type: Article
Pages
1-12
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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In order to study the hydrodynamic pressure on ship's hull travelling in regular head waves, model experiments have been carried out with two models of a container ship and an ore carrier. The following three kinds of experiments have been performed to investigate the components of the hydrodynamic pressure. (1) Experiment I : Measurement of the hydrodynamic pressure acting on a free running model in regular head waves. (2) Experiment II : Measurement of the hydrodynamic pressure acting on a restrained model in regular head waves. (3) Experiment III : Measurement of the hydrodynamic pressure acting on a model which is forced to oscillate sinusoidally in calm water. The results of each experiment are compared with those of theoretical calculation based upon the ordinary strip method and the validity of the calculation method to estimate the hydrodynamic pressure is discussed.
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Kiyoshi TERAI, Hiroyuki MATSUMURA, Yoshinari IWAMURA, Hiroyoshi NAGAI
Article type: Article
Pages
13-21
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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The use of thick or special materials in marine structures has been recently increased under the requirement of high operative efficiency. However many practical problems in the conventional welding of these materials are not always controlled. Electron beam welding process is expected to be hopeful because of its high power density (10^4-10^5 times in comparison with conventional arc welding). The purpose of the present investigation is to examine weldability of HY-90 steel and 9% Ni steel used in marine structures by electron beam welding and also to investigate the possibility of its application to the marine structures. Consequently, HY-90 steel and 9% Ni steel were welded nicely by electron beam and several several practical processes of the application to marine structures were proposed.
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Minoru SAKAO
Article type: Article
Pages
23-38
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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A ducted propeller of a large stout ship operates in the non-uniform wake. Therofore, on such a ducted propeller, there exist many practical problems which are not only in propulsive performance but also in cavitation erosion, vibration forces and so on. However, very sophisticated calculations using the unsteady lifting surface theory are necessary for the exact analysis of these problems and this does not seem to be practical. From this point of view, the author has attempted to analyse these problems by a simple calculation method based on a bold assumption. In this paper, as the first part of the analytical approach, calculations on the flow around a symmetric ducted propeller in the uniform wake are described.
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Matao TAKAGI, Katashi TAGUCHI, Ryusuke HOSODA, Ryoji MANNO
Article type: Article
Pages
39-48
Published: December 30, 1974
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A calculation of normal forces acting on the rudders behind some typical ships is performed to clarify the possibility of the stabilization of the manoeuvrability in a ship compared with the model. The effects of the propeller slip-stream and the drift angle of the ship are taken into account. The calculation method is based upon the linear vortex line theory both for the rudder and the propeller. When the wake of a ship is large and the ratio of the rudder height to the diameter of the propeller is large, a possibility of the larger turning moment by the rudder in a ship compared with the model is shown.
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Hirokichi OGASAWARA, Katsuhiko YOSHIMITSU, Masami OKUNO
Article type: Article
Pages
49-58
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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While ship repairing industry has advantages of long business life cycle and stable profit rate which are characteristically seen in good business line, it also has some disadvantages, such as small turnover ratio to initial investment, high labour cost percentage in total cost make-up which makes the industry always liable to labourers' wage raise, and great fluctuation of aggregate labour hours day by day, which is difficult to be levelled due to short and limited working time till completion in infinite variety of kinds of repairs of many ships to be worked at a time. The writers, using simulation methods, studied repair yard operations on, in particular, 1) adequate numbers of docks and quays to be invested (which requires huge investment), 2) consolidated use of plural docks and quays to maintain high efficiency of their operations under placed condition, 3) mobility reservation in repair organization for constant and prompt compliance with orderers' needs (which serves directly for a good relationship with orderers), 4) correlation between the number of docks and levelling of aggregate labour hours. In this paper the contents and conclusions are introduced of which the authors wish to interest the readers.
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Ikuo UEMURA, Nobumi TANIMOTO, Kunihiro YOSHIKAWA, Toshio YAMAUCHI, Mas ...
Article type: Article
Pages
59-66
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Recently, shipyards in Japan are devided in two types, new gigantic and old. In new shipyards, they construct oil tankers of rather same type with new effective equipments under simple production system, and in old shipyards, they construct many kinds of ships with old equipments and man-power under a complex construction system. In this report, the authors introduced an example of a new system for loading planning of block assembly by computer in old shipyards. First, many problems existed and examples of improvements in assembly yards were introduced. Next, the new method for loading planning and input-output informations were described. Last, the procedure for planning of final block assembly schedule after manual smoothing of output data were introduced.
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Kohichiro NOHMI, Kohshiro KITADA, Yoshiki OKANO
Article type: Article
Pages
67-79
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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The super automated ore/oil carrier, M. S. Ohtsukawa Maru, was completed in September, 1972. She is equipped with a central computer controll system which consists of a cargo oil and water ballast handling system, navigation system, loading calculation system, etc. After the completion of the ship, a committee was organized by the shipowners, the shipbuilders and the subcontractors in order to investigate the problems in actual operation of the computer system for more than one year. The cargo oil and water ballast controll system, which was a main feature of the computer system, successfully controlled the oil loading and unloading operations which had no same pattern during the investigation period, and proved practical flexibility as intended at the design stage. The navigation system and loading calculation system also obtained high appreciation of the crew. This paper summarizes the results of the investigation of the committee, and includes the records of improvements, troubles and evaluations of softwares and hardwares as well as the maintenance works done on board, which wi11 be useful for the planning of the computer system in future.
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Hideo FUKUDA
Article type: Article
Pages
81-86
Published: December 30, 1974
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Improvement and stabilization of the accuracy in cutting hull component parts form the basis for increasing accuracy and efficiency in the hull construction. These studies were begun around 1955 with the aim of developing an automatic flamecutting system in order to eliminate errors in cutting hull component parts. Optically controlled flamecutting machines were introduced at the Innoshima Shipyard in 1956 to eliminate errors caused by the conventional manual marking and manual flamecutting. Then, numerically controlled flamecutting equipments were introduced and put to practical use at the Sakai Shipyard in 1966 in order to eliminate errors peculiar to optically controlled flamecutting. The software HIZAC was developed for the preparation of numerical data necessary for numerically controlled flamecutting. Further, computer controlled flamecutting system was developed in 1972 in order to comply with various kinds of higher technical demands, which was applied to the newly constructed Ariake Shipyard in Kumamoto Prefecture in 1973. Finally, a series of studies have been made on the improvement of quality and production control of hull construction, based on increased accuracy of hull component parts.
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Eiichi KITAMI, Mikio FUKUCHI, Shinichiro KUDO, Masaharu TAKAGI, Hiroka ...
Article type: Article
Pages
87-94
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Recently, at modern pipe shops in shipyards, welding mothods and facilities are so much well developed that various kinds of automatic and/or semi-automatic welding machines are utilized, up to 80∼90 % of all pipe welding. However, automatic welding is mainly applied on straight pipe/flange welding, and welding for complicated curved and long pipes is performed by hand. Authors intended to automize pipe welding in this field and to apply a new idea to make the welding torch turn around the flange to be fitted on the end of pipe. The main works in this paper are as follows. 1) Study of suitable welding condition at all position to fillet welding around pipe frange. 2) Selection of suitable mechanism to enable good welding beads for the above conditions and development of "All position automatic welding machine for fillet weld of pipe flange".
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Ichizo TAMAKI, Hiroshi KITASHIMA, Ryoichi NISHIDA, Toshiaki MATSUMOTO
Article type: Article
Pages
95-100
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Discharging oily water from the ship, especially from the tanker, is now very serious problem and is going to be strictly restricted. Under these circumstances, it is expected that oily water separator of big capacity, suitable for large tanker, be put into practical use. Authors describe about a newly developed oily water separator which is successfully provided on the motor tanker "Takakurasan maru". The authors also investigate correlation of oil separation performances between experimental plant at laboratory, land use and marine use, by analysing their operation results.
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Akira MASUMOTO
Article type: Article
Pages
101-111
Published: December 30, 1974
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Guide wire system is a simple method for cargo handling between floating platform and drilling part of remote-controllable deep sea oil drilling units, which consists of a cage and guide wires connected with the auto-tension unit on the floating platform at the upper end and the drilling unit on the sea bed at the lower end. It is considered that this system has some problems with the use of the system in waves and tides as follows. (1) Tangle of the guide wires themselves. (2) Tangle between the guide wires and the cables or anchor chains of the floating platform. (3) Attack angle of the cage to vertical line near the sea bed is extremely large or not. Scale model test and simple theoretical calculations were made to solve the above stated problems and to obtain the data for design. From this study, following points were made clear. (1) As the natural period of guide wires is very large (above 10 sec. in actual case), tangle of the guide wires does not occur in this case. (2) Basic design data of the system may be predicted from the simple theoretical calculations.
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Hiroyuki SADAKANE
Article type: Article
Pages
113-118
Published: December 30, 1974
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The present report deals with a transient motion in symmetric rolling with very large amplitude. A A-ψ plane is selected to study the transient motion. Equation of motion (1) can be transformed as (9), where A is a rolling amplitude and ψ is a phase difference. The motions nearby singular points and jump motions are obtained from equations (14) and (20) respectively. The calculations sufficiently explain the results of experiments. As far as the transient motions is slow, the present treatment to non-lincar equation is useful.
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Shigeru AKAZAKI
Article type: Article
Pages
119-121
Published: December 30, 1974
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If a force F is applied to a body through a distance x, then the work done W by the force is defined as W=Fx. Newton's second law of motion states that if a force F is applied to a body of mass M, the body will undergo an acceleration α, according to the relation F=Mα. Thus the work done is just the difference in the value of the kinetic energy function 1/2MV^2, evaluated at the final and initial positions. Here V is the velocity of the body. It had always been thought that the mass of an object was basic to the body and in fact was an absolute constant. In Einstein's theory it is found that the mass of an object is dependent upon the travelling velocity. In disscussing the kinetic energy of a moving mass we did not take account of changes in the mass, that is, we discussed the case where the velocities are much less than the velocity of light and the increase in mass is negligible. In author's theorem it is found that if a constant gyrating moment Pl is applied on a vertical axis of midship through an angle from 0 to 1 radian, the ship will undergo an angular acceleration ω, according to the relation Pl=I〓 ω. Here I〓 is the moment of inertia for the sum of the ship's mass and the added gyrating water mass on the vertical axis of midship. But a water mass stuck to the ship which is a part of the added gyrating water mass is dependent upon the angular velocity ω, thus the time function of ω is the outcome of what has been inversely proportional to the time function of increase in mass. It is found that the kinetic energy of the gyrating ship is 0.72 I〓ω^2. The kinetic energy of a turning ship is 0.6 m_3I_0ω^2. Here I_0 is the moment of inertia for the sum of the ship's mass and the added gyrating water mass on the pivoting point of ship. m_3 is the coefficient of turning virtual moment of inertia. 0.6 is the mean coefficient of kinetic energies of turning ships.
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Yoji HIMENO, Taketoshi OKUNO, Shigeru HAYASHITA, Norio TANAKA
Article type: Article
Pages
123-131
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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The problem of a steady surface wave in a circulating water channel is discussed in this paper mainly concerning its effects on the resistance of a ship model and also the relation between the form of a wave suppressor located at the outer edge of the nozzle and the steady wave. The resistance component of Froude-Krlov force working on the ship model in a steady wave is calculated using Motora's approximate method and the diffraction force using slender body theory. The comparison of these values with the measured shows that Froude-Krylov force plays an important role about the resistance variation of a ship model in the steady wave. The form of the wave suppressor is found to have a linear relation to the steady wave.
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Mitsuhisa IKEHATA, Nobuo NAGAMATSU, Kazuyuki HAYASAKI, Akihisa KOKUMAI ...
Article type: Article
Pages
133-149
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Automatic tank test system has been developed at Akashi Ship Model Basin, improving the efficiency of experiment, repeatability of test data, and the accuracy of measured value. This system is connected on-line with measuring instruments and driving device of the towing carriage, so that driving of the towing carriage, measuring, analyzing and plotting are automatically controlled by on-line program. In this paper concept of its system planning is described.
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Takeshi HORIKAWA, Hiroshi NAKAMURA
Article type: Article
Pages
151-162
Published: December 30, 1974
Released on J-STAGE: March 30, 2018
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Machine parts and structures are subjected to irregularly varying loads. It is very important to predict fatigue life of strength members under irregularly varying loads, and fatigue strength design has also become very important from the point view of security and economy. Random loads are classified into two parts ; one is a narrow band and the other is a wide band random wave. The authors have conducted fatigue tests under varying stress amplitude for the narrow band random wave, and under superimposed stress for the wide band random wave. In this paper, fatigue tests on four kinds of superimposed stress wave and varying stress amplitude were conducted with smooth specimen made from S35C carbon steel under axial loading. The experimental results under the superimposed stress wave and the varying stress amplitude were compared with each other. The faitgue life under the superimposed stress wave were in good agreement with the life under the varying stress amplitude test.
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Yoshikazu MATSUURA, Kenji ARIMA
Article type: Article
Pages
163-175
Published: December 30, 1974
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This paper presents a calculation method of natural frequencies of an elastic body vibrating in water. In the analysis using added virtual mass, it is necessary to use the actual mode shape in order to estimate accurately the added virtual mass. In this paper, the modified J-values for ellipsoid of revolution, circular cylinder and elliptical cylinder are derived by using actual mode shapes obtained from experiments. Calculated natural frequecies obtained by this method are in good agreement with those by model tests. Furthermore, another calculation method on coupled vibration of an elastic body and water is presented using the Rayleigh-Ritz method. This method is shown to be an effective tool for the analysis of flexural vibration of an elastic body immersed in water with a high accuracy.
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Article type: Appendix
Pages
177-179
Published: December 30, 1974
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Article type: Appendix
Pages
App2-
Published: December 30, 1974
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Article type: Appendix
Pages
App3-
Published: December 30, 1974
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Article type: Cover
Pages
Cover3-
Published: December 30, 1974
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