Recently, the auther has developed a new lifting surface theory for low aspect ratio wings, in which the bound vortices representing the wing are distributed not over the projected surface on the stream plane but over the wing surface itself, while the free vortices are trailed along the locus of the moving wing under the category of linearized theory.
In the present paper, the application of this new lifting surface theory to screw propellers is discussed theoretically. The bound vortices representing the screw blade are distributed over the helical surface of the blade itself, while the free vortices are trailed along the helical locus of the moving blade. It is desirable to treat the problem three-dimensionally, in order to investigate the form of load distribution, not only in the radial direction but in the chord direction, in relation with the blade shapes and the working conditions. A two-dimensional integral equation that relate lift and downwash distributions on the screw blade is formulated. The numerical method of solution of the equation is obtained, considering the singularity of the kernel functions.
Besides, some numerical calculations are made to examine the characteristics of the kernel functions.

抄録全体を表示

In order to culculate the critical speed of propeller shaft, the accurate value of virtual moment of inertia of marine propeller should be estimated.
Virtual moment of inertia consists of the mass moment of inertia of propeller I and the additional moment of inertia by entrained water Δ I.
It is usual to estimate Δ I by making a percentage additon to I, varying from some 20 percent to 30 percent, but this estimate is sometimes accompanies by risk,
The auther introduced the theoreitcal formula by application of two dimensional, and three dimensional potential flow theory, and by the test results for series model propeller the coefficient of the theoretical formula were added some correction the simple practical formula for Δ I were obtained. The availability of this practical formula was also prove by the test results of torsional vibration of propulsion at sea trial,

抄録全体を表示

In this paper, the author will develops the linearized theory of partially cavitated flows about general two-dimensional lifting profiles. He proposes a partly open cavity model that the opening width is defined as a function of the cavity length. In the analysis, the expressions for quantities, such as cavitation number σ, lift and drag, will be shown as functions of the angle of incidence-α and the cavity length. Camber and thickness effects of the profile are taken into account.

抄録全体を表示

Nowadays bulbous bows of considerable dimensions have become quite common in use for low speed ships of large block coefficients, such as mammoth oil tankers and bulk carriers.
Author who has concerned himself with bulbous bow design for such ships last three years presented his conjecture over how bulbs would work to reduce the residuary resistance : in the full load condition the improvement of streamline pattern due to bulbs brings reduction uniformly for a entire speed range, while in the ballast condition the wave cancellation due to bulbs is the primary cause of a predominant reduction at the characteristic Froude number of about 0.2. The conjecture is well founded on the author's streamline observations with models as well as other experimental and theoretical evidences.
Design features and feasibility of large bulbs were discussed and some important problems were pointed out pertaining to model-ship correlation of the full ships fitted with the bulbs.

抄録全体を表示

Recently, researches on the reduction of the pitching motion of ships are actively pursued. The anti-pitching tank and anti-pitching fin etc. may be cited as examples.
This paper presents the effect of activated anti-pitching fins upon pitch reduction. The attack angle of the fins can be varried by signals of K₁ψ+K₂ψ+K₃ψ, where ψ is pitching angle and K₁, K₂ and K₃ are constant.
According to the theory which was introduced in this paper, it is desirable to take a combination, K₁ >0, K₂> 0 and K₃ < 0, in order to reduce the maximum amplitude of the frequency response. But from the viewpoint of comfort of passengers in ships, it is suitable to take a conbination, K₁ <0, K₂ >0 and K₃> 0. And it is expected from the calculation that the maximum pitch amplitude of a ship with controlled fins is about 50% lower than a ship's with fixed fins, and 60% lower than a ship's without fins.
On the other hand, an experimental study has been conducted in regular waves using pitching angle and it's angular velocity as signals to move fins. And the results of the experiments showed that more than 80% pitch reduction can be obtained, and that anti-pitching fins are also very effective for heave reduction.

抄録全体を表示

The general aspects of the data processing system, to get the response character of the ship statistically from the results of the seakeeping tests of actual ships, as well as of the model tests in irregular waves in the experimental tanks were discussed. A data processing system that is now under operation in the Ship Research Institute was introduced together with the descriptions on each elements of that system and the computing programs for the electronic computor to do the spectrum and correlogram analysis as a link of this system. An example of the application of this system to the actual ship performance test is reported, together with an attempt of the application of the results. Summary of the process to design the experiments, suitable for this kind of analysis, and some thoughts on the future development of this system were also mentioned.

抄録全体を表示

Over the past several years the Mitsui Ship-building & Engineering Co., Ltd. has been engaged in the development of a new hull form applying the theory of wave-making resistance.
This procedure is well known as “Waveless Hull Form Theory” developed by Prof. Inui.
This paper refers to the practical cases of the applications of the Theory through several experimental works.
It should seem that the results of experiments suggested a few questions how to apply the Theory. The most important ones are the followings :
(1) Applying the Theory to designs of Bulbous Bow is to be the most efficient. But the position, size and shape of “bulb” must be selected carefully through experiments.
(2) Reffering to the “Minimum Wave-Making Resistance Theory” the results of experiments have not necessarily shown a satisfactory agreements with the Theory. One reason will lie in the nonlinear effects not explained by the Theory
The authors believe the more investigations must be continued both in theory and experiment, especially in case of large tanker hulls.

抄録全体を表示

An approximate theory for predicting the GEM's cushion pressure has been derived by considering the effect of viscosity, i. e. the mixing of jet with the surrounding fluid at rest, and compared with experiments. The theory not only predicts the phenomena qualitatively, but, by suitably choosing some empirical constants, e. g. the jet-spread parameter, gives fairy good agreement with experiments.
In order to check the substantial validity of the theory, however, further minute measurements of jet motion should be continued.

抄録全体を表示

This report presents an experimental study investigating the dynamic pressure exerted on tank walls of ship by swashing internal fluid.
As the first stage to the final object, the determination of the effectiveness of the members abating swashing fluid, the case, where no obstacle such as s wash-bulkhead and deep girder existed in the tank, has been dealt with.
The model tank was 1 meter deep and 1 meter wide and the length was changed from 1. 4 meters to 3. 8 meters. Tests were carried out by putting the model tank on a specially designed rollig apparatus which is capable of simulating the pitching, surging and some other motions. The influencing factors, depth of fluid, tank length, amplitude and period of periodical motion of the tank and so on, were varied systematically. Total load, vertical variation of load and local pressure on the tank end wall was measured dynamically together with the motion of tank.
The experimental results were regularized with regard to the tank motion. From this study, empirical formulae to predict the maximum load exerted on the tank end wall were derived as shown in Eq. (13) and Eq. (15) in the case of pitching and surging motions respectively.

抄録全体を表示

Data of the transient transverse stresses during slamming obtained from sea tests showed that the transverse strength of a torpedo boat was considerably affected by the longitudinals, because the longitudinals were parts of strength members to resist the impact loads upon slamming another words, the external forces were transmitted to bottom longitudinals upon slamming immediately.
In order to calculate the reasonable transverse strength in the above case, several assumptions are introduced as follows :
1) Statical water pressure is substituted for the impact loads during slamming.
2) Statical water pressure is equally distributed over the all area of bottom shell bounded between two neighbouring transverse bulkheads along the lengthwise direction and extending transversely from the center girder to the lower chain,
3) By taking resistance of longitudinals into consideration for the transverse strength, so-called three dimensional analyses are basically applied, which were already introduced by Nishimura in the case of having deadrise.
4) A stiffened plate, which is composed of both stiffened bottom and side shells, is simply supported at two neighbouring transverse bulkheads, the edge of the side shell and clamped at the center girder.
In this paper, based upon the assumptions as above, the distribution of transverse moments and stresses are obtained by use of digital computer and compared with the results of conventional method used so far, so-called two-dimensional analyses, assuming two or three unknown forces to resist external pressure. By the above comparison the magnitudes of unknowns are determined and reversely, if these determined unknowns are applied, the two-dimensional analyses will again become an useful method to get an estimation of transverse strength at the stage of initial design. In order to get the correlation between the calculated results obtained as above and the data of sea tests during slamming, the equivalent statical pressure is first obtained from test data by making the magnitudes of calculated and experimental results equal to each other, and second the ratio of the equivalent statical pressure and the slam pressure corresponding to each boat's speed. The mean effect of variable pressures on the transverse stress, therefore, is given by the ratio determined as above, although the maximum and the distribution of pressure during slamming are always changing from time to time.

抄録全体を表示

Using the method proposed by Woinowsky-Krieger, the influence function for deflection of a wedge-shaped plate with clamped boundaries is presented in this paper. From this function, a new influence functions for “Moment nucleus” is derived and then it is converted into an influence function for a wedge-shaped two-dimensional stress field under the action of “Contraction nucleus”. Using the solution thus derived, distortion of an finite plate with a slit due to “Contract nucleus” is studied and the application to welding mechanics of a butt-welded plate is briefly indicated.

抄録全体を表示

Following the preceding paper, the author now discuss the effects due to the depth of water to the damages of cylindrical shells, because it seems to him not being well discussed yet on the quantitative measurement of water pressures due to effects of expansion of successive gas globes and damage amounts occurred by explosion in the deep sea.
The cylindrical shells used were made of high strength steel and stiffened by inner frames with different span lengths.
After hanging the cylindrical shells by wire ropes at the depth of about 30, 150 or 300 meters under the water on the about 2, 000 meters depth sea, the explosion tests were pursued by blasting TNT spherical explosives from the bottom, yielding to the small damages on shells.
This paper is mainly concerned with small local damages occurred between frames, and hence the large ones in case of buckling of frames were disregarded.
Comparing both results of experiments and calculations on water pressures and displacements, the semi-empirical formulas of time lag among peak pressures due to gas globes and the amounts of maximum concavities of damages on the cylindrical shells were determined.
The formula of maximum concavities was further compared with the experimental formula which was developed quite recently in USA in case of variable depth of water, showing good coincidences between both results up to the so-called safe depth of water.
The formula of maximum concavities which is available to the mild steel material was also determined and compared with the experimental results of the cylindrical models carried out by changing the depth of water, showing reasonable coincidences between both calculated and experimental results.

抄録全体を表示

Welded and notched wide plate specimens of high tensile structural steel were tested in constant load tests and constant net section stress tests, and welded and notched wide plate specimens and notched wide plate specimens of mild steel were also tested in constant load tests.
In each test series three kinds of initial notch lengths were provided in order to determine the effect of material properties at notch root ; mother metal, heat affected zone and deposited metal.
As a result of the tests it was found that the material properties at notch root and residual stress influence very little the initiation and propagation behavior of the low cycle fatigue crack, if weldment matches mother metal well, and that fatigue crack propagation rate changes in accordance with the change of the mode of fatigue crack.

抄録全体を表示

This paper deals with the results of the fatigue test on hourglass type and round notched specimens of 80 kg/mm² high strength steel. Strain controlled low cycle fatigue tests were carried out to investigate the notch effect on the fatigue strength reduction factor and the life ratio in the low cycle range. Two kinds of hourglass type and four kinds of round notched ones were tested. The theoretical stress concentration factor were varied in five conditions.
The following conclusions were obtained :
(1) The natural fracture strain in static tension, ε_f, is decreased as the theoretical stress concentration factor, K_t, increased. The degree of decrease of ε_f is large in the range of 1 to 1. 6 of K_t.
(2) The relation between total true strain amplitude and number of cycles to the initiation of visible crack on the surface of specimen, N_c, was obtained as ε_ta=C_eN_c^-k_e=C_pN_p^-k_p.
(3) The values of C and k can be determined in the K_t-ε_ta and K_t-C curves in the range of 1 to 4 of K_t value. For the condition that K_t is equal to 1. 00 the ε_ta-N_c relation was obtained as ε_ta=0. 36 N_c^-0.50+0. 0054 N_c^-0.087.
(4) The relation between propagation life and failure life is represented as, N_f-N_c=0. 607 N_f^0.89.
(5) The fatigue strength reduction factor, K_{f, ε}, was defined as the ratio of total true strain amplitude of smooth specimen (K=1.00) to that of notched specimen. K_{f, ε} is always higher than K in the low cycle range.
(6) The life ratio was defined as the ratio of failure life of smooth specimen (K=1. 00) to that of notched specimen. Life ratio increase logarithmicly with increasing of K_t value.

抄録全体を表示

In the preceding papers, the author and his colloborators reported the following resnlts, obtained by tensile tests of transversely-welded wide plates without any artificial notch, that brittle fracture in welded structures using some high strength steels under some conditions initiated at the fusion line of the weld-joint, and that strain concentration at the fusion line induced by welding distortion was one of the most important factors to fracture.
In this paper, the author studied theoretically and experimentally the strain concentrations at weld-joints with verious types of initial distortions in flat plates and in cylindrical and spherical shells.
The theoretical formulas presented in this paper, together with the testing method proposed in the preceding paper, would be applicable to various welded structures to prevent brittle fracture initiation which is characteristic to welded structures.

抄録全体を表示

Critical frequencies of the vertical vibration were calculated for 2 tankers, 4 high speed cargo liners and an ore-carrier, by means of the digital computation method described in the previous report (1).
The results were compared with the frequencies measured in the sea trials. Although there are some discrepancies between the computed and measured frequencies, the estimation of the frequencies of tankers and bulk carriers can be made with good accuracy by means of the empirical coefficient defined in this report.
Further the authors investigated the effects of the added virtual mass, effective breadth of the plating and the rotational inertia, the results of which showed that the rotational inertia can be neglected up to 67 nodal model. For the ships having no longitudinal bulkheads such as bulk carriers and cargo ships, the effective breadth factor seems to affect the frequencies to some degree, but the detailed study on this subject will be investigated in a subsequent report. For the practical computation, Landweber's two-parametre family with Lewis' correction is fairly applicable to the estimation of virtual added mass.

抄録全体を表示

The large ship recently built in Japan are generally of the type with the entire superstructure aft, and for these vessels special attention should be paid to vibration, especially to the fore-and-aft vibration of superstructures.
The authors have carried out some experimental and theoretical investigation on these phenomena, and the following results have been obtained.
(1) In full scale measurements, there were several peak groups recognized in the vicinities of 400600c/m and 8001, 000 c/m. of these, the lowest have possibility of resonating with the so-called blade frequencies.
(2) Measured mode curves had shown interesting characteristics.
(3) Some qualitative investigations have been made on these experimental data, and it becomes clear that the coupled motion of the main hull, the elastic support at the base deck of superstructure and the dogger have a great deal of influence upon the vibratory characteristics of superstructure.
(4) A method of predicting the lowest natural frequency of superstructure by the use of electronic computer has been obtained.

抄録全体を表示

This paper deals with the reflection and passing through of the stationary flexural wave when it propagates along the infinitely long beam with a local appendage on it.
In Part 1, the case of the concentrated impedance was described and some examples of absorbing the total propagating energy by the concentrated impedance was represented.
Ih Part 2, the case of the distributed impedance, namely that of general damping materials was dealt with. When the beam has the distributed impedance in some region the passing through of the flexural wave could be made less by increasing the impedance, but reflection of the wave also increase in this case.
The possibility of increasing the impedadce was found when the thickness directional resonance of the damping materials could be used.

抄録全体を表示

The authors previously presented a paper on the influence of the residual stresses on the buckling loads of the compressed mild steel plates in the elastic, elastic-plastic and plastic ranges. In these days, there is a tendency to use widely the high tensile steels to the ship structures, and it becomes important to clarify the effective method to use them. In this paper, it is treated the buckling strength of hibrid plates which are constituted by mild steel and high tensile steel, and the influence of residual stresses on it. The foundamental assumptions of theoretical analysis in this paper are identical with those in the previous paper. Experiments were carried out in the following for main series of specimens (supported along all edges and the dimenssons of 1200 × 580 ×814 mm), i. e. C-series (the center plate of three equi-width plate-elements is high tensile steel and the end plates are mild steel), CA-seriei (the residual stresses are excluded by annealing C-series), E-series (the center plate is mild steel and the end plates is high tensile steel), and EA-series (the residual stresses are annealed). In addition the effectiveness of the high tensile steel plates when used as compression member was studied. Conclusively it may, theoretically and experimentally, be said that the residual stress pattern in tsis paper makes the buckling loads increase slightly in the elastic range and E-series, add has small influence on C-series, generally the influence is smaller than in previous paper, and that εδ² method is effective, and that as for the effectiveness of high tensile steel, it is economical to use the mild steel, H. T. 50 and H. T. 60 according to the given external load and the width of plate.

抄録全体を表示

A study on the plastic design method of plate girders whose webs buckled in shear is presented. Local buckling of flanges and shear buckling of webs set limitations to the plastic design of plate girders, and it is recommended that the dimensions of cross section shoule be so designed as to prevent various types of buckling from taking place up to the strain hardening range.
The web hight, however, is regarded as the most important factor when we aim at the minimum weight, and girders are able to carry shear force by tension field action after buckling occurs in their webs.
So it is necessary to introduce the concept of incomplete tension field into the plastic design method. The problem was studied by K. Basler, but the interaction curve he proposed seemed to be unsafe and the theoretical direction of tension field does not coincide with our experiments.
The authors tried a different approach based on the lower bound theory and the assumption that the compressive principal stress after web's shear buckling maintains the value at buckling in the same direction. Conclusions are as follows.
(1) There are two types of shear collapsing modes. One is that the web yields uniformly along the tension field and deforms in rhomic. The other is that the yielded band grows nearly in diagonal direction and the adjacent flanges are pulled into the web finally.
(2) Interaction curve between bending moment and shearing force including the web buckling in shear is introduced. It is showed that the maximum carring moment is reduced by not only the shearing stress in web, but also the compressive stress in flanges caused by the tension field action.
(3) The generalized method to decide the collapsing load of indeterminate girders using the linear programming method is showed.
(4) Tests were carried out on 2 span continuous girders subjected to concentrated loads, and the tests results showed a good agreement with the theory.

抄録全体を表示

In this paper the results of the destructive experiment of a 1/5 scale ship hull model is reported. The model was designed to be as similar as possible to the midship part of the destroyer escort and subjected to pure bending moment.
The general buckling strength of the upper deck was mainly studied considering the effects of under-deck structures.
A loading device was specially constructed for this experiment.
Buckling of the upper deck occured over two frame spaces and its load agreed with a theoretical estimation.

抄録全体を表示

A new approach to minimum weight design of multi-story plane portal frames is proposed by basing on “Mechanism Method”.
The principle of this method is indicated as follows ;
(A) FORMULATION OF ALL THE POSSIBLE COLLAPSE MODES OF A GIVEN FRAME
All the possible collapse modes and the corresponding evaluation of virtual work of a given frame can be automatically formulated through simple combination of basic data for mechanisms of two elementary structural aggregates. Therefore the ultimate load can be easily determined by computing the smallest limit load under given Mp values.
(B) SCREENING OF THE RESTRAINING INEQUALITIES OBTAINED IN (A)
The number of restraining inequalities obtained in (A) which may increase so fast with the structural complexity can be effectively reduced by computing the limit load of each mechanism. for appropriately assumed Mp values and selecting a number of important inequalities which may be operative in the final solution of minimum weight design through comparison and arrangement of these collapse loads in the order.
(C) DETERMINATION OF LOWER BOUND SOLUTION BY LINEAR PROGRAMMING UNDER THE RESTRICTED NUMBER OF INEQUALITIES OBTAINED IN (B)
A lower bound solution of a given problem can be determined by the well established “Dual Simplex Method” in Linear Programming under the restricted number of inequalities obtained in (B).
These three steps of calculation can be combined, connected and looped into as unified process of automatic computation of which modern electronic digital computers are capable.
It is emphasied scale of the problems to be solved will not be practically influenced by the size of a digital computer to be used.

抄録全体を表示

The Ship Research Institute is conducting a long-range research project to evaluate present methods of ship structual design and to suggest improvement based on a more realistic knowledge of the loads, stresses, and motions which ships experience in service.
Measurement of ship motions, deck longitudinal stresses, web frame stresses and the wave load due to green sea were obtained as one of the series tests in above project on general cargo boat in her service in the North Pacific Ocean during the winter of 1964 and 1965.
This report outlines the scope of the tests and presents the data in some detail in order to expedite their use by other investigators.
During the entire tests, the maximum magnitudes were estimated 6.5 kg/mm² in tension and 3.8kg/mm² in compression in deck longitudinal stress, between 6.0 kg/mm² and 7.0kg/mm² in transverse web frame and between 2.0 and 4.0 m head in deck wave pressure.

抄録全体を表示

This paper deals with results of tests made on following matters.
(1) Discharge from the grille fitted on an air duct.
(2) Discharge from the punkah louver fitted on an air duct.
As the results of experiments, the empirical formulae for the coefficient of resistance in the streams at the grille and the punkah louver have been obtained.
(1) Coefficient of resistance and pressure loss at the grille.
(a) In case the grille directly fitted on the duct.
ζ'=1.36+0.86/ (SM) ² P=0.86H_m+1.36H_G
(b) In case the grill fitted on the duct by means of distance piece.
ζ'=1.49+0.92/ (SM) ² P=0.92H_m+1.49H_G
(2) Coefficient of resistance and pressure loss at the punkah louver.
(a) In case the tail of punkah louver projects into the duct.
ζ'=1.27+1.11/ (SM) ² P=1.11H_m+1.27H_D
(b) In other case
ζ'=1.55+1.27/ (SM) ² P=1.27H_m+1.55H_D
Where
ζ'=coefficient of resistance
SM=flow speed ratio
P=pressure loss, mmWG
H_m=velocity head in the main duct, mmWG
H_G=discharging velocity head of the grille, mmWG
H_D=discharging velocity head of the punkah louver, mmWG

抄録全体を表示

Recently oil tankers have rapidly become larger, and gravity flow system without cargo oil pipings has been applied to the tankers. However unfortunately we did not learn how to design the most suitable valve for gravity flow system and how to decide the bore of the valve. The auther got necessary data to decide the bore of bulkhead valve by means of simulation computation owing to electric computor.

抄録全体を表示

Recommendations about the machinery noise measurements have been lately proposed and discussed in ISO.
In this paper are discussed the several problems about the ship noise measurements according to those proposals, and this paper is based upon the results of extensive noise and vibration surveys that, over the last several years, have been made in various types of merchant-and war-ships on their trial navigations.
The results of the observations may be summarized as follows.
(1) Acceleration type vibration pickup, about 10 grams in weights, is good for solidborne noise measurements, as the load effect of the pickup and the effect of the contact surface compliance between the vibrating surface and the pickup, mounted by means of scotch tape with adhesives on both sides, are nearly negligible.
It will be desirable to adopt the acceleration levels refered to π×10^-5 cm/sec² and, if neccesary, to convert them to the velocity levels refered to 5×10^-6cm/sec.
(2) Noise level should be measured by the A weightings of sound level meters regardless of noise levels.
Noise (airborne, solidborne) analysis usualy should be made by octave band filters depend on IEC recommendation and the convertion between old and new octave band level will be made by interpolation.
Noise levels in the ship compartments and acceleration levels on the surrounding walls seem to be dispersed within several decibels.

抄録全体を表示

To ensure safe launchig of super large vessels onto limited waters, it is a matter of great importance to estimate the launching motion of ship and the position of stop.
Although there are several ways to estimate the ship motion by means of numenical method, they all lack in accuracy because of the existence of uncertain elements which can not be analyzed exactly.
On the other hand, there is a certain way to estimate the motion by means of model ship test, but it has hardly been taken notice of by reason of non-accuracy because of the difficulty of realizing the launching way friction in model.
The Auther has manufactured, for trial, a control unit which simulate the frictional force of launching way, by using in combination a low speed analogue computer, wire strain gauge type load cells and direct current servomotor. With the above simulator, the model test was carrid out on a 47, 000 T tanker 1/70 scaled model ship and the Auther ascertained the accuracy of the test by means of compering the model test data to the measured real ship motion, and established a method of model test of launching.

抄録全体を表示

New Method for removing of keel blocks by gun-powder is developed, and its safety and reliability is confirmed by the experiments for real blocks in the docks.
Labour cost is cut down to one tenth of conventional method.

抄録全体を表示

One-side automatic welding, a method of butt welding from one side only, has been successfully developed for thick plate of over 20 mm.
As to thin plate of about 10 mm, however, there existed many difficult problems. Major difficulties were on the distortion of plate and inaccuracy of edge preparation.
Some investigations has been carried out in our yard to solve this problems, and the new method has been established. In this method, thin flux layer is sandwitched between plate and copper strip, and submerged arc welding is used.
Certainty of back-side bead formation and soudness of welded joint are fully satisfactory.
This procedure has successfully been used in an assembling line of ship construction in the yard.

抄録全体を表示

This final report concerns the problem of deformation on the propulsion shafting.
First, from the results observed in actual vessels on berth, it will be shown that the amount of eccentricity of stern tube bossing when plotted against progress of work differs a little with the size of vessel. And the data on this eccentricity on one vessel may be applicable to its sister ship with a considerable accuracy.
Secondly, the relation between the amount of vessel's deformation such as stern rising and the vessel's scantlings, the berth foundation rigidity, and construction seasons will be discussed.
Regarding this problem, some experimental model tests and theoretical investigation were carried out. The conclusions are as follows;
(1) The amount of stern rising due to main deck butt welding is decreased as the vessel's breadth, depth, and plating thicknesses are increased among which the influence of depth is most predominant.
(2) The amount of vertical bending deformation is decreased as the supports and/or berth foundation on which the vessel is being built become more rigid.
(3) The amount of vertical bending deformation is increased to a far greater degree when the vessel is water born than on building berth.
It follows from the aboves that the small, fine, thin vessel, if she is afloat, tends to deform easily by main deck welding, while the large vessel hardly deforms.
(4) The climatic conitions hardly affect the amount of stern rising because the temperature difference between main deck and bottom is very small during summer and winter.
Finally, from the actual vessel's service records, it will be shown that ore carriers and oil tankers tend to deform sagging when they are loaded. It is presumed, however, that even this heavy sagging condition will have only little affect on the deformation of propulsion shafting if the vessel is built with engine aft and the loading is mainly on the tanks or holds in way of vessel's parallel part.

抄録全体を表示

Some proposals to use a high-speed computer for the fairing of ship lines have been made in recent years. And as many advantages of time and economy are expected, the method of practical application of the computer in ship line-fairing must be established before long.
Among some reports on this problem, we obtained suggestions from F. Theilheimers and developed a progromme of numerical calculation for practical use. This programme uses the values of station offset as input data and calculates the values of the frame offset as output data.
And as the application of the fairing method we have also developed a programme for the seam landing calculation.
In this report are given the outline of these programmes and an example of out put data of the fairing calculation.

抄録全体を表示

It is an important and essential fact to ensure the safety of ships during their service on the sea, as well as the improvement of their perfomances. Therefore, it has been concentrated the efforts to secure the reliable ship operation in the field of ship manufacturing industries as same as of ship operators.
Although it has been customary to employ the duplication of machinery elements installed in ships as a temporizing way for the above purpose so far, an idea of reliability makes its appearance as a new device that yields a lot of profits. Reliability is the probability of success for a given period of time. In other words, a practical form of reliability is a sort of relationship between failure and time.
In this paper, a statistical investigation study of field data of fifty seven vessels proves that the failure ratc characteristics of a marine propulsion plant are considered to depend upon many factors, such as a kind of main engine installed in a vessel (diesel engine, steam turbine engine and so forth), a type of engine (B & W, M. A. N., UEC and so forth), an engine manufacturing factory, the date manufactured, and a kind of ships (cargo liner, tanker, ore carrier and so forth). Also this paper shows each quantitative failure effect of machinery components on the main engine plant performances as it might be applied to future marine propulsion plants installed on board.

抄録全体を表示