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Article type: Cover
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Published: September 25, 1990
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Article type: Index
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Published: September 25, 1990
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Article type: Index
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Published: September 25, 1990
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Hisashi NOBUKAWA, Michio NAKATO, Yasuhiko OSAWA
Article type: Article
Pages
1-9
Published: September 25, 1990
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RIVERSEA is a new idea ship. When she starts from a shallow river in down town, she is a monohull and when in high speed sailing at sea, she metamorphoses to a catamaran by lifting up mechanism of her cabin. The first work of RIVERSEA design was model ship experiments in a high speed circulating water channel so as to obtain the informations of sailing conditions i.e. trim, sinkage, wave making and spray. At the same time, the operation of hydrofoils in the catamaran condition were investigated. These results and inforations were directly taken in to the inital design. The second work was to determine the pricipal particulars and to drow a rough general arrangement. In this stage, the investigation of mechanism for lift up/down of her cabin and fixing it were carried out in parallel. This was ons of the most difficult work of the project. The third was to certify the strength of RIVERSEA and to estimate the vibration phenomena. This report describes these design works of each step, together with successful results of sea trial of RIVERSEA.
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Mitsuo KISHI, Masakazu ARIMA, Tomoki MAEDA
Article type: Article
Pages
11-17
Published: September 25, 1990
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On account of the industrial standard or of the inherent characteristic of the design variable, most of practical design optimizations are considered as combinatorial optimization problems. Recently, Hopfield and et al. showed that some combinatorial optimization problems can be programmed and solved on artificial neural network system minimizing the quadratic energy function. In this study, an algorithmic procedure with neural networks for solving combinatorial optimization problems is proposed. The method attains good feasible solutions by systematically changing the Lagrange multipliers for the constraints in the problem. The proposed method can be applied to both linear and quadratic programming problems with discrete control variables. Numerical example for the optimum design of a frame structure is provided to illustrate the basic properties and applicability of the proposed method. The method is also applied to the optimum design of midship section in a general cargo ship.
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Kazuhiko HASEGAWA, Mato HATTORI
Article type: Article
Pages
19-26
Published: September 25, 1990
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Handling of visual information is one of the most human-oriented problems. Though people can easily do it without any measurement or calculation, it is generally very difficult to treat it in computer application. In our previous studies, we have developed a method to perceive picture interference, and showed its applications. This method can be applicable to various automatic layout systems, in which a rule such as "set the object to an appropriate place without interfering other objects" is included. We have also proposed a concept of "spatial distance" for more human-like handling of visual information. In the present study, we have utilized the concept of "spatial distance" and proposed a method to understand the most "wide" place in the limited area. This method is applied to a case where three polygons are already placed in a given area. The system finds out the most suitable place for the fourth polygon to be placed without any instructions from human operator. After setting the polygon to the recommended place, the system again checks the "spatial distance" between the newest polygon and already-set polygons, and suggests to adjust the position of the newest polygon so as be equally apart from other adjacent polygons.
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Naoki TANABE, Yoji HIMENO, Nobuhiro BABA, Noboru UEHARA
Article type: Article
Pages
27-37
Published: September 25, 1990
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A new method is developed for obtaining an optimum body profile with minimum drag in two-dimensional viscous incompressible flows. The method consists of a combination of a numerical Navier-Stokes solver, an application of nonlinear mathematical programming technique, and a grid generation / deformation method. The pressure and friction drag components of a steadily advancing body of arbitrary configuration are evaluated from the finite - difference solution of the Navier - Stokes equations. The third - order accurate upwind differencing is used for the nonlinear terms and the time is advanced by the implicit Euler method to obtain a steady solution. Body profile is represented by a series of polynomials including determinate variables as coefficients. The feasible direction algorithm is applied for the nonlinear constrained optimization problem. Numerical tests are conducted to demonstrate the validity of this method.
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Yoji HIMENO, Shigeru NISHIO, Kenichiro TAKAMATSU
Article type: Article
Pages
39-47
Published: September 25, 1990
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An uncertainty analysis is applied to resistance test of a ship model, according to Performance Test Code of ASME, in which all possible error sources are listed, evaluated, and summed up with sensitivity coefficients to the final results. The uncertainty analysis for resistance test is divided into two steps. The first step is the analysis on measurement uncertainty itself, and the second is on the process of standardization of the test results. Through these analysis one can easily find main error sources and their routes of the error propagation. In the second step of the uncertainty analysis, i.e., in the analysis of the test results, new error sources come out from the processes of correcting measured data to a standard condition by use of empirical correction formulas, and of fitting data to some functions. These errors should also be analyzed, in accordance with the ordinary error propagation from the measured data to the final results.
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Taketoshi OKUNO, Eiji SAKAMOTO
Article type: Article
Pages
49-57
Published: September 25, 1990
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The present paper describes the method of flow field measurement using two visualized images which are recorded in a small time difference. The typical four methods, the so-called path-line method, the spatio-temporal derivative method, the correlation method and the two dimensional FFT method, are compared from the practical point of view. Then, the theoretical consideration of FFT method was made in the case that the images are not freezed completely, which called the image data with nois here. It is found that this nois always gives a error velocity vector. The simple method for excluding the error vectors is proposed. The relationship between FFT method and the correlation method is also shown. The correlation function is calculated using FFT, and used it in the two dimensional Fourier Transform Method. The more exact correlation method taking accout of gray level data of images is shown.
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Ryouzou HIRAKU, Toshio SUZUKI
Article type: Article
Pages
59-64
Published: September 25, 1990
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Tracer pathline images of flow field give us a great deals of information about the flow field and several methods were developed to obtain the velocity vector from these pictures. In this paper, a new technique is proposed in order to obtain the velocity vector from the pathline image photograph of the flow field. The summary is as follows. 1) Streamline directions are obtained from the use of the imaginary vectors of which arguments have twice the values of gradient vectors of brightness of the photograph. 2) The velocities are also obtained from the use of the imaginary vectors and the original gradient vectors in the small area of interest. 3) The two kinds of the flow field, uniform flow and the flow around a circular cylinder, are analyzed by this method and the good results are obtained.
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Susumu HIRANO, Shohei INATSU, Yoji HIMENO
Article type: Article
Pages
65-73
Published: September 25, 1990
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High-speed planing hulls support their weight by the dynamic lift, rather than the buoyancy as in case of displacement ships. The planing hulls, therefore, have a high-pressure region on the hull bottom, which gives rise to a water spray formation, spreading out in both sides of the hull. The spray is considered to be one component of the pressure drag. The present paper describes the results of observations of the spray configuration on prismatic planing-hull models. The flow velocity field on the spray and the flow flux are also measured to obtain the spray thickness and the momentum loss due to the spray. It is found that the spray resistance thus measured has a large part of the total pressure drag of the model hull.
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Makoto UCHIDA, Eiichi NISHIKAWA, Hideo KAMIYAMA
Article type: Article
Pages
75-80
Published: September 25, 1990
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It has become usual that the blade strength of a screw propeller running in the wake of ship hull is evaluated by taking into consideration of not only static blade stress but also the dynamic one. Recently Sasajima proposed a simplified method for estimating the dynamic blade stress. In this method, the distribution of the circulation the radial direction is represented by an apriori pattern. Therefore the method isn't able to be applied to the case of controllable pitch propeller of which circulation distribution varies with the blade angle. This paper proposes a modification of the simplified method by use of the blade element model in order to make it applicable to the case of the controllable pitch propeller, and investigates the validity of the proposed method by comparing with the measurement results of an actual controllable pitch propeller.
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Yasushi HIGO, Mun-Keun HA, Ping XU
Article type: Article
Pages
81-87
Published: September 25, 1990
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A procedure for calculating added resistance on a virtical circular cylinder in regular waves is presented. The linearized velocity potential for around a model is given by source distribution on discrete panels representing the body. Momentum relations, Maruo's theory, are used to derive general results in terms of Kochin function with the effect of line integral. These computational results in momentum theory show that the effect of line integral on added resistance cannot be neglected. At the same time, another evaluation of the drag force on the model is performed by integrating the pressure directly on the surface of the body. These analytical results for the model in head and following sea conditions are compared with experimental results.
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Ken TAKAGI
Article type: Article
Pages
89-98
Published: September 25, 1990
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The author had developed Rankine Soure Method for unsteady free surface flows in a recent paper. This method is applied for the calculation of added resistance of a ship in this paper. In order to confirm the validity of Rankine Source Method for the calculation of added resistance of a ship, influences of the artifice due to Rayleigh and the panelling of the free surface boundary on numerical precision are investigated, and numerical results are compared with a recent study about added resistance of a hemishere (Zhao et al.). The agreement between them is very good. The calculation of added resisitance of a blunt ship is done under the new free surface boundary condition which takes steady disturbances into account and the calculation is also done under the classical free surface boundary condition which does not take it into account. The compatatison with experimental results shows importance of effects of steady disturbances.
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Masakazu KAJI, Yoshikazu NISHI, Yoshio YAMAGAMI
Article type: Article
Pages
99-104
Published: September 25, 1990
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To respond to the needs for high speed transportation, hydrofoil vessel, which is supported partially or totally by the foil lift, has been widely investigated. As few studies have been made on its motions, the authors have studied this problem theoretically and experimentally. As a result of this study, it is pointed out that unsteady characteristics of the hydrofoil have to be included in the hydrodynamic coefficents of the motion equatios for predicting the hydrofoil vessel's motions. It is also confirmed experimentally that the lifting line theory is useful to calculate the unsteady characteristics of the three dimensional hydrofoil under free surface.
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Yoshiho IKEDA, Hiroshi TAKATA, Shinich ISHIHARA, Makoto SOEJIMA
Article type: Article
Pages
105-112
Published: September 25, 1990
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It is important for modern passenger ships to reduce seasickness of passengers. In the initial design stage of a passenger ship, its seakeeping quality should be evaluated. It is said that there are many reasons which make a passenger be in illness. The vertical acceleration among is considered to have the most significant effect on seasickness. Using the relationship between the vertical acceleration and percentage of vomiting passengers deduceted by O' Hanlon & McCauley, the seakeeping quality of a 6,000GRT cruise ship is evaluated in a regular head wave of 2m wave height in the present paper. The results show that the percentage vomiting is minimum at SS.3 and at it is maximum at the bow. The effects of the size of a ship, the cruising speed of a ship and anti-pitching fins are discussed in detail.
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Matao TAKAGI, Kimio SAITO, Hisafumi YOSHIDA
Article type: Article
Pages
113-121
Published: September 25, 1990
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We study the second-order currents and changes in local mean surface level induced by two-dimensional monochromatic radiation waves in experimental flume with a paddle type wave-maker. The second-order velocity potential in periodically steady state obtained as the long-time limit of a transient state, where arbitrary constants are uniquely determined. The second-order currents are proved to be totally canceled out by Eulerian Stokes drift in any section and thus mass conservationin the flume is hold.
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Matao TAKAGI, Kimio SAITO, Hisafumi YOSHIDA
Article type: Article
Pages
123-127
Published: September 25, 1990
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Following the previous paper, we study the second-order changes in local mean surface level induced by two-dimensional bichromaic radiation waves in an experimental flume with a paddle type wave-maker. The second-order velocity potential in the case of bichromatic waves consists of the steady terms of each wave component and the long-period terms which correspond to locked and free waves. From the numerical examples, it is found that the free-wave component plays an important roll in the evaluation of the local mean surface level and it is also shown that the most part of it is set down, but the higher part of it is set up.
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Shigeru KIMURA, Nobuhiro BABA, Yoji HIMENO
Article type: Article
Pages
129-138
Published: September 25, 1990
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A tidal current in Osaka Bay is studied by using the finite-volume solutions of the two-dimensional time-dependent Navier-Stokes equations. The discretization technique with the geometric conservation properties in generalized curvilinear coordinate systems is developed based on Vinokur's idea. The primitive variable formulation uses the volume fluxes across the faces of each computational cell and the pressure defined at the center of cell as dependent variables. The simultaneous iterative procedure is applied for time advancement of the primitive variables to satisfy the discretized mass-conservation equation. The computational results show that a tidal current flows through the west part of Osaka Bay, but that it does not almost affect the current along the east coast of the Bay. The pairs of circulating flows with opposite rotation are found in the tidal residual current near both Akasi and Kitan Straits. Another numerical experiment is carried out to investigate the possibility of current control. An example is presented in which a small artificial island causes a large-scale circulating current in the center of the Bay, the effect of which reaches the east coast of the Bay.
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Atsuhiko MORI, Shigeru NAITO
Article type: Article
Pages
139-144
Published: September 25, 1990
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The theory to absorb wave energy has already established by many researchers. Allthough, it is not so easy to build up the system which absorbs wave energy by external mechanism. Especially, it need many hours to make the values of spring and damping coefficients of the mechanism optimum. The paper shows the experimental results of wave absorption with a Voice-coil type linearmotor and, that the working hours to regulate the system can be reduced with it.
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Hajimu MANO, Hiroshi KAWABE, Kouji MASAOKA, Takafumi ITO
Article type: Article
Pages
145-156
Published: September 25, 1990
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When ship is a sagging condition, deck panels are applied compressive load. Compressive ultimate strength of deck panels is important as we consider about longitudinal strength. For heat affection when deck was built up by welding, deck panels are distorted and deflected. This iniitial deflection of deck panels reduce the compressive ultimate strength of the deck panels. In this study, at first we measured the initial deflection of about 450 deck panels. From these measurement we investigate shape and magnitude of initial deflection. We found various kind of initial deflection. We summarrize these results, and propose the standard shape of initial deflection and following equation of magnitude of initial deflection. ω_0/t=8×10^<-5>(b/t)^2 There are many welded lines on deck panels. Thirty five percent measured deck panels of the tanker contain welded lines. These panels have complex shape and large initial deflection. Compressive ultimate strength of these panels is lower than that of panels without welded lines. We calculate compressive ultimate stength of measured by F.E.M., and investigate the statistical characteristics of the compressive ultimate strength. Variations of yield stress and initial deflection are the most effective factors on the statistical compressive ultimate strength of the deck panels.
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Kohei MATSUMOTO, Hideyuki SHURI
Article type: Article
Pages
157-170
Published: September 25, 1990
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This paper presents an estimation method of natural frequency of superstructure. Accuracy of several exsisting empirical formula were examined by using newly developed database system of superstructure vibration. In order to obtain an accurate simple formula, some empirical formula having different parameters were derived from regression analysis by database. It is found that height of vibration layer introduced by Hirowatari's method gives the best accuracy as a parameter of empirical formula. However, accuracy of simple formula can not be expected that within 12% because these formula does not take into account complexity and variety of superstructure and coupled effect of ship hull vibration.
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Shinichi TAKAGAWA, Hisao TEZUKA, Kenji AKASAKA, Motohiro KITAGAWA, Yos ...
Article type: Article
Pages
171-176
Published: September 25, 1990
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"SHINKAI 6500" is the latest manned submergence research vehicle which is characterized by excellent research capability and the deepest submergence capability in the world. Through construction of the submersible, many excellent elemental technologies were established. The technology on viewports made of methacrylate plastic which are adopted as transparent boundary of the pressure hull is estabilshed based on such technologies. The authors have already established design and fabrication technologies on the similar viewports for manned deep submersibles through constructing 2000m deep submergence research vehicle "SHINKAI 2000" which has been constructed in 1981 and is currently in active. In the planning of the viewports for "SHINKA 6500" the authors designed them on the results of "SHINKAI 2000" and performed some experiments by using full-scale specimens to confirm its enough safety to apply to the pressure hull boundary of "SHINKAI 6500". Following conclusions were obtained from the results of the experiments and reliability for practical use has been clarified. (1) It has been found that fracturing pressure of the viewports is about 3500kgf/cm^2 and a safety factor above five is insured to the maximum working pressure 680kgf/cm^2. (2) The viwports have enough endurance ability to the design life of four years. (3) Enough safety is to be insured while the life-support time of 129 hr. (4) Impact strength of the viewports are about 1.8 times as strong as the ones for "SHINKAI 2000" which is already active under water and its validity is successfully confirmed.
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Shinichi TAKAGAWA, Hideyuki MORIHANA, Kouichiro SHIMODA, Yutaka YAMAUC ...
Article type: Article
Pages
177-185
Published: September 25, 1990
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The pressure hull of deep submergence research vehicle is an utmost important structure that secures the safety of crew members against the hydrostatic pressure in deep sea, and should be as compact in size and light in weight as possible in order to obtain easy operation and high maneuverability of the vehicle. In design and fabrication of the pressure hull, the application of high strength material which has reliable characteristic for practical use, of design method suitable for such material and fabrication procedure which satisfies the quality requirement of the highest degree have been encouraged. In the develoment of the 6500m deep submergence research vehicle "SHINKAI 6500", which is the latest submergence research vehicle following the 2000m deep submergence research vehicle "SHINKAI 2000" in Japan, the investigation in various fields was carried out in order to adopt titanium alloy, which has superior strength/weight ratio, for the pressure hull. The production procedure of heavy thickness and large size plate and forging material, and the fabrication procedure of the pressure hull were investigated by the fabrication of the full scale model made of titanium alloy and by material tests with specimens cut from the model. The collapse behaviour was examined by collapse tests using scale models of titanium alloy and by nonlinear behaviour analysis with FEM procedure. Finally, in order to confirm both the fabrication procedure and design method in total, the cyclic loading test and collapse test using scale model fabricated according to the procedure equivalent to that for the actual pressure hull. This paper presents the design and fabrication of the pressure hull of "SHINKAI 6500".
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Ken-ichi KITAURA, Yoichiro OKAMURA, Hiroo OKADA
Article type: Article
Pages
187-195
Published: September 25, 1990
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In this paper, as a basic study on the impact fatigue of ship and offshore structual members under wave induced loads, effects of static stress due to still-water loads and prestrain due to extreme-wave loads on impact fatigue strength of steel materials are investigated experimentally. Low-cycle impact fatigue tests for specimens systematically varying constant static stress and prestrain are carried out on three kinds of steel materials (SS41, S25C and S45C). From experimental results and theoretical considerations, conclusions are summarized as follows: (1) From the results of tests systematically varying static stress, it is found that the relations between the constant creep strain rate Δε_c (or plasticity strain rate Δε_c=Δε_c/T^^-), maximum impact stress σ^^-_<max> and fatigue life N_f are expressed by σ^^-_<max>/σ_B=S(Δε_c/ε_f)^β …(a) (Δε_c/ε_f)N_f^^m'=C' …(b) σ^^__<max>(N_f・T^^-)^n'=D' …(c) where m' and C' are material constants and S, β, n' and D' are experimental constants depending on σ_s and materials (see Tables 3 and 4). σ_B and ε_f are the ultimate stregth and the fracture ductility of each material under the static tensile test. T^^- is the duration of maximum stress under the impact fatigue test. (2) From the above results, it is also found that the relation between stress amplitude σ^^-_a and mean stress σ^^-_m for each material is approximately given in the following form: σ^^-_a=(σ^^-_0)/(1-σ^^-_a/σ_B)(1-σ^^-_m/σ_B) …(d) where σ^^-_0 is stress amplitude for the case of σ_s=0. This approximation results in an underestimation of the strength for the case of (σ^^__s>0,σ^^__m>σ_a), on the other hand, in an overestimation for the case of σ_s<O. (3) From the results of impact fatigue tests for specimens systematically varying prestrain ε_<pre>, it is found that the process of fracture is creep type but cyclic behaviour of permanent strain ε is different from that for the case ofε_<pre>=0. It is also difficult to obtain expressions (a) and (b) for the case of ε_<pre>≠0 by using the constant creep rate Δε_c and the plasticity strain rate Δε_c. (4) Therefore, the expression (c) is directly applied to the estimation of the relation between the fatigue strength σ_<max> and the fracture life N_f. The strength parameter D' in eq. (c) is also estimated by using the ultimate strength σ'_B and the reduction in area ψ' in the following form: D'=(0.80+0.0016ψ')σ'_B …(e) And n' is assumed to be the same value with that for the case of ε_<pre>=0. This estimation shows good agreement with the experimental results except the case of SS41 steel specimens having precompressive strain and in the comparatively high cycle range.
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[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
Article type: Article
Pages
197-207
Published: September 25, 1990
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Article type: Appendix
Pages
App1-
Published: September 25, 1990
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Article type: Cover
Pages
Cover2-
Published: September 25, 1990
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