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Published: September 30, 1980
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Article type: Appendix
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Published: September 30, 1980
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Article type: Appendix
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Published: September 30, 1980
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Article type: Appendix
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Published: September 30, 1980
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Article type: Appendix
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Published: September 30, 1980
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Article type: Appendix
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Published: September 30, 1980
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Michimasa ENDO, Satoshi MIURA, Katsuto FUCHIGAMI, Hisao TEZUKA
Article type: Article
Pages
1-9
Published: September 30, 1980
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The conical hatch cover has been developed as the hatch cover for the deep sea research submersible. The light-weight and high-strength pressure hull is essential requirement for the deep sea research submersible, therefore, this requirement must be met to the hatch cover as the part of the pressure hull. As the conical hatch cover, which is made of the same material as the pressure hull, has the same dynamic behavior as the pressure hull, this hatch cover has structual continuity and has a merit of a little supplement. In the course of the research development, the model tests and the FEM analyses by using mathematical models has been carried out to solve some problems concerning to the structual continuity between the hatch cover and the pressure hull and we has made remarkable achievement. This paper describes the structual continuity of the conical hatch cover based on the results about these tests and FEM analyses. It is considered that this conical hatch cover will make a great contribution together with the pressure hull to the development of deep submergence vehicle in the future.
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Michimasa ENDO, Kojiro SHIMAMOTO, Komei MORITA, Yoichi TOGUCHI, Kenji ...
Article type: Article
Pages
11-20
Published: September 30, 1980
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Observation windows for deep sea research submarine are indispensable for the manned deep sea survey, and the strength of the observation windows shoud be examined carefully to withstand pressure in the deep sea. The authors have performed some experiments to see the feasibility of observation windows for the 2000m deep sea submarine which is now under construction at their shipyard (Mitsubishi-Kobe), by adopting full-scale 90 degrees conical window made of methacrylic plastics. The results of the test and design concepts described in this report are outlined as follows; (1) Under the statical pressure test, a safety factor of six(6) has been ensured against collapse (crack observed) at maximum working pressure. Complete collapse has been observed at the pressure of 2350 kgf/cm^2. (2) Hydro-pressure repeat test of 500 times, thermal dymamic test, and creep test during life-support hours (80 hrs) have been examined and demonstrated. The results prove satisfactory in every respect and the design can therfore be applied. (3) The radial stress at the low pressure face and the axial deflection at the center of the low pressure face under the maximum working pressure were obtained and found to agree with the formulae.
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Michimasa ENDO, Hideyuki MORIHANA, Toshiki YAMASAKI, Mototsugu AKASHI, ...
Article type: Article
Pages
21-30
Published: September 30, 1980
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The exostructure of the 2000m Deep Submergence Research Vehicle is designed as a structure to install a pressure hull, batteries, electric inverters and a distributor, main ballasting tanks, buoyancy materials and so on. Also this exostructure has to endure two loading conditions as follows; one is applied when the vehicle is recovered from sea surface using an A frame crane which is mounted on a support ship, the other is applied while the vehicle is transported on board. While the weight of the vehicle is considerably related to that of the exostructure, so the exostructure must be simplified and the weight of it must be reduced. In order to satisfy these requirements, the exostructure consists of a space frame structure of titanium extrusions and FRP skin plates. This paper mainly describes the design consideration, and the fabrication process of the space frame structure for the 2000m Deep Submergence Research Vehicle.
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Shoichi OHTANI, Hirokazu HAYAKASHI
Article type: Article
Pages
31-37
Published: September 30, 1980
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It is very desirable in antenna designing to know Effective Height of Antenna as correct as possible. Especially, as for distress frequency of 500 KHZ, it is a SOLAS requirement to keep the receivable field strength of 50 μV/m at 280 km apart for main facility and at 190 km apart for auxiliary facility. These correspond to 87.6 dB for main facility and 81.4 dB for auxiliary facility at 1 km apart from ship respectively. As the radiation of transmitter must comply and meet the above requirements, the efficiency of antenna becomes important. However, recently, antenna have been arranged around ship's housing because of convenience of loading and unloarding or maintenance of antenna. Therfore, efficiency of antenna decreases extremely, as the power radiated from antenna is absorbed with ship's strutures such as Radar post, Funnel, etc. By comparing theoretical antenna effective height from actual antenna length (Vertical and horizontal length) and antenna effective height from Radio inspection datas of about 70 ships such as radiated field strength and antenna current and using statistical technic, the Authors decided practical co-efficient as for antenna effective height. In this paper, method of antenna effective height prediction and selection of coefficients are described.
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Sumitoshi MIZOGUCHI
Article type: Article
Pages
39-44
Published: September 30, 1980
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A data processing system for seakeeping tests has been provided in IHI Seakeeping and Maneuvering Tank. The test data are analysed by on-line in real time, and the results are printed out on a printer and plotted on a drum type plotter immediately after the tests The followings are contained in the analysing programs developed for the present system. (1) amplitude and phase analysis for tests in regular waves (2) determing the coefficients of derivatives in equations of motions by vertical and lateral forced oscillation test (3) determing the roll damping coefficients by free rolling test (4) spectrum analysis in irregular waves A method using the leakage effect in Fourier transformation is developed to determine the basic frequency used for analysing reasonably the test data in regular wave which contains irregular high frequency noises. This report introduces the softwares and hardwares assembling the above system.
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Hiroyuki SADAKANE, Toshio HISHIDA
Article type: Article
Pages
45-51
Published: September 30, 1980
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From the change of speed of the wind current along a wave surface, it is expected that the inclining moment due to wind pressure acting on a ship increases on a wave crest and decreases on a wave trough. But the wind moment on a ship, especially on a small vessel, may be influenced not by the wind speed but by other factors. Two dimensional wind tunnel tests, for example, prove that wind pressure distributions on the surface of a box-shaped model on a wavy surface, and the characteristics of the wind moment and the drag on the model, unexpectedly change with the location of the ship-model relative to a wave trough. In this paper, these factors are discussed based on the experimental results.
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Ryuji SAKATA, Yoshio YAMAGAMI, Tetsuro IKEBUCHI
Article type: Article
Pages
53-59
Published: September 30, 1980
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In regard to a box type floating vessel as one of the fundamental configurations of a floating ocean structure, this study has been proceeded with to establish an estimating method of its motion in waves with high accuracy. The authours have carried out forced oscillation tests and wave exciting force tests in beam seas by use of a box type vessel of low length-to-beam ratio (L/B=1) which is supposed to have three-dimensional effects, and made two-dimensional and three-dimensional theoretical calculations, and then compared the test results with the calculation results, with the following conclusion brought about. 1) The added mass for heave and amplitude of wave excited heaving force agree well with those obtained by a three-dimensional calculation, but not by a two-dimensional calculation. Three-dimensional effects especially appear in the added mass for heave and the amplitude of wave excited heaving force, and this tendency is more remarkable in shallow water. Therefore, a three-dimensional calculation is very useful. 2) The damping force for sway, added moment of inertia for roll, coupling inertia of roll into sway, and amplitude and phase lag of wave excited swaying force are in agreement with those obtained by a two-dimensional calculation, as well as a three-dimensional calculation. 3) In heave and roll, the damping terms obtained from tests cannot be fully explained only by the wave damping, without viscous damping. The estimation methods of them backed up by experiment are necessary. 4) Shallow water effects appear in the heave, roll, heaving force, rolling moment, and the sway and swaying force in a range small in ξ_b (=ω^2B/(2g)), that is, in a range of long wave length.
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Hiroshi MINEMATSU, Nobuhiro NOJIRI, Shigeo MITA
Article type: Article
Pages
61-68
Published: September 30, 1980
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Recently, jumbo marine structures such as floating airports, offshore cities, etc., supported by a large number of identical floating elements, have aroused general interest. In these structures, interaction effects between floating elements have great influence upon wave forces and drift forces both on the whole structure and on each of the elements, and upon wave heights between elements as well as those before and behind the structures. It is, therefore, not sufficient to apply methods for a single floating body and simple superposition techniques to the prediction of wave forces, etc. on these compound structures ; it is necessary to develop a method which properly takes into account the interaction effects. On this subject, there is a basic study by Ohkusu, followed by Masumoto's and Takai's studies. We believe, however, that the experiments and calculations of these studies are not systematic enough to reveal the essential characteristics of the interaction effects. In order to make clear the phenomenon more thoroughly, we carried out extensive experiments and investigated the influences of a number of parameters on the interaction effects, and then compared the results with theoretical calculations. From the study, it is found that the intervals of columns, P, that is, the spacing of cylinders in the direction of wave propagation, decides the patterns of interaction effects to the wave length, where as the intervals of rows, B, and the number of columns, N, have influence principally on the intensity of interaction effects, and that there is a fairly wide frequency range abut P/λ=0.5 where incident waves are almost perfectly reflected.
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Takeshi FUWA, Jun ISHIZAKA
Article type: Article
Pages
69-79
Published: September 30, 1980
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Free water surface effects on the hydrodynamic characteristics of a 2-dimensional foil section running with zero attack angle are examined through model experiment and numerical calculation. The foil section is used as an anti-pitching foil of a catamaran ship, which has shown remarkable results in the tank test. The catamaran ship equiped with the anti-pitching foil between its twin hulls, which is obviously effective as a transverse strength member, has fairly good propulsive performance as well as good seaworthiness in rough seas. The model experiment of the foil is performed in a few conditions of submergence and advance speed corresponding to the working range of the anti-pitching foil. Surface pressure distribution is measured by means of the SCANI valve & differential pressure gauge system, and the hydrodynamic forces and moment by a load cell. It is known by the measurement that free water surface effects on the lower surface of the foil is very small and that there is little change in the pressure distribution on it by the change of running conditions. Pressure distribution on the upper surface varies according to the change of submergence and advance speed. In the region where Fn > 1.0, pressure distribution and observed flow field over the foil are smooth. The lift coefficient varies smoothly and the drag coefficient gives almost constant value in the high speed region. In the low speed region, pressure distribution, flow field and hydrodynamic forces show drastic changes to small changes of the running conditions. When the submergence is very small, an adverse pressure gradient or a negative lift coefficient is seen in the low speed region. Free water surface effect on the pressure distribution is negligiblly small for the condition f/c > 1.0 and Fn > 1.0. The effect to the lift coefficient, however, is still seen even when f/c= 2.0. Numerical calculation of the linearized problem by means of the surface vorticity distribution method is performed. Wholly speaking, the comparision of the surface pressure distribution between measurement and calculation shows good agreement throughout the range of present measurement. Some discrepancies are seen in the case where the submergence is small and Fn <1.0. The separation of flow on the upper surface near the trailing edge is also observed when Fn < 1.0 for deeply submerged condition.
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Shigeru ASAI
Article type: Article
Pages
81-91
Published: September 30, 1980
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There have been ever increasing demands for estimation and evaluation of manoeuvrability of ships in early stage of ship form design. For this purpose, investigations were made on a practical method by use of PMM tests and theoretical background. In PMM test results, the dependence is recognized of manoeuvring derivatives on the velocity amplitude ; and therefore much inconvenience has been experienced in the application of those derivatives for manoeuvring predictions. To overcome such inconvenience, a practical method is presented, in which analysis is made for damping force components derived from total hydrodynamic reactions by subtraction of inertia forces. By use of the PMM test results obtained through the method, and with the help of theoretical approach, rudder area- and scale-effects are investigated. On the scale-effect especially, the use of wake correlation factor is examined and utility of the method is shown.
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Kazuhiro HASEGAWA
Article type: Article
Pages
93-103
Published: September 30, 1980
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A performance criterion of autopilot navigation is a long-discussed topic but remains still fresh. It is necessary to carry out model experiments to evaluate the criterion and obtain the weighting factors of the criterion. But because accuratc measurement of longitudinal hydrodynamic force was difficult, most researches ended in qualitative approach. In the present paper, we derive the performance criterion from the concept of energy increase due to yawing. The criterion is found to consist of two parts ; elongation of sailing distance and thrust increase due to steering and yawing motions. The former is proportional to rms value of course deviation and the latter, depending upon ship dynamics, is given by rms values of rudder angle and rate of turn. Each weighting factor to rms values is obtained by model experiments. Some comments on the estimation and the scaling-up methods of derivatives are given.
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Hiroshi ISSHIKI
Article type: Article
Pages
105-111
Published: September 30, 1980
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Expressions of a fundamental singularity advancing at the constant speed in a rectangular canal is obtained by superposing free waves in the canal. This solution satisfies the boundary conditions exactly. The steady part of a pulsating fundamental singularity is also derived. Energy trapping phenomena in the canal is briefly discussed.
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Shozo OKAZAKI, Kiyoshi HASEGAWA
Article type: Article
Pages
113-120
Published: September 30, 1980
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Recently, from the points of security and economization, the use of carburized gears for the marine reduction gear is on the increase instead of through-hardening gears widely in use. On the fatigue strength of carburized gear, there seems to be much influence of retained austenite besides effective case depth and core hardness. Therefore, in designing the marine carburized gear, it is important to know the allowable amounts of retained austenite. This report presents a study of the effect of retained austenite on the fatigue strength of carburized SCM22 steel. The results of our experiments indicate that more than 20% retained austenite lower the fatigue limit considerably. But these results differ greatly from the values of fatigue limit calculated from both the hardness distributions of specimens and the residual stress intensities obtained from the amounts of retained austenite. This difference is considered to be caused by the development of surface and grain-boundary carbides.
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Masatoshi BESSHO, Hiroshi KAWABE
Article type: Article
Pages
121-126
Published: September 30, 1980
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Following the former report, we develope the boundary element method, named so by Brebbia, for the stress concentration by uniform bending of a hole in an infinite plate. To verify its usefullness and accuracy we show some numerical examples of stress concentration both bending and tension cases. Then, making use of the introduced formula to give variation of stress and strain energy when the shape of a hole varies very slightly, we try to smooth or reduce the stress concentration around a part of given hole.
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Kouhei MATSUMOTO, Kenji ARIMA
Article type: Article
Pages
127-134
Published: September 30, 1980
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This paper deals with the coupled effect between a fore-and-aft vibration of superstructure and a vertical vibration of ship's hull. Characteristics of the coupled vibration were discussed by using the simple model, namely, one beam and mass-spring model. Main conclusion are as follows : 1) Coupled effect depends on four parameters. One is position of superstructure. Second is a ratio of distance between fore and aft wall of superstructure to ship's hull length. Third is a mass ratio of superstructure to ship's hull. The last is an uncoupled natural frequency ratio. 2) Natural frequencies of the coupled vibration obey the law of so-called "spring-off". But the law of "spring-off" for vertical vibration is rather complicated compared with that for longitudinal vibration. 3) When uncoupled natural frequencies coincide with each oter, coupled ones spring off in the largest amount.
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[in Japanese], [in Japanese]
Article type: Article
Pages
135-141
Published: September 30, 1980
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Article type: Appendix
Pages
143-144
Published: September 30, 1980
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Article type: Appendix
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App6-
Published: September 30, 1980
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Article type: Cover
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Article type: Cover
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Published: September 30, 1980
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