JOURNAL OF THE MARINE ENGINEERING SOCIETY IN JAPAN
Online ISSN : 1884-4758
Print ISSN : 0388-3051
ISSN-L : 0388-3051
Volume 18 , Issue 12
Showing 1-17 articles out of 17 articles from the selected issue
  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 891-905
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 906-910
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 911-917
    Published: December 01, 1983
    Released: May 31, 2010
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 918-927
    Published: December 01, 1983
    Released: May 31, 2010
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 928-935
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 936-939
    Published: December 01, 1983
    Released: May 31, 2010
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  • [in Japanese], [in Japanese]
    1983 Volume 18 Issue 12 Pages 940-948
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 949-956
    Published: December 01, 1983
    Released: May 31, 2010
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  • [in Japanese], [in Japanese], [in Japanese]
    1983 Volume 18 Issue 12 Pages 957-961
    Published: December 01, 1983
    Released: May 31, 2010
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  • [in Japanese]
    1983 Volume 18 Issue 12 Pages 962-967
    Published: December 01, 1983
    Released: May 31, 2010
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  • Takao Azuma, Shinobu Saito, Eiichi Nakagawa
    1983 Volume 18 Issue 12 Pages 968-974
    Published: December 01, 1983
    Released: May 31, 2010
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    The vibration characteristics of rotating shaft system should be computed considering the dynamic stiffness of bearing foundation, especially if this stiffness is rather low. But the accurate characteristics of such a system has not been computed, as far as known, so that the dynamic stiffness of the bearing foundation can have hardly been obtained.
    In this paper, a method to estimate the dynamic stiffness of bearing foundations by measuring their compliances dynamically is presented. On the other hand, the critical speeds and damping ratios of a model shafting system, consists of shaft, bearings and their foundations, was measured on the testing rig, and was compared to the estimated ones by using the dynamic stiffness obtained by the above mentioned method.
    There is good agreement between the measured and estimated ones, though the stiffness of bearing foundations of the testing rig is relatively low compared with actual machinaries. It is expected that the method described in this paper is useful to predict the vibration characteristics of rotating shaft system of actual machineries.
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  • Shoichi Iwamoto, Tohru Yonezawa, Yasunori Mukawa
    1983 Volume 18 Issue 12 Pages 975-981
    Published: December 01, 1983
    Released: December 08, 2010
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    In zweitem Bericht wurden die Meßergebnisse vom Charakter des Viskose-Drehschwingungs-dämpfer beim schnellaufenden Dieselmotor betrachtet. Im diesen Bericht werden die Drehschwingungsmessungen an einem langsamlaufenden Dieselmotor gemacht, der mit den Viskose-Drehsthwingungsdämpfern der mäßigen Größe ausgerüstet ist, wenn man die Viskosität des Wirköles im Dämpfer vielerlei wechselte, und daraus wird der Charakter des Viskose-Drehschwingungsdämpfers beim langsamlaufenden Dieselmotor ermittelt. Der Schluil lautet wie folgend:
    1) Die Meßergebnisse vom Schwingviskometer, d.h. die Werte von tan δ' in den Abb. 8-11 des ersten Berichtes sind auf den Original-Viskosedrehschwingungsdämpfern beim langsamlaufenden Dieselmotor mit den Resonanzfrequenzen im Gebiet j=26-30 Hz beinahe übertragbar.
    2) Wenn man auch für beide schnell-und langsamlaufenden Dieselmotor den optimalen Dämpfungsbeding des Dämpfers mit χ22=1, 0 oder χ+α=1, 0 irgend denkt, dann hat dieser Unterschied jedenfalls in der Tat kein Problem. Hier ist χ dimensionslose Dämpfungswiederstands-konstante und α dimensionslose Federkonstante. Aber aus den früheren und diesen Experimenten paßt es sich besser, daß man im allgemeinen für die Viskose-Drehschwingungsdämpfer bei Mehrzylindermotoren den optimalen Dämpfungsbeding mit χ22=1, 0 denkt.
    3) Das Verhältnis zwischen χ und α erhiert man wie folgend.
    a) Für den schnellaufenden Motor (Resonanzfrequenzen fn=160-190Hz) ; α=3, 45χ3.6.
    b) Für den langsamlaufenden Motor (Resonanzfrequenzen fn=26-30Hz) ; α=0, 2χ1.7.
    4) Wenn die Dämpfermasse an beide schnell-oder langsamlaufenden Dieselmotor nicht zu klein ist, hat die Motordämpfung auf die Gräße der Dämpfungsamplitude keinen Einfluß.
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  • 1983 Volume 18 Issue 12 Pages 980
    Published: 1983
    Released: May 31, 2010
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  • Tohru Yonezawa, Gensi Yasuma
    1983 Volume 18 Issue 12 Pages 982-988
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
    Various experimental equations (designated as experimental equations hereinafter) have hitherto been applied on torsional stiffness calculations of crank shaft in the form of equivalent length. However, all of these experimental equations had been obtained more than 50 years ago. Recent engines become substantially different from engines of those days in respect of weight, speed and so on, and characteristics of crank shaft are also conspicuously changed. Accordingly, experimental equations produce large errors and have little universality for diversification of crank shaft shapes. Therefore, the equivalent length is now obtained from actually operated engine data or estimations from an engine having similar characteristics, thus an experimental equation being used with its correction factors properly determined by an engineer in charge.
    In this study, first, torsional stiffness of crank shaft was dynamically measured by the use of a vibrator, and good coincidence between the measured results and values calculated back from measured results of torsional vibration in an actual engine, was made clear. Then, torsional stiffnesses were measured with the shape of the crank shaft changed variously, and simultaneously torsional stiffnesses were obtained by the FEM, thus calculation accuracies of more than and inclusive 96% being obtained with respect to actually measured results for all shapes of crank shafts.
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  • Koichi Tsuda
    1983 Volume 18 Issue 12 Pages 989-992
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
    On board a turbine ship equipped with a ducted propeller going ahead at a diminishing speed following crash stop astern operation, big noise occurred at its final reduction gear box. It was caused by collision of the bull gear with the final pinions of the high pressure turbine shafting, while no one had clarified the reason why they so randomly as well as violently collide at the speed range. The author describes some of the given data and his reasoning in the past.
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  • Masao Sugimoto, Hideo Ohashi, Toshihiro Takenaka
    1983 Volume 18 Issue 12 Pages 993-998
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
    In recent years, two-stroke slow speed diesel engines with long stroke, large bore and a small number of cylinders are on the increase, to get higher propulsion efficiency of the engine and the propeller and less maintenance of the engine.
    Diesel engines with a small number of cylinders, however, have some kinds of vibration problem. Torsional vibration problem is one of them. In case of five-cylinder engines, for instance, 1-node 5th-order torsional vibration is often dangerous for normal shafting design, so some countermeasure is necessary. In such cases, ‘the tuning disk with hydrodynamic damping’ is useful.
    Of course, to get the optimum tuning for each different shafting, computer aided design (C.A.D.) is very useful.
    Using Geislinger damper, optimum tuning can be obtained by choice of suitable elasticity and damping.
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  • Kunihiro Mitsuhashi, Kazuo Morita
    1983 Volume 18 Issue 12 Pages 999-1004
    Published: December 01, 1983
    Released: May 31, 2010
    JOURNALS FREE ACCESS
    Isolation properties of antivibration mounts were tested with models of the machinery casing and the ship-like structure. The mobilities of the machinery base plate and foundation bed plate of those models were found to be approximated to rigid masses at low frequencies and infinite plates for higher frequencies compared with the first local plate resonance.
    Using these results and regarding resilient mount as massless spring, isolation properties of the soft and hard resilient mounts and the reduction method of the input vibration power to the ship structure were investigated.
    In addition, a new type of isolation system in which a damping plate was inserted between the upper and the lower resilient mounts was devised and its superior vibration isolation effect was verified experimentally with the above mentioned models.
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