• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.5
• /
• pp.422-429
• /
• 2011

The critical fluid velocity of cantilevered cylindrical shells subjected to internal fluid flow is investigated in this study. The fluid-structure interaction is considered in the analysis. The cantilevered cylindrical shell is supported intermediately at an arbitrary axial position. The intermediate support is simulated by two types of artificial springs: translational and rotational spring. It is assumed that the artificial springs are placed continuously and uniformly on the middle surface of an intermediate support along the circumferential direction. The steady flow of fluid is described by the classical potential flow theory. The motion of shell is represented by the first order shear deformation theory (FSDT) to account for rotary inertia and transverse shear strains. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. Numerical examples are presented and compared with existing results.

• Proceedings of the KSME Conference
• /
• 2000.11a
• /
• pp.665-670
• /
• 2000

The paper presents the dynamic instability of a disc brake pad subjected to distributed friction forces. A brake pad can be modeled as a beam with two translational springs. The study of this prototypical model is intended to provide a fundamental understanding of disc brake pad instabilities. Governing equations of motion are derived form energy expressions and their corresponding solutions are obtained by employing the finite element method. The critical distributed friction force and the instability regions are demonstrated by changing two translational spring constants. Finally, the changes of eigen-frequencies of a beam determining instability types are investigated for various combinations of two spring constants.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.905-906
• /
• 2006

This paper deals with the dynamic simulations and experiments of moving-coil linear actuator with/without spring. Dynamic simulation algorithm is established from the voltage and motion equation. Finally, for various values of frequency, dynamic simulation results for characteristics of current and displacement of moving-coil linear actuator with and without spring are presented and confirmed through the experiments.

• Journal of Power System Engineering
• /
• v.17 no.5
• /
• pp.38-43
• /
• 2013

In order to design a wave energy generating system, a 6-DOF analysis technique is applied to CFD analysis on of a floating body and the behavior is interpreted according to the nature of the incoming waves. A spring constant is adopted to control the motion of multi floating bodies and to calculate the total average power absorption. Three cases of different wavelengths namely 20D, 30D and 40D have been modeled to analyze the total average power absorption. The average power absorption not only varies with the position of the floating body but also varies with wavelength. From the results obtained, it is concluded that the maximum total average power absorption is 9W approximately in wavelength 30D and the minimum total average power absorption is 4.3W approximately in wavelength 40D.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.275-280
• /
• 2003

This paper discusses on the dynamic responsed of an elastically restrained beam under a moving mass of constant velocity. Governing equations of motion taking into account of all inertia effects of the moving mass were derived by Galerkin's mode summation method, and Runge-Kutta integration method was applied to solve the differential equations. Numerical solutions for dynamic deflections of beams were obtained for the changes of the various parameters (spring stiffness, spring position, mass ratios and velocity ratios of the moving mass). In order to verify the numerical predictions for the dynamic response of the beam, experiments were conducted. Numerical solutions for the dynamic responses of the test beam have a good agreement with experimental ones.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.503-507
• /
• 2004

The radiated sound pressure induced by low-velocity impact is obtained by solving the Rayleigh integral equation. This paper established the sound analysis procedure using impact analysis model. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. The impact response is computed using the spring-mass model. And the influence of damage on the sound pressure and impacted force history of laminated were investigated. The results show that both radiated sound pressure and impact force history are strongly influenced by damage on laminated.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.3
• /
• pp.168-174
• /
• 2012

This paper presents a bending propagating actuation using SMA (Shape Memory Alloy) spring for an effective shape transition of a flytrap-inspired soft morphing structure. The flytrap-inspired soft morphing structure is made from unsymmetric CFRP (Carbon Fiber Reinforced Prepreg) structure which shows bi-stability and snap-through phenomenon. For a thin and large curved bistable CFRP structure, SMA spring is more acceptable than SMA wire and piezoelectric actuator which used in previous investigations. A bending propagating actuation is proposed which can induce snap-through of the bi-stable CFRP structure effectively. From this research, effective shape transition of soft morphing structure is possible.

• Journal of Sensor Science and Technology
• /
• v.20 no.4
• /
• pp.249-253
• /
• 2011

This paper describes the fabrication and characteristics of vibration-driven electromagnetic energy harvester without spring to use at low frequency like a human body motion. The implemented energy harvester consists of NdFeB magnets, copper coil. The optimization of induced voltage was done by the various widths of coil, number of the turns, size of fixed and moving magnets and thicknesses of the cylinder. The fabricated energy harvester is capable of producing up to 15.0 $V_{pp}$ for basic model and 28.80 $V_{pp}$ for improved model at 5.0 Hz resonance frequency and 0.75 g acceleration level. The basic model and improved model are provided a maximum power of 6.375 mWand 25.831 mW at 1 KHz of load resistance in rectifier circuit.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.911-913
• /
• 2005

This paper deals with the dynamic analysis and experiments of moving-magnet lineal actuator with/without spring. On the basis of two dimensional(2-D) analytical solutions and experiments, control parameters are obtained. And then, dynamic simulation algorithm is established from the voltage and motion equation. Finally, for various values of frequency, dynamic simulation results for characteristics of voltage, current and displacement of moving-magnet linear actuator are presented and confirmed through the experiments. In particular, This paper makes the PWM voltage waveform using a DSP for bidirectional voltage drive

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.129-133
• /
• 2004

This paper is the result of a experimental study about non-linear one to one modal coupling of a flexible circular cantilever beam which was transversely excited with harmonic excitation. It was proved that 2 order jumping in out of plane was caused by jump phenomenon in in-plane of flexible circular cantilever beam, because of non-linear coupling. In addition, cantilever beam showed hardening spring characteristics in in-plane and softening spring characteristics in out-of-plane.