• Journal of the Institute of Convergence Signal Processing
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• v.4 no.4
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• pp.40-46
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• 2003

In this research, we accomplished the interpreting about the vibration of the object, which is the out of plane displacement in the Electronic Speckle Pattern Interferometry(ESPI), one of the optical measuring technique. The vibrating object has a inherent nodal line, therefore we can get the information about the vibration of the object by interpreting it. we used a speaker and a cantilever plate for a measurement object, and interpreted it qualitatively by using the Time-Average ESPI. In this experimental result, the speaker has the lower mode of fringe at 550Hz, 570mV, and the higher mode of fringe at 950Hz, 570mV This ESPI is a non-destructive test, and because of using the laser at measuring, it has a high resolution. The ESPI can test vibration mode regardless of the test object size, because the area which illuminated laser is the test area.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1900-1907
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• 1992

This paper presents the vibration mode, natural frequencies and amplitudes of the circular plate due to the changes of the boundary conditions by varying free arc angles. The vibration mode, amplitudes and natural frequencies of the circular plate are obtained by time-average holographic interferometry and laser doppler vibrometer. The vibration modes of the circular plate with the mixed boundary conditions are found from the 1st mode to the 4th mode. The curve shapes of the natural frequency ratios obtained from this study are in a good agreement with other results obtained by numerical analysis. The displacement curves obtained from time average holographic interferometry and laser doppler vibrometer agree well in case of large amplitude, but show a little difference in case of small amplitude.

• Computational Structural Engineering
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• v.3 no.3
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• pp.133-140
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• 1990

Analysis of cable structures is complex because their force - displacement relationships are highly nonlinear and also because large deformations introduce geometric nonlinearity. Therefore, we must take account their geometric nonlinearity in the analysis and find the equilibrated shape of cable structures. In this paper, to slove these problems, numerical procedures involving geometrical nonlinearity are introduced. They are applicable to general cable net, flexible transmission lines and suspended cable roof. These procedures are divided into two parts; one is to obtain the equilibrated shapes and stresses of the cable structures with uniform load by flexibility iteration method, the other is to analyse the equilibrated structures subjected to nodal external forces by nonlinear finite element method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2505-2510
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• 2013

Parametric studies on nonhomogeneous pile and homogeneous pile installed in clay were performed through the developed technique to investigate the effects of considered factors on the lateral pile behaviors. Values of the parameters with embedment depths of the two piles having different flexural rigidity show that values of the parameters for more rigid pile were greater than those for smaller one. Parameters for the case of the nonhomogeneous pile were converged to the same ones of the homogeneous pile as nodal point moves away from point of material boundary. In order to determine adequate upper length of the nonhomogeneous pile, changing patterns of the parameters, lateral displacement, member forces and so forth should be compared.

• Ocean Systems Engineering
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• v.1 no.4
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• pp.337-353
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• 2011

In the present study, an offshore platform having large partial porous cylindrical members, which are composed of permeable and impermeable cylinders, is suggested. In order to calculate the wave force on large partial porous cylindrical members, the fluid domain is divided into three regions: a single exterior region, N inner regions and N beneath regions, and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. Applying Darcy's law to the porous boundary condition, the effect of porosity is simplified. Wave excitation forces and wave run up on the structures are presented for various wave conditions. For the idealized three-dimensional platform having large partial porous cylindrical members, the dynamic response evaluations of the platform due to wave forces are carried out through the modal analysis. In order to examine the effects of soil-structure interaction, the substructure method is also applied. The displacement and bending stress at the selective nodal points of the structure are computed using various input parameters, such as the shear-wave velocity of soil, the wave height and the wave period. Applying the Monte Carlo Simulation (MCS) method, the reliability evaluations at critical structure members, which contained uncertainties caused by dynamic forces and structural properties, are examined by the reliability index with the results obtained from MCS.

• Steel and Composite Structures
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• v.22 no.2
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• pp.301-321
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• 2016

The objective of this paper is to investigate buckling behavior of composite laminated cylinders by using semi-analytical finite strip method. The shell is subjected to deformation-dependent loads which remain normal to the shell middle surface throughout the deformation process. The load stiffness matrix, which is responsible for variation of load direction, is also throughout the deformation process. The shell is divided into several closed strips with alignment of their nodal lines in the circumferential direction. The governing equations are derived based on the first-order shear deformation theory with Sanders-type of kinematic nonlinearity. Displacements and rotations of the shell middle surface are approximated by combining polynomial functions in the meridional direction and truncated Fourier series along with an appropriate number of harmonic terms in the circumferential direction. The load stiffness matrix, which is responsible for variation of load direction, is also derived for each strip and after assembling, global load stiffness matrix of the shell is formed. The numerical illustrations concern the pressure stiffness effect on buckling pressure under various conditions. The results indicate that considering pressure stiffness causes buckling pressure reduction which in turn depends on various parameters such as geometry and lay-ups of the shell.

• Structural Engineering and Mechanics
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• v.67 no.4
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• pp.317-326
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• 2018

The iterative decomposition coupling formulation of the precise integration finite element method (FEM) and the time domain boundary element method (TD-BEM) is presented for elstodynamic problems. In the formulation, the FEM node and the BEM node are not required to be coincident on the common interface between FEM and BEM sub-domains, therefore, the FEM and BEM are independently discretized. The force and displacement converting matrices are used to transfer data between FEM and BEM nodes on the common interface between the FEM and BEM sub-domains, to renew the nodal variables in the process of the iterations for the un-coincident FEM node and BEM node. The iterative coupling formulation for elastodynamics in current paper is of high modeling accuracy, due to the semi-analytical solution incorporated in the precise integration finite element method. The decomposition coupling formulation for elastodynamics is verified by examples of a cantilever bar under a Heaviside-type force and a harmonic load.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.51-57
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• 2015

Various hybrid dampers have been developed in Korea to control the vibration due to a wind and earthquake. In order to minimize the installment space, cost and construction process, the new hybrid friction damper is developed. This hybrid damper is composed of several rotary friction components having two frictional joint. Because of these components, the building vibration due to wind and earthquake can be mitigated by hybrid friction damper. In this paper, various dependency tests were carried out to evaluate on the structural performance of two joint rotational friction component of the hybrid damper. Test results show that two joint rotational components do not depend on a displacement and a frequency of forcing but friction coefficients is reducing as a clamping force is increasing.

• Interaction and multiscale mechanics
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• v.2 no.2
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• pp.129-151
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• 2009

This paper presents a meshfree procedure using a convex generalized meshfree (GMF) approximation for the large deformation analysis of particle-reinforced rubber compounds on microscopic level. The convex GMF approximation possesses the weak-Kronecker-delta property that guarantees the continuity of displacement across the material interface in the rubber compounds. The convex approximation also ensures the positive mass in the discrete system and is less sensitive to the meshfree nodal support size and integration order effects. In this study, the convex approximation is generated in the GMF method by choosing the positive and monotonic increasing basis function. In order to impose the periodic boundary condition in the unit cell method for the microscopic analysis, a singular kernel is introduced on the periodic boundary nodes in the construction of GMF approximation. The periodic boundary condition is solved by the transformation method in both explicit and implicit analyses. To simulate the interface de-bonding phenomena in the rubber compound, the cohesive interface element method is employed in corporation with meshfree method in this study. Several numerical examples are presented to demonstrate the effectiveness of the proposed numerical procedure in the large deformation analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.27-37
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• 1993

An efficient method to solve the minimum weight design problem for frame structures subjected to stress and displacement constraints is presented. The different cross-sectional shapes are conside red in order to apply engineering design in which usually required custom fabrication. To increase the efficiency of the optimization process, the structural response quantities(nodal forces, displacements) are linearized with respect to cross-sectional properties or their reciprocal, based on first order Taylor series expansion, while cross-sectional dimensions are considered as design variables. Numerical examples are performed and compared with other methods to demonstrate the efficiency and reliability of approximation method for frame structural optimization with different cross-sectional shapes. It is shown that the number of finite element analysis is greatly reduced and it leads to a highly efficient method of optimization of frame structures.