• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.17-24
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• 2011

It is reported that an intermittently rotating chamber system will improve the ratio of firepower to armament space in the case of mid-calibre automatic guns. However, the parallel index, which is a main component of the system, tends to be torsionally flexible due to the low lateral stiffness of cam followers on the index turret. This may cause the shaft system connecting the turret with the chamber prone to considerable residual torsional vibration so that serious misalignment problems occur during ammunition loading and firing processes. Herein, an electrorhelogical (ER) fluid actuator that can suppress such vibrations and the associated semiactive control algorithm are proposed. By mathematical modeling and computer simulations, the performance of the entire system is proved satisfactory.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.706-711
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• 2005

Torsional oscillations of a system incorporating a Hooke's joint are investigated by studying a simple similar nonlinear 2-degree-of-freedom model, which has linear and quadratic nonlinear parametric excitations. The simple system is identified to have the possibilities of primary, sub harmonic and combination resonances. The case of simultaneous primary and combination resonances is selected for perturbation analysis to have the reduced amplitude-equations of motion. The same procedure is applied to the system incorporating a Hooke's joint.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.580-586
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• 2016

The ultra-long stroke engine was developed to generate greater power at lower speeds than previous designs to enhance the propulsion efficiency. The torsional exciting force, on the other hand, was increased significantly. Therefore, it is possible to control the torsional vibration of its shaft system equipped with the fuel efficient ultra-long stroke engine by adopting a damper although the torsional vibration could be controlled adequately by applying tuning and turning wheels on the engine previously. In this paper, the dynamic characteristics of a viscous-spring damper used to control the torsional vibration of the corresponding shaft system are reviewed and then examined to determine what vibration characteristics might be used to optimize the viscous-spring damper. In some cases, operators of eco-ships have recently experienced the problem of delayed RPM acceleration. It has been suggested that the proper measures for controlling the torsional vibration in the shaft system should involve adjusting the design parameters of its damper determined by the optimum damper design theory to avoid the fatigue damage of shafts.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.321-328
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• 2015

In recent years, there has been an increasing demand to apply the new IACS(International Association of Classification Societies) standards for ice and polar-classed ships. For ice-class vessel propulsion system, the ice impact torque design criterion is defined as a periodic harmonic function in relation to the number of the propeller blades. However, irregular or transient ice impact torque is assumed to occur likely in actual circumstances rather than these periodic loadings. In this paper, the reliability and torsional vibration characteristics of a comparatively large six-cylinder marine diesel engine for propulsion shafting system was examined and reviewed in accordance with current regulations. In this particular, the transient ice impact torque and excessive vibratory torque originating from diesel engine were interpreted and the resonant points identified through theoretical analysis. Several floating ice impacts were carried out to evaluate torque responses using the calculation method of classification rule requirement. The Newmark method was used for the transient response analysis of the whole system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.4
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• pp.317-322
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• 2003

Torsional oscillations of a system incorporating a Hooke's joint are investigated by adopting a nonlinear 2-degree-of-freedom model. Linear and Van der Pol transformations are applied to obtain the equations of motion to which the method of averaging can be readily applied. Various subharmonic and combination resonances are identified with the conditions of their occurrences. Applying the method of averaging leads to the reduced amplitude- and phase-equations of motion, of which constant and periodic solutions are obtained numerically. The periodic solution which emerges from Hopf bifurcation point experiences period doubling bifurcation leading to infinite solution rather than chaotic solution.

• Journal of KSNVE
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• v.10 no.4
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• pp.655-661
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• 2000

Diesel power plant can be used as a power supplier for the isolated place where consumption of electric power is variable. The reason is that mobility and durability of diesel engine is superior to those of other thermal engines. However, there are some disadvantages for using these diesel engines such as bigger vibratory excitation force comparing to the others, which result from high combustion pressure of cylinders and inertia force of piston reciprocating masses. In this paper, control and optimization of torsional vibration of 12K90MC-S engine for diesel power plant using uneven crank angles is identified by theoretical analysis and vibration measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.110-115
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• 1995

In this paper, the problem of non-linear torsional oscillation of a system incorporating a Hooke's joint is studied. Classical perturbation methods including higher order averaging and bifurcation theory are adopted for analysis. The equation of motion derived by Porter[1] is presented and the type of the system is identified. It has been found that two important cases deserve extensive study. Method of higher order averaging which is a main research tool in this study is introduced briefly. The averaged equations are studied analyticallyand numerically and the method of averaging has been found to be effective to study complex non-linear system.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.276-283
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• 2003

While designing a torsional shafting with various gear-branched systems, it is very important for system designers to obtain critical speeds accurately and easily. The author has studied the transfer stiffness coefficient method (TSCM) as a structural analysis algorithm. In this paper, the TSCM is applied to the computation of critical speeds for torsional shafting with gear-branched systems. The accuracy of the present method is confirmed by comparing with the results of the finite element method.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.107-113
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• 1995

Using the mathematical model of the torsional vibration in spindle system with magnetic coupling, which was proposed in the paper of dynamic analysis of spindle system with magnetic coupling(l), we derive the equations of the motion and the form of the derived equations represents Duffing equation. Numerical analyses are executed in many conditions, namely the various types in magnetic coupling, changes of the gap between driver and follower. To verify the results of the therorectical analyses, a precision dynamic drive system is manufactured and methods of the test to measure the torsional vibration of the spindle system with magnetic coupling are presented ad thests in various conditions are carried out.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.60-71
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• 2000

When the crankshaft of Diesel engine has more than 3 throws which are arranged in a different plane its vibration induces coupled motions especially the coupled torsional and axial vibration. Nowadays the torsional vibration which is influenced rather weak than axial one can be theoretically calculated fairly accurately but theoretical calculation results of the axial vibration which is influenced strongly from torsional vibration is not so good. To get accurate calculation results of axial vibration coupled axial-torsional vibration must be treated. in this investigation coupled effects of vibration of Diesel engine propulsion shafting are analyzed theoretically and some more simple calculation methods are also studied. On this first report effects of coupling on natural frequencies and their modes are mainly studied setting the each mass in 4 degrees of freedom. later this problem may be studied again by setting each mass as 6 degrees of freedom.