Journal of Zosen Kiokai
Online ISSN : 1884-2054
ISSN-L : 1884-2054
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Volume 1938, Issue 63
Displaying 1-11 of 11 articles from this issue
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  • Some Considerations on the Effective Height of Coaming Plates
    Investigations on the Stress Concentration at Discontinuities in Ship Structures. Report 4
    T. Ohta
    1938 Volume 1938 Issue 63 Pages 15-34
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_15
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    In my previous paper [J. of Zosen Kiokai, vol. 62 (1938)], the effect of coaming plates on the stress distribution in a perforated plate were treated, but nothing about the effective height of coaming plates. So the present paper deals with said latter points analytically, and some practical examples are solved by using the derived formulae. The conclusion is to give an effective height of coaming plates, in case of a perforated plate under all round tension, by the following expression,
    he'/r0=1/1-νt'/t1-1-ν/1+ν[2γ/γ{λ+(1-ν)}+1.52λ3/2χ]/1+[2γ/γ{λ+(1-ν)}+1.52λ3/2χ]
    where he'=effective height of a coaming plate.
    r0=radius of a circular hole.
    t'=thickness of a perforated plate.
    t=thickness of a coaming plate.
    ν=Poisson's ratio.
    γ=t'/r0. λ=t/r0.
    χ=tanαsech2α+tanhαsec2α/sech2α+sec2α,
    in which α=1.316l/√<r0t>, 2l being the total height of a coaming plate.
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  • Flexural Stresses in a Plate with a Flanged Circular Hole.
    Investigations on the Stress Concentration at Discontinuities in Ship Structures. Report 5
    [in Japanese]
    1938 Volume 1938 Issue 63 Pages 35-53
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_35
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    The object of the present work is to study the effect of coaming plates on the flexural stresses in a deck plating. Although flexural stresses in a plain perforated plate were dealt with some years ago by W. G. Bickley, I. Nakayama and J. N. Goodier, those problems with a flanged circular hole seem to have never been treated. The solution of the problem is easily obtained by using the results of plane stresses described in my previous paper [J. of Zosen Kiokai, Vol. 54 (1934)].
    In case of the infinitely strong coaming plate, the solution entirely agreed with that of a plain perforated plate under some corresponding forces. The first part of this paper dea's with mathematical analysis of the problem and the 2nd part numerical calculations for practical examples. As a supplement, the correspondency between a perforated plate under some plane forces and a bent plate clamped at the rim of a hole is treated.
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  • Theoretical Investigation on Plastic Bending and Residual Stress due to it of Mild Steel Beam
    Kazuo Terazawa
    1938 Volume 1938 Issue 63 Pages 55-103
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_55
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    On the assumption that the stress-strain relation in the tension test holds in the case of bending, the general theory of the plastic bending of a mild steel beam having a section, which is unsymmetrical to the elastic neutral axis, was developed. This theory was applied to some special cases of practical interest. As an example, trapezoidal section beam and rectangular section beam were numerically treated, and the moment-curvature relations and the stress-distributions in these cases were graphically shown, using the ratio of the upper yield point to the lower one as a parameter.
    In the latter part, the general theory on residual stress and residual curvature due to plastic bending was derived, on the assumption that the stress-strain relation of plastically strained rod at unloading holds in the case of bending. As an example, the application of this theory to the trapezoidal section beam and rectangular section beam were treated. On the basis of these applied theories, the numerical value of residual stress and curvature of these beams were obtained. In consequence of these calculations, it was noticed that the residual stress on the tension-side of beam was negative and the positive residual stress acted on the compression-side.
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  • An Approximate Method of Estimating the Requisite Horse-power of Propelling Machineries of Cargo Ships.
    Masao Yamagata
    1938 Volume 1938 Issue 63 Pages 105-124
    Published: 1938
    Released on J-STAGE: May 30, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_105
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    The easy approximation of the requisite amounts of powers of propelling machineries is always quite necessary in the early stages of ship design. In the present Paper, they are given corresponding to the adopted standards of cargo ship forms and propellers, and supplemented with correctional values for differences between standards and those which may apply to a particular vessel.
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  • On the Air Drawing of a Rudder
    Shigeru Akazuki
    1938 Volume 1938 Issue 63 Pages 125-129
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_125
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    Should the design not be satisfactory, a rudder is liable to draw-in air behind its plate, when the vessel is travelling at high-speed with a large rudder angle, resulting in the circle becoming larger.
    Experiments with a self-propelling model boat were conducted with the position and immersion of the rudder changed, in order to ascertain the position at which the rudder draws-in the air. The most sat sfactory methods for compensating for it were investigated and determined.
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  • On the Normal Pressure and Centre of Pressure of a Rudder
    Shigeru Akasaki
    1938 Volume 1938 Issue 63 Pages 131-146
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_131
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    By open and behind (towing straight and turning) experiments with a series of rudders A, B and D, the following experimental formula for normal pressure was obtained:-
    Pa=67.3AV12{sinα+1/12.6sin2χ+n/180sin(180/nα)-mn/360(360/nα)}.
    Either Jössel's or the following formula can be used for the centre of pressure:-
    x/b=0.2+0.3sinα.
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  • On the Cable Layer “Toyo-Maru.”
    Kikuo Takahasi
    1938 Volume 1938 Issue 63 Pages 147-158
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_147
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    This paper is a general description of the cable layer “Toyo-Maru”, which was recently built by Kawasaki Dockyard Co., Ltd., Kobe, for the Department of Communication of our Government.
    In the former part of this paper, the general arrangement of the ship and construction of the hull are refered; and in the next part, the cable handling apparatus and their arrangement, to which various installations are properly deviced and attention is paid to make them fit to the modern submarine cable.
    In the latter part, the propulsive machinery is described. It is worthy of note that the new ship is provided with two sets of double reduction geared turbine and one set of Voith Schneider system of propulsion; the latter, however, is prepared rather for the purpose of manoeuvering the ship during cable laying operation than for the propulsion of the ship. The principal dimensions are as follows.
    Length over all……121.02m Load draught……6.34m
    Length between perpendiculars 102.25m Gross tonnage……3, 718.73t
    Breadth moulded……14.75m Net tonnage……1, 819.76t
    Depth moulded to upper deck……8.25m
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  • The Vibration Damping of a Ship in her Moving State
    Katsutada Sezawa, Wataru Watanabe
    1938 Volume 1938 Issue 63 Pages 159-170
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_159
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    As a continuation of the authors's last investigation concerning the causes of the vibration damping of a ship, the same authors newly found that there is an additional vibration damping of a ship in her moving (ahead) state, -the damping originating from the movement of the ship's hull relative to the water. Using a circulation water tank, the authors conducted model experiments of free as well as forced vibrations, from which it was ascertained that the vibration damping enormously increases with increase in water velocity relative to the model, and, furthermore, that the results obtained from separate methods of tests, namely forced vibration test and free vibration test, fairly agree. The same results were confirmed by means of a statical hydrodynamic test, though the idea about it is rather inexact. From the results of experiments, the damping constants of a flat surface vibrating normal to water stream were deduced, from which it was possible for the authors to estimate, in speculation, the damping coefficients of an actual ship moving at various speeds. It was shown that in the case of an actual ship, the estimated theoretical damping coefficient is of the order of magnitude as the actual cne, particularly in moving-ahead condition, at low speed, of the same ship.
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  • On the Mechanical Properties of the Welded Steel
    Takejiro Ujiiye
    1938 Volume 1938 Issue 63 Pages 171-198
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_171
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    In this paper the author tried to determine what is the mechanical properties, such as tensile and compressive strength and impact resistance of welded steel at room temperature.
    The author may question the necessity for these investigations, believing that our knowledge of the properties of welded steel at room temperature predicts what the properties of the same metal would be at lowered and elevated temperature range from -40°C to 600°C.
    The absorption of nitrogen is one of the most important of the physical properties of welded steel.
    The author takes up practical aspects of the influence of nitrogen on the quench and edge-hardening.
    Finally the author deals with forging properties of the metal at higher temperature and shows graphically the results of edge-hardening of the same metal at very low temperatures which were created by ice-water, coagulated mercury and liquid-air respectively.
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  • Two Patent Systems of Simplified Hull Form.
    C. Ono
    1938 Volume 1938 Issue 63 Pages 199-213
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_199
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  • On“Ryofu Maru”a Diesel Ship
    Shozo Asakawa
    1938 Volume 1938 Issue 63 Pages 215-223
    Published: 1938
    Released on J-STAGE: May 29, 2007
    DOIhttps://doi.org/10.2534/jjasnaoe1903.1938.63_215
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    “Ryofu Maru”is the first observation ship of ocean in Japan; which was built by Harima Dock Yard Co. Ltd. That was equipped with two Shinko Sulzers of Kobe Iron Works and with all instruments for Observatory and Oceano-graphic.
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