• Ocean Systems Engineering
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• v.5 no.3
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• pp.221-243
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• 2015

This paper compares simplified and finite element method (FEM) models for tower and blade in dynamic coupled analysis of floating wind turbine. A SPAR type wind turbine with catenary mooring lines is considered in numerical analysis. Floating body equation is derived using boundary element method (BEM) and convolution. Equations for mooring line, tower and blade are formulated with theories of catenary, elastic beam and aerodynamic rotating beam, respectively and FEM is applied in the formulation. By combining the equations, coupled solutions are calculated. Tower or blade may be assumed rigid or lumped body for simplicity in modeling. By comparing floating body motions, mooring line tensions and tower stresses with the simple model and original FEM model, the effect of including or neglecting elastic, rotating and aerodynamic behavior of tower and blade is discussed.

• Coupled systems mechanics
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• v.8 no.1
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• pp.19-38
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• 2019

The influence of torsional rigidity of hinged flexible appendage on the linear dynamics of flexible spacecrafts with liquid on board was analyzed by considering the spacecraft's main body as a rigid tank, its flexible appendages as two elastically supported elastic beams, and the onboard liquid as an ideal liquid. The meniscus of the liquid free surface due to surface tension was considered. Using the Lagrangian of the spacecraft's main body (rigid tank), onboard liquid, and two beams (flexible appendages) in addition to assuming the system moved symmetrically, the coupled system frequency equations were obtained by applying the Rayleigh-Ritz method. The influence of the torsional rigidity of the flexible appendages on the spacecraft's coupled vibration characteristics was primary focus of investigation. It was found that coupled vibration modes especially that of appendage considerably changed with torsion spring parameter ${\kappa}_t$ of the flexible appendage. In addition, variation of the main body displacement with system parameters was investigated.

• Journal of the Korea Computer Industry Society
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• v.2 no.6
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• pp.853-858
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• 2001

When an absolute elastic collision occurs between a motion body and the another body inside a closed space, according to the current physical law and thus a computer graphical expression, it is defined that the center of mass of the closed space is not moved. This paper defines a physical law which includes a minor facts of the center of mass of a closed space moves during an absolute elastic collision occurs between a motion body and another body inside a closed space. The law defined in this paper has been verified using approximate lab equipments, and using this, graphical expression models and mathematical expressions for an absolute elastic collision between two bodies inside a closed space are del ed. When the minor effects of the center of mass moves is applied to the multi-body dynamic simulation program or haptic program, more accurate motion could be expressed. This definition can also be applied to an animation movie or other graphical motion expression for more realistic expression.

• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.101-105
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• 2006

In this paper, a disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of the elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disks to bond onto both surfaces of an elastic disk, respectively. As a result, the diameter of the elastic body is increased and the resonant frequency is decreased. The resonant frequency of the stator is about 92 kHz, which is composed with piezoelectric ceramic disks of 28 mm in diameter and 2 mm in thickness, and an elastic body of 32 mm in diameter and 2 mm in thickness. A driving voltage of 20 VPP Produces 200 rpm with a torque of 1Nm and an efficiency of about 10%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.19-27
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• 1993

Recent work in the mechanics of fracture points out the desirability of a knowledge of the elastic energy release rate, the crack extension force, and the character of the stress field surrounding a crack tip in analyzing the strength of cracked bodies. The objective of this work is to provide a discussion of the energy rates, stress fields and the like of various cases for anisotropic elastic bodies which might be of interest. Reinforced concrete, wood, laminates, and some special types of elastic bodies with controlled grain orientation are often orthotropic. In this paper, determination of the stress intensity factors(SIFs) of orthotropic plane elastic body using crack tip singular element and fine mesh in near the crack tip is performed. A numerical method in this paper was used by displacement correlation method. A numerical example problem of an orthotropic cantilevered single edge cracked elastic body subjected to shear loading was analyzed, and the results of this paper are in good agreement with those of the others.

• Coupled systems mechanics
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• v.2 no.3
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• pp.271-288
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• 2013

In the present study an elastic-plastic strain analysis is carried out for fibrous composites by using numerical modeling. Application of homogeneous transversely-isotropic model was chosen based on problem solution of a square plate with a circular hole under uniaxial tension. The results obtained in this study correspond to the solution of fiber model trial problem, as well as to analytical solution. Further, numerical algorithm and software has been developed, based on simplified theory of small elastic strains for transversely-isotropic bodies, and FEM. The influence of holes and cracks on stress state of complicated configuration transversely-isotropic bodies has been studied. Strain curves and plasticity zones that are formed in vicinity of the concentrators has been provided. Numerical values of effective mechanical parameters calculated for unidirectional composites at different ratios of fiber volume content and matrix. Content volume proportions of fibers and matrix defined for fibrous composite material that enables to behave as elastic-plastic body or as a brittle material. The influences of the fibrous structure on stress concentration in vicinity of holes on boron/aluminum D16, used as an example.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.107-116
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• 1993

In the design and operation of robitic arm with flexible links, the equation of motion are required to exactly model the interaction between rigid body motion and elastic motion and to be formulated efficientlyl. In this paper, the flexible link is represented by applying the D-H rigid link representation method to measure the elestic deformation. And the equations of motion of robotic arm, which are configured by the generalized coordinates of elastic and rigid degrees of freedom, are formulated from the principle of virtual power. Dynamic characteristics due to elastic deformation of each link are obtained by using F. E. M to model complex shaped link acurately and by eliminating elastic modes of higher order that do not largely affect motion to reduce the number of elastic degrees of freedom. Also presented is the result of simulation of flexible robotic arms whose joints are controlled by direct or PD control.

• Journal of Fashion Business
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• v.21 no.2
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• pp.78-90
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• 2017

In this study, brassiere prototype was developed for attaching the measuring module of ECG measurement and body movement while sleeping. For ECG measurement, textile electrodes was made of stretch fabric containing polyurethane in consideration of elasticity of brassiere band. It was used as a conductive yarn by silver coating on the warp. The textile electrodes was woven with twisted twill to increase the density of conductive yarns. The pressure of the brassiere band was enough to sensing stably the ECG, and the elastic band of the brassiere was designed to be wider than 3cm to install the textile electrodes inside, so that textile electrodes was close fitting to the skin at a constant pressure without lifting. The textile electrodes coated with silicon on rear was attached to brassiere elastic band, and the module was installed with a snap connector to textile electrodes of brassiere band. The module was suitable to monitering ECG measurement of a typical R peak, pulse rate and body movement while sleeping without interfering.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.4
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• pp.54-63
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• 2002

In recent years, mechanical systems such as high speed vehicles and railway trains moving on elastic beam structures have become a very important issue to consider. In this paper, a general approach, which can predict the dynamic behavior of a constrained mechanical system moving on a flexible beam structure, is proposed. Various supporting conditions for the foundation support are considered for the elastic beam structure. The elastic structure is assumed to be a non-uniform and linear Bernoulli-Euler beam with a proportional damping effect. Combined differential-algebraic equation of motion is derived using the multi-body dynamics theory and the finite element method. The proposed equations of motion can be solved numerically using the generalized coordinate partitioning method and predictor-corrector algorithm, which is an implicit multi-step integration method.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.214-220
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• 2010

This article described that a high Reynolds number version of a turbulence model was modified by using drag reduction to analyze the turbulent flows of non-Newtonian fluid with visco-elastic viscosity and it was applied hemodynamics which was representative of visco-elastic fluid. The turbulence characteristics of visco-elastic fluid was expanded viscous sublayer region and buffer layer region by drag reduction phenomenon and also Newtonian turbulence models does not predict because viscosity was related with shear rate of fluid flow. Hence numerical simulation using a modified turbulence model was conducted under the same conditions that were applied to obtain the experiment results and previous turbulence models and then the numerical investigation of turbulent blood flow in the stenosed artery bifurcation under periodic acceleration of the human body.