• Journal of Advanced Marine Engineering and Technology
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• 제10권4호
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• pp.41-49
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• 1986

With the trend towards high propulsive level, increasing ship's dimensions and heavier shaft systems supported by the hull structure of relatively stiffness in modern ships, transverse vibrations of propulsion shaft system have become one of the problems that should be predicted in the early design stage. Regarding transverse vibrations, coupling terms such as oilfilm, gyroscope and hydrodynamic effect of the propeller exist between the vertical and horizontal vibration, furthermore for the shaft system with strut and bossing its physical properties incorporated with hull structure must be considered. In order to predict the transverse vibratory condition of the propulsion shaft and take some appropriate countermeasures, it is necessary to make a fairly strict estimation of the vibratory behaviours of it. In this paper, theoretical approach using the finite element method is investigated to calculate natural frequencies and vibration modes for coupled free transverse vibrations of shaft system in two planes. Based on the method investigated a digital computer program is developed and is applied to calculate the above-mentioned vibrations of an experimental model shaft system. The results of the calculation are compared with those of the experimental measurements and they show an acceptable agreement.

• Journal of KSNVE
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• 제4권3호
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• pp.365-375
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• 1994

Periodic longitudinal vibrations of a video and audio tape and the like used for transducing pictures and sounds may be induced by self-excited vibrations which are caused by frictions against the heads and guides, and their eccentricity, noncircularity or irregularity. It is important to analyze the longitudinal vibration of a tape because it causes distortions of a reproduced signal. It is difficult to measure directly the longitudinal vibration. In this paper a method estimating longitudinal vibration using impulse responses in the transverse direction is presented. And, the parameters boundary domain where the transverse and longitudinal vibration can be decoupled is introduced. In the domain where the both vibrations are decoupled, analytic methods using frequency characteristics and transient responses of the transverse vibration, respectively, are presented. The time domain method predicted more exactly the instantaneous phase of the longitudinal vibration than frequency domain method did.

• Journal of Advanced Marine Engineering and Technology
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• 제7권1호
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• pp.49-63
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• 1983

Coupled transverse shaft vibrations have become the target of great concern in high powered ships such as container ships. Due to increasing ship's dimensions and high propulsive power, resonance frequencies of the propeller shaft system tend to decrease and can appear in some cases within the operating speed range of engine. In this connection, the coupled free transverse vibrations of shaft system in two planes are theoretically investigated. This shaft system carries a number of discs and is flexibly supported by a number of bearing stiffness are considered for the calculation. Transfer matrix method is applied to calculate the shaft responses in both planes. A digital computer program is developed to calculate the shaft responses of the coupled transverse vibrations in two planes. An experimental model shaft system is made. It is composed of a disc, shafts, ball bearings thrust bearings and flexible bearing supports. The shaft system is excited by an electrical magnet, and shaft vibration responses in two planes are measured with the strain gage system. From these measurements, the natural frequencies of the shaft system in both planes are found out. The developed program is also used to calculate the shaft vibration responses of experimental model shaft system. From the results of these calculations, the natural frequencies of shaft system in two planes are derived. Theoretical predictions of model shaft natural frequencies show good agreements with its esperimental measurements.

• Proceedings of the KSR Conference
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.13-17
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• 2010

This presentation examines the characteristics of torsional vibration in axisymmetric out-of-plane vibrations of an annular Mindin plate. The out-of-plane vibration of circular or annular plates have been investigated since a long years ago by many researchers. When the classical Kirchhoff plate theory neglecting the effect of transverse shear deformation is applied to a thick plate, its out-of-plane natural frequencies are much different from reality. And so, since Minlin presented a plate theory considering the effect of rotary inertia and transverse shear deformation, many researches for the out-of-plane natural vibration of circular or annular Mindin plates have been performed. But almost all researchers missed the torsional vibration due to transverse shear deformation in axisymmetric out-of-plane vibrations of the circular or annular Mindin plate. Therefore, in this presentation, we verify the existence of torsional vibration of an annular plate and present the natural frequencies of an annular plate with free outer boundary surface.

• Structural Engineering and Mechanics
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• 제55권2호
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• pp.281-298
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• 2015

In this study, nonlinear transverse vibrations of tensioned Euler-Bernoulli nanobeams are studied. The nonlinear equations of motion including stretching of the neutral axis and axial tension are derived using nonlocal beam theory. Forcing and damping effects are included in the equations. Equation of motion is made dimensionless via dimensionless parameters. A perturbation technique, the multiple scale methods is employed for solving the nonlinear problem. Approximate solutions are applied for the equations of motion. Natural frequencies of the nanobeams for the linear problem are found from the first equation of the perturbation series. From nonlinear term of the perturbation series appear as corrections to the linear problem. The effects of the various axial tension parameters and different nonlocal parameters as well as effects of different boundary conditions on the vibrations are determined. Nonlinear frequencies are estimated; amplitude-phase modulation figures are presented for simple-simple and clamped-clamped cases.

• Steel and Composite Structures
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• 제38권3호
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• pp.281-291
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• 2021

An equivalent single-layer theory (EST) is put forward for analyzing free vibrations of steel-concrete composite beams (SCCB) based on a higher-order beam theory. In the EST, the effect of partial interaction between sub-beams and the transverse shear deformation are taken into account. After using the interlaminar shear force continuity condition and the shear stress free conditions at the top and bottom surface, the displacement function of the EST does not contain the first derivatives of transverse displacement. Therefore, the C0 interpolation functions are just demanded during its finite element implementation. Finally, the EST is validated by comparing the results of two simply-supported steel-concrete composite beams which are tested in laboratory and calculated by ANSYS software. Then, the influencing factors for free vibrations of SCCB are analyzed, such as, different boundary conditions, depth to span ratio, high-order shear terms, and interfacial shear connector stiffness.

• Proceedings of the KSR Conference
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1689-1694
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• 2011

There are increasing customer's needs for safe operation and comfort of trains for the passengers as trains are getting fast and developed with advanced components. To meet the needs we developed the system which is able to prevent possible risk elements by transverse vibrations during the train operation. System records the amplitude data of trains vibration and location data from GPS antenna in real time. The system is composed of 5 different functioning modules as following GCPU, GGWD, GIFD, GAID and GPSD. GAID module is detecting amplitude value of vibration which is sensed by bogie hunting sensor's. GFID gets location information where vibration data is detected with GPS Antenna. Once those data is prepared, GCPU testify it's amplitude and decides whether it send those data. When it sends those recorded data, those data are sent to control unit by MVB communication. we expect that this information will help operation and maintenance engineers improve the safety train services. This paper explains train transverse Vibrations data recording system and its major functions which can measure the amplitude of trains's data during the operation and introduces the configuration for the system setup.

• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.87-93
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• 2002

In this study, basic concepts of magnet were introduced, and dynamic characteristics of magnet coupling were explored. Based on these characteristics, it was proposed how to analyze transverse and torsional vibrations of a spindle system with magnet coupling. Proposed theoretical approaches were applied to a precision power transmission system machined for this study, and the transverse and torsional vibrations were simulated. The force on magnet coupling was shown as a form of nonlinear function of the gap and the eccentricity. Also, the form of torque transmitted by magnet coupling was considered as a sinusoidal function. Main spindle connected to a coupling of a follower part was assumed to be a rigid body. Nonlinear partial differential equation was derived to be as a function of angular displacement. By using the equation, torsional vibration analysis of a spindle system with magnet coupling was performed. Free and forced vibration analyses of a spindle system with magnetic coupling were explored by using FEM.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2258-2264
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• 2004

This article described the numerical investigation of shear-thinning blood flow characteristics when subjected to longitudinal and transverse vibrations and delineated the underlying mechanisms of the flow rate enhancements, respectively. In order to fully consider the mechanical vibrations of the capillary, a moving wall boundary condition was adopted. The present numerical results showed that the longitudinal vibration caused a significant increase of wall shear rates, which resulted in a decrease of viscosity and the subsequent increase of flow rates. However, the shear rate for the transverse vibration was slightly increased and the calculated flow rate was underestimated comparing with the previous experimental results.

• Structural Engineering and Mechanics
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• 제44권4호
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• pp.521-538
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• 2012

In this study, the transverse vibrations of an axially moving flexible beams resting on multiple supports are investigated. The time-dependent velocity is assumed to vary harmonically about a constant mean velocity. Simple-simple, fixed-fixed, simple-simple-simple and fixed-simple-fixed boundary conditions are considered. The equation of motion becomes independent from geometry and material properties and boundary conditions, since equation is expressed in terms of dimensionless quantities. Then the equation is obtained by assuming small flexural rigidity. For this case, the fourth order spatial derivative multiplies a small parameter; the mathematical model converts to a boundary layer type of problem. Perturbation techniques (The Method of Multiple Scales and The Method of Matched Asymptotic Expansions) are applied to the equation of motion to obtain approximate analytical solutions. Outer expansion solution is obtained by using MMS (The Method of Multiple Scales) and it is observed that this solution does not satisfy the boundary conditions for moment and incline. In order to eliminate this problem, inner solutions are obtained by employing a second expansion near the both ends of the flexible beam. Then the outer and the inner expansion solutions are combined to obtain composite solution which approximately satisfying all the boundary conditions. Effects of axial speed and flexural rigidity on first and second natural frequency of system are investigated. And obtained results are compared with older studies.