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Article type: Cover
Pages
Cover1-
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Article type: Cover
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Cover2-
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Article type: Appendix
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App1-
Published: September 30, 1978
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Jiro OKAMOTO, Ryoichiro SASANO, Masahiko NAMURA, Tsutomu INOUE, Mutsuh ...
Article type: Article
Pages
1-10
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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In view of recent economical environment a new concept for improving productivity of ship construction is needed in this industry. It should be applicable not only in expanding production but also in a situation requiring decrease of production. The new concept should not depend on investment in equipments, but stress on improvement of procedure and production control. It is considered that tact system of block assembly and construction on berth is quite efficient and separating hull construction work and outfitting work would result in improving productivity, safety and surroundings of each work. In our shipyard this production procedure is applied in building series of cargo ships, based on the tact system, separating hull construction and outfitting work. It is called "hull-outfitting separating procedure". In this paper the concept, and practical procedure and method of small sized ships construction are discussed in detail.
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Kensaku NOMOTO, Hisayoshi TATANO, Takashi KANEDA
Article type: Article
Pages
11-18
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Sailing is very old yet a highly gallant way of ship propulsion. This paper represents a scientific analysis on it. The procedure is: to predict hydrodynamic force and moment acting upon a ship's hull from model tank test, taking account of leeway, heel and counter rudder deflection; to predict aerodynamic force acting upon sails from model sail experiment; then putting these data into the equation of equilibrium, we obtain ship speed, angle of leeway, angle of heel and rudder deflection for a given wind velocity and direction. Trial study on a 7.8 metre cruising sloop proved to be a satisfactory result on the whole. Such study will hopefully provide a useful help to yacht designers by, e.g., telling him an optimum amount of "lead" (distance between C.E. and C.L.R.) of a given design.
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Satoru MATSUKI, Keiichi KARASUNO, Muneyuki OKUMURA, Toshihide KITAMURA
Article type: Article
Pages
19-33
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Training ship FUKAE-MARU 360 GT equipped on board a ship a maneuverability transducer, which is a device changing her own maneuverability to other ship's one apparently. In order to change her own maneuverability of yaw (ahead) motions, a mini-computer is linked between the steering wheel (CPP control lever) and the steering gear (CPP driver). The computer controles rudder angle (CPP blades angle) to realize an optional maneuvering motion characterized by a different maneuverability from the original one. Accordingly a ship operator on board is possessed with the illusion that he handles another ship. As the transducer on board is able to immitate other ship's maneuvering motions, the training ship may be called a onboard ship handling simulator. The mock ship ranges from the original training ship to any large ship; using Nomoto's steering quality indices K-T, turning ability index K is 0.05∼0.2 (1/sec) and course stability index T is 10∼150 (sec), where the original indices of the training ship are K≒0.2 (1/sec) and T≒13 (sec) at ship speed 10 knots. This device must be useful for 1) ship handling training for students 2) studies of man-machine system on ship handling 3) studies of correlation in man-machine system between full-scale ship and ship handling simulator
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Shoji UNE, Kensaku NOMOTO
Article type: Article
Pages
35-45
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Labor cost is now the greatest burden to the shipping industry in this country. Rapidly growing fleet of carriers flying "flags of convenience" tells us that strain. Only solution is to minimize the crew size by introducing new systems of ship operation. In this paper we firstly examined the existing system in view of man-machine hybrid control. Queueing Theory is employed for the purpose. We assume two categories of new systems of ship operation for further consideration, i.e., "less-manned" ship and "unmanned" ship. Less-manned ship does not essentially differ from the contemporary one but with a crew size as small as practicable. Unmanned ship makes ocean passage with none, or at most, a few specially-trained operators, but is to be served with shore-based crew while manoeuvring in and out of harbours. This idea comes from our analysis which tells that functions of crew in coastal waters and harbours are substantially different from the one in open sea. Automatization of ocean passages, both navigation and running machinery, will be practicable and reliable at a reasonable expense. Coastal navigation and manoeuvring in and out of harbours will, however, depend much on manual handling and human decision-making at least for the time being.
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Takamune KITAZAWA, Hidenobu TANAKA
Article type: Article
Pages
47-57
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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The Wave resistance of cargo ships of a high block coefficient is calculated by the low speed theory in low and medium speed range. The nonlinearity of the free surface condition is ascertained to exert great influence upon the wave resistance, and the results calculated by the low speed theory coincide fairly well with the measured results, although the waves generated by the afterbodies are entirely neglected. The wave resistance of full ships, however, can not always be predicted with good accuracy by the low speed theory. Therefore, the boundary value problem is scrutinized by making use of Green's function, and some comments on the improvement of the low speed theory are mentioned.
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Matao TAKAGI, Ryusuke HOSODA, Yasushi HIGO
Article type: Article
Pages
59-64
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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It is shown that Gerritsma's formula of the resistance increase can be derived by energy consideration. The co-ordinate systems and control surface which are used in this investigation are shown in Fig. 1 and Fig. 2, and it is assumed that the disturbed velocity potentials are derived by strip theory. The deduction begins with head sea condition and then reaches oblique sea conditions.
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Toshio SUZUKI, Hajime TSUKAMOTO
Article type: Article
Pages
65-72
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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The behavior of the bilge vortices in the stern flow field of full ship forms is characterized by the interaction between the vortices and the hull surface, which yields the distorsion of wake distribution, too. This paper presents a study of the interaction between the boundary layer of the flat plate surface set in parallel to uniform flow and a longitudinal vortex generated by a wing tip inserted in the boundary layer. Numerical calculations are carried out and compared with experiments. It is shown that the inverse vortices are generated on the plate surface and are diffused and convected from the surface. The longitudinal vortex is forced out from the surface by the induced flow field of the inverse vortices. Scale effect of the flow field is also considered. It becomes clear that there seems to be a large scale effect about the position of the longitudinal vortex center, not only in y-coordinate but also in z-coordinate. Owing to this, the contraction rate of velocity distribution of main flow from model to ship is slightly smaller than the ratio of their frictional resistance coefficients.
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Kimio YOKOTA, Yutaka YAMAUCHI
Article type: Article
Pages
73-81
Published: September 30, 1978
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Experiments were carried out to investigate fatigue strength of plate subjected to uniformally distributed lateral load. Box type models consisting of 7 mm thickness high strength steel plate were introduced and pressurized internally. To investigate fatigue strength of the plate under elastic-plastic large deflection behavior, level of applied load was so high that maximum bending stresses of the plates were about 1.5 and 2.0 times of yield stress according to elastic small deflection theory. There were two kinds of model shape, one was a model with square plate (750×750mm; type A) and another with rectangular plate (750×l500mm; type B). Most of type A models were different from each other in some points expected to affect fatigue strength; such as sidewall thickness, welding operation, initial deflection and corrosion by saltwater. About type B models, two models were introduced, stiffener was fitted to the center of the plate for one model and not for another. Conclusions obtained from these experiments were as follows. (1) Even after 10,000 cycles of loading, no crack initiated when the maximum bending stress of the plate was about 1.5 times of the yield stress. (2) When the maximum bending stress was about 2.0 times of the yield stress, crack initiated at 1,900 cycles and failed at 5,500 cycles. (3) Effects of saltwater corrosion and initial deflection on the fatigue strength were considerable. (4) After initiated at the toe of the stiffener, crack also propagated quickly to the opposite surface.
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Hiroshi NAKAMURA, Toshiyasu TSUNENARI, Shozo OKAZAKI, Takeshi HORIKAWA ...
Article type: Article
Pages
83-91
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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A method is proposed to predict the fatigue life under survice coditions subjected to temperature, corrosion and stress variations simultaneously using the results which were obtained from tests under stress variation, stress and temperature variations, or stress and corrosion variations. In this method the fatigue life L is calculated by following equation; L=L_0/Σ (1/ηTij・1/ηPHi・D_<ij>) where ηPHi and ηTij are the coefficients in relation to the variations of corrosion and temperature respectively and D_<ij> is the fatigue cumulative damage. The value of ηPHi range between 0.16 and 0.64 for 13%Cr-Mo steel tested under stress and corrosion variations. The value of ηTij range between 0.20 and 116 for Cr-Mo cast steel tested under stress and temperature variations.
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Junkichi YAGI, Yasumitsu TOMITA, Hideaki TATAMI
Article type: Article
Pages
93-103
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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Reversed plane bending fatigue tests were carried out in intermediate and high cycle ranges using Schenk type testing machines. Types of specimens were plane, butt welded joint and cruciform fillet welded joint and their material was mild steel (SM 41 B) of 6 mm thickness. For each type of specimens, 35 to 50 pieces were tested at the same stress level and three different of stress amplitudes were imposed. Test results were examined by a statistical analysis. The main conclusions obtained are as follows: 1. Statistical distribution of fatigue life for plane specimen, butt welded joint and fillet welded joint fitted fairly well in logarithmic normal and Weibull distribution rather than normal distribution. 2. The scatter range of fatigue life of welded joints had little correlation with the shape of reinforcement and was the same order as that of plane specimen. 3. The ratio of crack initiation life to fracture life for welded joints was nearly equal to 0.7. 4. Statistical distribution of flank angle θ and toe radius ρ of welded joints was represented by logarithmic normal distribution, and that of bead height h and bead length l of joints was represented by normal distribution.
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Toshiyasu TSUNENARI, Shigeki KOE, Hiroshi MORITA
Article type: Article
Pages
105-113
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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In order to obtain the effect of specimen width on the fatigue strength of welded joint, repeated tensile loading fatigue tests were carried out on the two kinds of notched specimens having three different specimen width, and strain behaviours at notch root, initiation of fatigue cracks and behaviours of crack propagation were observed. Then the same tests and observations were performed for the non-load carrying fillet welded specimen. And the followings are concluded by comparing the crack initiated position with the distribution of strain range, the strain restraint and those variation with load cycling. 1) On the crack initiation and failure lives of the notched specimen, the effect of specimen width was negligible small. 2) The crack initiation and failure lives of welded specimen are affected by specimen width, and the fatigue strength reduction factor (η) to the fatigue strength of the specimen with B/t=1 is obtained as follows B/t<__-8 for failure life (N_f) η=1-1/7(1-1.762N_j^<-0.0589>)(B/t-1) for crack initiation life (N_c) η=1-1/7(1-3.462N_c^<-0.1174>)(B/t-1) where B is specimen width and t is plate thickness.
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Junkichi YAGI, Toshihiko FUNAKI, Yoichi HATTORI, Michio OTA
Article type: Article
Pages
115-123
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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In the first report, to reveal the feature of racking phenomenon a structual analysis of a simple box girder under unsymmetric load was carried out. In this paper, an advanced analytical method for racking deformation of hull girder which has many transverse rings and some bulkheads was derived. And some tortional tests of box girder with transverse rings and bulkheads were carried out, and test results were compared with the theoretical values. From these results, the following conclusions were obtained. 1) The racking deformation of hull could be analysed by the theory and fairly good agreement between experimental and theoretical values was found. 2) On the prevention of racking deformation of hull girder, transverse bulkhead has large effect, but transverse rings have little one.
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Junkichi YAGI, Toshihiko FUNAKI, Yoichi HATTORI, Michio OTA, Masakazu ...
Article type: Article
Pages
125-131
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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In the previous paper, a study on the racking deformation of hull girder with many transverse rings or bulkheads was made using analytical solutions. In this paper, an advanced analytical method was derived for racking behaviour of hull girder with two decks and hull girder model was tested under tortional load. The test results were analysed by the above method and following conclution were obtained. 1) The test results show excellent support for the analysis of racking deformations of hull girder with many transverse rings, two decks and a bulkhead. 2) On the prevention of the racking deformation, effect of two decks and trnasverse rings are small respectively, but the effect of two decks is increased by interaction of the decks and rings.
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Yoshikazu MATSUURA, Kenji ARIMA
Article type: Article
Pages
133-138
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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This paper deals with an investigation into the accuracy of the calculated added virtual mass for a circular cylinder in vertical bending vibration, floating at a free surface, half-immersed in deep water. Calculations of the added virtual mass of the circular cylinder are carried out by three methods, that is, Taylor's, Kumai's and the present authors' ones. Vibration tests of circular cylinder corresponding to each end condition of the above three methods are also made for experimental verification. It is concluded that Kumai's method, which satisfies the end condition φ=0 (φ:the velocity potential of the surrounding water) at the free ends of the cylinder, is practically useful for a long cylinder. In addition, it is shown that the distribution of the added virtual mass along the length of the circular cylinder is given by a simple formula, which involves only the length, diameter and the number of nodes of the flexural modes of the cylinder.
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Hajime KAWAKAMI, Tokio OHNISHI
Article type: Article
Pages
139-148
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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It is well known that the natural frequency for flexural vibration of plate under compressive load decreases, as the load increases. According to the theoretical studies of this phenomenon in the past, the natural frequency becomes zero when the load reaches the buckling load. By the contrast, the authors' experiments have shown that the natural frequencies do not decrease so much as the theoretical values. This disagreement is considered to be because of the initial deflection. In this paper, the authors have studied the flexural vibration of rectangular plate with initial deflection under compressive load by using the energy method and appling the theory of thin shells. And in order to verify the theoretical results, a vibration experiment has been carried out. The results have been compared with the theoretical calculations and a reasonable agreement has been confirmed. The results obtained are as follows: (1) When the compressive load increases and its magnitude is small in comparison with the buckling load, the natural frequency of plate with initial deflection decreases. But when the load approaches the buckling load, the deflection of plate becomes large rapidly and so the natural frequency increases. (2) The above-mentioned phenomenon can be explained by the calculations given in this paper and a simplified formula of natural frequency based on these the oretical calculations has a good accuracy. (3) In the case of ship plating, the effects of the compressive load and initial deflection on the natural frequency are considerably large.
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[in Japanese]
Article type: Article
Pages
149-160
Published: September 30, 1978
Released on J-STAGE: March 30, 2018
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[in Japanese]
Article type: Article
Pages
161-166
Published: September 30, 1978
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Article type: Appendix
Pages
167-168
Published: September 30, 1978
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Article type: Appendix
Pages
App2-
Published: September 30, 1978
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Article type: Appendix
Pages
App3-
Published: September 30, 1978
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Article type: Appendix
Pages
App4-
Published: September 30, 1978
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Article type: Appendix
Pages
App5-
Published: September 30, 1978
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Article type: Appendix
Pages
App6-
Published: September 30, 1978
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Article type: Cover
Pages
Cover3-
Published: September 30, 1978
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Article type: Cover
Pages
Cover4-
Published: September 30, 1978
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