-
Article type: Cover
Pages
Cover1-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Cover
Pages
Cover2-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Katsuto KANAO, Motofumi MIYAKUBI, Kunihiko AKAMATSU, Katsuteru WAIDA, ...
Article type: Article
Pages
1-6
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
Ships are provided with many kinds of purchased equipments with various quality characteristics. Though the inspection method we have is adequate to get good quality of these equipments, the recent economic situation obliges us to rationalize the inspection method. From this point of view, we, department of inspection, have studied sampling inspection method for a part of purchased equipment manufactured based on our drawings. As a result, it has been proved that this method is applicable from the stand point of quality assurance.
View full abstract
-
Minoru MORI, Motoaki YANASE, Seiji TERADA, Tatsusaburo NAKAMURA
Article type: Article
Pages
7-14
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
The so-called "glycine" test was carried out in order to evaluate the performance of antifouling paints. However, unsatisfactory results were obtained. So, a modified glycine test was examined. The satisfactory copper leaching rate/time of exposure curves were obtained. In addition, Electron probe micro analyzer was used to obtain an information about the behaviour of copper leaching from antifouling paints.
View full abstract
-
Shinsuke AKAGI, Toshiaki MIYATAKE
Article type: Article
Pages
15-22
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
When fluid is pumped out from a ship's tank, flow in the tank is obfen obstructed by inner structures of tank. In order to avoid these phenomena, suitable size of drain holes are to be provided for tank structural platings. However, few studies are found concerning these kind of problems. This paper deals with these types of flows, and gives a well applicable calculation method.
View full abstract
-
Yoshiki HIRANO, Hitoshi HOTTA
Article type: Article
Pages
23-31
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
When a self elevating platform carried out the jacking up or jacking down operations in the rough sea, its very long legs collide to the sea bottom due to the pitching motion of the platform's barge hull, especially at the case of the legs are very close to the hard bottom. This shock load will affects very seriously to the leg's constructions and jacking mechanism. The shock load related with the wave height and period, also the gap between the leg base and the sea bottom. Model experiments were carried out at the Tokai University's circulating tank which has glass wall on both side. We observed the behaviour of the leg motion and took the 8 m/m movies. Also the shock load measured by the accelerometers. We get following results. The shock load on the weather side legs is larger than that on the lee side legs and maximum value is about 2.5 times of statically hull weight load on the each legs. i.e) 1/4× (hull weight), in case of gap δ= 0. S.E.P. swims down jumpingly to the lee side of wave because there are no mooring and restricted by anchoring seriously bending and shering effect to the legs. Meanwhile, these collision phenomenon occures few cases and has very short duration time in the whole working periods of S.E.P. . Then if we can use anti-pitching devise at this time, it is very efficient to decrease the shock lord. Actually it was reduced to about 60 percents in our model experiments.
View full abstract
-
Masanori SUGIURA
Article type: Article
Pages
33-42
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
Added masses, damping coefficients and wave forces on semisubmersible bodies are calculated by making use of singularity distribution method following Faltinsen and Michelsen The accuracies of the results of wave forces are examined by comparing the values of the diffraction problem with those of the radiation problem from Haskind relation. Total added masses, damping coefficients and wave forces estimated from the simple addition of those of elementary bodies are compared with those calculated as total bodies. In some range of wave number, there seem to be considerable differences between these two values.
View full abstract
-
Tadao TAKAI, Shigeru YAMAMOTO, Hiroshi ISSHIKI, Yukiharu NEKADO
Article type: Article
Pages
43-49
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
Two problems are calculated by the "Joining Method of Divided Regions". The one is the diffraction wave through two vertical flat plates. The another is the radiation wave produced by the sinsoidal pressure fluctuation acted on the free surface between two vertical flat plates. These results are compared with those by an approximate method in which the vertical motion of fluid column between the plates is replaced by the rigid body motion. The agreement of these two methods is fairly good, if the distance between the plates is the same order as the draft. The discrepancy between the calculation and experiment is remarkable in the diffraction problem in the vicinity of a wave length where the motion of the fluid column between the plates is resonant.
View full abstract
-
Hiroshi KAMOTO, Yoshio YAMAGAMI, Hirofumi ONIKI
Article type: Article
Pages
51-56
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
The paper deals with model test techniques to estimate manoeuvring qualities of actual ships. Scale effect is an important problem in estimating the manoeuvring qualities of actual ships by model tests. To solve this difficult problem, two model test techniques are proposed; one is a free-running test technique with large models (length of models ≒ 15m), and the other is a captive model test technique with small models (1ength of models ≒ 3m). In the former, by using large enough models, and in the latter, by improving the technique, such as by choosing an adequate swaying or yawing frequency, we consider the problem of scale effect can be solved. From the fact that some manoeuvring characteristics estimated by these model test techniques agree well with those obtained from manoeuvring tests for some actual ships at sea, it is concluded that these techniques would be effective to solve the scale effect problem.
View full abstract
-
Hiroyuki SADAKANE, Toshio HISHIDA
Article type: Article
Pages
57-63
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
We used to understand the wind action usually in its summarized features. But, minute experiments prove that the wind acts on horizontal surfaces of a vessel in a manner different from on vertical ones. The difference has influence on the behavior of a vessel in the wind. Sometimes, the heeling angle varies according to the area or the position of a horizontal surface even in the wind with the same speed. In some cases, the wind resists less to the rolling in the wind than in no wind, moreover, a vessel goes on rolling in the wind without any periodic excitation as waves. The present paper deals with those phenomena.
View full abstract
-
Susumu HIRANO
Article type: Article
Pages
65-71
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
It is well known that J.Gray demonstrated on the basis of engineering calculations in 1936 that it is possible for dolphins to attain their high swimming speeds only in the case of total laminar flow. Swimming locomotion under conditions of turbulent flow, would require approximately seven times the power which are estimated to be capable of producing. As is known, hydrodynamic thrust in dolphin locomotion, chiefly, is generated by periodically repeating oscillatory motions on the vertical plane of tail fin of complex shape. At the present time we possess incomplete data for shape of a tail fin. Therefore, at the present stage of investigation with the aim of finding the thrust of a tail fin, it is important to obtain shape and steady state characteristics of a tail fin. In order to investigate into the steady state characteristics of a tail fin, the three component tests has been attempted for a half sized tail fin model in towing tank, and the results is compared with the calculated values of the wing theory.
View full abstract
-
Nabil SEHSAH
Article type: Article
Pages
73-84
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
The cross flow profile in the three-dimensional turbulent boundary layer is discussed, and it is shown that it is more convenient to express the cross flow velocity as an explict function of the main flow velocity. Considering polynomials of different degrees, it is shown that the 3rd degree polynomial is better in representing the cross flow in the sence that it decreases the dependency of the calculated limiting streamline angle on the conditions at the boundary layer outer edge. The concept of the skew function, which gives the distribution of the velocity component normal to the wall shear stress is introduced, and it is shown that this function is not universal. Using the 3rd degree polynomial for the cross flow it is possible to represent the different trends of the available experimental results for the skew function. The boundary layer calculations are conducted for a tanker model using a two parameter cross flow profile and Johnston equation as the auxiliary equation for the cross flow. The results are in reasonable agreement with the experimental trend, although there are some points which still need more research.
View full abstract
-
Kenichi HATTORI
Article type: Article
Pages
85-98
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
A ship is essentially an indeterminate structure in which internal forces such as bending moments and shear forces may become very large at certain points of structure and many kind of stress concentrations may occur at points of discontinuity. In Section 2, the concept of stress concentrations due to internal forces and discontinuities are discussed with the aid of the finite element method. In Section 3, the feature of stress concentrations which may be classified into several types is presented, although various phenomena of stress concentrations are observed in actual ships. Finally, the question how to deal with such stress concentrations at ships' structural design is discussed.
View full abstract
-
Hiroshi ISHIGAKI, Matao TAKAGI, Youichi HATTORI, Norihiko SAKATA
Article type: Article
Pages
99-105
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
The calculation method of springing vibration in irregular waves has been studied. In this report, however, numerical calculation of response of three large tankers (D.W. 130,000 tons, 230,000 tons and 280,000 tons) in regular waves has been carried out in order to investigate the tendency of springing phenomena. In results following facts are clarified. l) As ships grow larger, response becomes bigger. 2) In case of D.W. 130,000 ton tanker, responses of 2nd and 3rd resonance are very small in comparison with that of primary resonance but in case of D.W. 230,000 ton and 280,000 ton tankers, responses of 2nd and 3rd resonance are not negligib1e.
View full abstract
-
Kenji ARIMA
Article type: Article
Pages
107-113
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
This paper deals with two calculation methods, using Rayleigh-Ritz method, of natural frequencies of vibrating circular cylinder submerged horizontally or vertically in water. These methods were presented previously by the author, of which one was the hydroelasticity method and the other the approximate method. The former was very effective for the analysis of flexural vibration of circular cylinder in water and the latter for the analysis of ship vibration. In this paper, natural frequencies of circular cylinder computed by the approximate method are shown to be comparatively in good agreement with those computed by the hydroelasticity method.
View full abstract
-
Hiroshi NAKAMURA, Shozo OKAZAKI, Tomonobu OKADA
Article type: Article
Pages
115-124
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
With a view to studying on the effect of varying stress on the fatigue strength of the high strength steel, the multiple repeated rotating, or plane bending fatigue tests were carried out at two stress levels on three high strength steels, which were S15CK tufftrided steel, SCM4 induction hardened steel, and l% Cr-Moquenched and tempered steel taken from the main gear for marine propulsion turbine. The results obtained are summarized as follows; (1) On the S15CK tufftrided steel, the fairly low stress under the fatigue limit is affected considerably the fatigue life, in case of σ_1=45kg/mm^2, n_l/N_l=0.03 (n_l/n_2=2×10^4/5×10^6). (2) On the SCM4 induction hardened steel, the understress till 0.5 σ_ω (σ_ω; fatigue limit) is affected the fatigue life, in case of σ_1=80kg/mm^2, n_l/N_l=0.1 (n_l/n_2=5×10^3/5×10^6). (3) On the l% Cr-Mo quenched and tempered steel, the fairly low stress under the fatigue limit is affected considerably the fatigue life, in case of σ_1=50kg/mm^2, n_l/N_l=0.1 (n_l/n_2=8×10^3/5×10^6), 0.05 (n_l/n_2=4×10^3/5×10^6).
View full abstract
-
[in Japanese], [in Japanese]
Article type: Article
Pages
125-142
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
[in Japanese]
Article type: Article
Pages
143-147
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
149-153
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App1-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App2-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App3-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App4-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App5-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App6-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App7-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Appendix
Pages
App8-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Cover
Pages
Cover3-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
-
Article type: Cover
Pages
Cover4-
Published: March 30, 1977
Released on J-STAGE: March 30, 2018
CONFERENCE PROCEEDINGS
FREE ACCESS
