• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.240-245
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• 2004

A modeling method for the modal analysis of a rotating composite cantilever beam is presented in this paper. Linear differential equations of motion are derived using the assumed mode method. For the modeling, hybrid deformation variables are employed and approximated to derive the equations of motion. Symmetrical laminated composite beams are considered to obtain the numerical results. The effects of the dimensionless angular velocity, the hub radius and the fiber orientation angle on the variations of modal characteristics are investigated.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.107-114
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• 2007

In this paper, the equations of motion by which the natural vibration of rotating thick ring can be analyzed accurately are presented. These equations are derived from the theory of finite deformation and the principle of virtual work. The effects of variation in curvature across the ring cross-section can be considered in these equations. The ring models are called as thick ring model and thin ring model respectively as the effects of variation in curvature are considered or neglected. The radial displacement of ring which is rotating at constant angular velocity is determined by a non-linear equation derived from the principle of virtual work. The equations of the in-plane and out-of-plane vibrations at disturbed state are also formulated from the principle of virtual work. They can be expressed as the combination of the radial displacement at the steady state and the disturbed displacements about the steady state. The natural vibrations of rings with different thickness are analyzed by using the presented ring models and 3-dimensional finite element method to verify accuracy of the presented equations of motion. Its results are compared and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.226-232
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• 2006

This paper presents the dynamic analysis of an impulsively forced rotating cantilever beam with rigid body motion. The transient response induced by the impulsive force and the rigid body motion of the beam are calculated using hybrid deformation variable modeling with the Rayleigh-Ritz assumed mode methods. The stiffness variation effect due to the rigid body motion of the beam is considered in this study Also, the effects of the impulsive force position and the angular velocity on the transient responses of the beam are investigated through numerical works.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1052-1057
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• 2010

Dynamic stability of rotating blade considering gravity effect is investigated in this paper. Equations of motion for the beam is derived by employing hybrid deformation variable method and transformed into dimensionless form. The present modeling method is verified by RecurDyn. Stability diagrams are presented to show the influence of the configuration of the beam and angular velocity on the dynamic stability by applying Floquet's theory. Since the natural frequencies are varied when the blade has rotating motion, it is found that relatively large unstable regions exist approximately 1.1 times as high as the first bending natural frequency and half of the sum of first and second bending natural frequency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.742-751
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• 2013

The vibration analysis of a rotating cantilever beam made-up of functionally graded materials is presented based on Timoshenko beam theory. The material properties of the beams are assumed to be varied through the thickness direction following a simple power-law form. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of power-law exponent, angular speed, length to height ratio and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.457-460
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• 2014

Precession coefficient is defined by the ratio of the angular rate or rotational angle of the standing wave formed in an elastic resonator with respect to that of the platform. In this paper the precession of a hemispherical resonator due to Coriolis' effect is studied through Rayleigh-Ritz's method and Lagrangian Mechanics when the resonator undergoes Rayleigh's mode deformation. The calculation result was compared with studies by other researchers.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.10-16
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• 2009

Modal characteristics of a cracked beam with a concentrated mass undergoing rotational motion are investigated in this paper. Hybrid deformation variables are employed to derive the equations of motion of a rotating cantilever beam. The flexibility due to crack, which is assumed to be open during the vibration, is calculated basing on a fracture mechanics theory. To obtain more general information, the equations of motion are transformed into a dimensionless form in which dimensionless parameters are identified. The effects of the dimensionless parameters related to the angular speed, the depth and location of a crack and the size and location of a concentrated mass on the modal characteristics of the beam are investigated numerically.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.263-265
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• 2009

In this study, ultrafine grained (UFG) oxygen free high conductivity copper (OFHC Cu) having two different grain morphologies, one the severely elongated and the other the equiaxed, was prepared by equal channel angular pressing (ECAP) with routes A and $B_c$, respectively. The results of quasi-static tensile tests at $10^{-1}\;s^{-1}$ and $1\;s^{-1}$ and dynamic compression tests at $10^3\;s^{-1}$ order revealed that the equiaxed UFG Cu exhibited higher strength and less ductility compared to the elongated one. The difference of the plastic flow characteristics between the two were rationalized by considering their dislocation mean free length based on the orientation relationship between the possible slip planes and the loading direction.

• Advances in materials Research
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• v.8 no.2
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• pp.83-102
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• 2019

The present research deals with the time harmonic deformation in transversely isotropic magneto thermoelastic solid with two temperature (2T), rotation and without energy dissipation due to inclined load. Lord-Shulman theory has been formulated for this mathematical model. The entire thermo-elastic medium is rotating with a uniform angular velocity. The Fourier transform techniques have been used to find the solution to the problem. The displacement components, stress components and conductive temperature distribution with the horizontal distance are computed in the transformed domain and further calculated in the physical domain using numerical inversion techniques. The effect of time harmonic source and rotation is depicted graphically on the resulting quantities.

• Advances in materials Research
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• v.7 no.2
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• pp.105-118
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• 2018

Magnesium and its alloys are attracted towards all engineering applications like automotive, marine, aerospace etc. due to its inherent high strength to weight ratio. But, extensive use of Mg alloys is limited to the current scenario because of low wear and corrosion resistance behavior. However, equal channel angular press is one of the severe plastic deformation technique which has been effective method to improve the wear and corrosion resistance by achieving fine grain structure. In this study, the effect of grain refinement on wear and corrosion resistance of AZ80 Mg alloys were investigated. The wear behavior of the coarse and fine-grained Mg alloys was examined through $L_9$ orthogonal array experiments in order to comprehend the wear behavior under varies control parameters. It was shown that ECAPed alloy increased the wear and corrosion resistance of the Mg alloy through the formation of fine grain and uniform distribution of secondary ${\beta}-phase$. Also, the performance of AZ80 Mg alloy for these changeswas discussed through SEM morphology.