• International Journal of Highway Engineering
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• v.18 no.6
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• pp.131-136
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• 2016

OBJECTIVES : The objective of this research is to determine the integrity of pavement structures for areas where voids exist. Furthermore, we conducted the study of voided-area analysis and remaining life prediction for pavement structures using finite element method. METHODS : To determine the remaining life of the existing voided areas under asphalt concrete pavements, field and falling weight deflectometer (FWD) tests were conducted. Comparison methods were used to have better accuracy in the finite element method (FEM) analysis compared to the measured surface displacements due to the loaded trucks. In addition, the modeled FEM used in this study was compared with well-known software programs. RESULTS : The results show that a good agreement on the analyzed and measured displacements can be obtained through comparisons of the surface displacement due to loaded trucks. Furthermore, the modeled FEM program was compared with the available pavement-structure software programs, resulting in the same values of tensile strains in terms of the thickness of asphalt concrete layers. CONCLUSIONS : The study, which is related to voided-area analysis and remaining life prediction using FEM for pavement structures, was successfully conducted based on the comparison between our methods and the sinkhole grade used in Japan.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.291-296
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• 2007

To analyze accurately the free vibration of a structure by using the finite element method (FEM), we model the structure as a numerical model with many degrees-of-freedom. However the FEM needs much computation time and storage in this case. The authors developed the finite element-transfer stiffness coefficient method (FE-TSCM) for overcoming the drawback of the FEM. In this paper, the authors apply the FE-TSCM to the in-plane free vibration analysis of plates with various shapes. Two numerical examples, a rectangular plate and a triangular plate, are used to compare the results of the FE-TSCM and the FEM. Through the numerical calculation, we confirm that the FE-TSCM can be applied to the plates with various shapes and is effective to in-plane free vibration analysis of plates.

• Journal of Magnetics
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• v.15 no.3
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• pp.138-142
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• 2010

This paper reports the development of an analysis method in a synchronous reluctance motor (SynRM) using the finite element method (FEM) coupled with the electromagnetic field of the Preisach model, which represents an additional thermal source due to hysteresis loss and a thermal field. This study focused on thermal analysis relative to hysteresis and copper losses in a SynRM.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1815-1820
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• 2009

The FEM(Finite Element Method) is widely adopted numerical technique for finding approximate solutions of various engineering problems in which partial differential equations (PDEs) are involved. Although the original purpose of the FEM is focused on numerical analysis itself due to its heavy computation time, this method has been adopted into control engineering field during the last decade to improve product or system performance. In this paper, this trend is briefly introduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.10
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• pp.1009-1016
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• 2007

Finite element alternating method has been suggested and used effectively to obtain the fracture parameters in assessing the integrity of cracked structures. The method obtains the solution from alternating independently between the FEM solution for an uncracked body and the crack solution in an infinite body. In the paper, the finite element alternating method is extended in order to obtain the elastic-plastic stress fields of a three dimensional inner crack. The three dimensional crack solutions for an infinite body were obtained using symmetric Galerkin boundary element method. As an example of a three dimensional inner crack, a penny-shaped crack in a finite body was analyzed and the obtained elastc-plastic stress fields were compared with the solution obtained from the finite element analysis with fine mesh. It is noted that in the region ahead of the crack front the stress values from FEAM are close to the values from FEM. But large discrepancy between two values is observed near the crack surfaces.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.805-815
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• 2003

In order to execute efficiently the free vibration analysis of 2-dimensional structures like plate structures, the author developed the finite element-transfer stiffness coefficient method. This method is based on the combination of the modeling techniques in the FEM and the transfer technique of the stiffness coefficient in the transfer stiffness coefficient method. Numerical results of the simply supported and the elastic supported rectangular plates showed that the present method can be successfully applied to the free vibration analysis of plate structures on a personal computer. We confirmed that, in the case of analyzing the free vibration of rectangular plate structures, the present method is superior to the FEM from the viewpoint of computation time and storage.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.353-361
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• 2022

Linear Elastic Fracture Mechanics (LEFM) has been developed by applying stress analysis to determine the stress intensity factor (SIF, K). The finite element method (FEM) is widely used as a standard tool for evaluating the SIF for various crack configurations. The prediction accuracy can be achieved by applying an adaptive Delaunay triangulation combined with a FEM. The solution can be solved using either direct or iterative solvers. This work adopts the element-by-element preconditioned conjugate gradient (EBE-PCG) iterative solver into an adaptive FEM to solve the solution to heal problem size constraints that exist when direct solution techniques are applied. It can avoid the formation of a global stiffness matrix of a finite element model. Several numerical experiments reveal that the present method is simple, fast, and efficient compared to conventional sparse direct solvers. The optimum convergence criterion for two-dimensional LEFM analysis is studied. In this paper, four sample problems of a two-edge cracked plate, a center cracked plate, a single-edge cracked plate, and a compact tension specimen is used to evaluate the accuracy of the prediction of the SIF values. Finally, the efficiency of the present iterative solver is summarized by comparing the computational time for all cases.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.730-735
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• 2007

This study is a comparison of the results of the orthropic material analysis at cantilever beam model using boundary element(BEM) method and finite element method(FEM). The program with the orthotropic material analysis was developed and applied to the examples in order to evaluate the accuracy of the programs. The examples shows that the results of the BEM is a good agreement with the ABAQUS results.

• Interaction and multiscale mechanics
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• v.6 no.2
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• pp.237-255
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• 2013

In this paper, a meshfree-enriched finite element method (ME-FEM) is introduced for the large deformation analysis of nonlinear path-dependent problems involving contact. In linear ME-FEM, the element formulation is established by introducing a meshfree convex approximation into the linear triangular element in 2D and linear tetrahedron element in 3D along with an enriched meshfree node. In nonlinear formulation, the area-weighted smoothing scheme for deformation gradient is then developed in conjunction with the meshfree-enriched element interpolation functions to yield a discrete divergence-free property at the integration points, which is essential to enhance the stress calculation in the stage of plastic deformation. A modified variational formulation using the smoothed deformation gradient is developed for path-dependent material analysis. In the industrial metal forming problems, the mortar contact algorithm is implemented in the explicit formulation. Since the meshfree-enriched element shape functions are constructed using the meshfree convex approximation, they pose the desired Kronecker-delta property at the element edge thus requires no special treatments in the enforcement of essential boundary condition as well as the contact conditions. As a result, this approach can be easily incorporated into a conventional displacement-based finite element code. Two elasto-plastic problems are studied and the numerical results indicated that ME-FEM is capable of delivering a volumetric locking-free and pressure oscillation-free solutions for the large deformation problems in metal forming analysis.

• Korean Journal of Agricultural Science
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• v.30 no.2
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• pp.184-190
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• 2003

Finite element method(FEM) was used to obtain an approximate solution, since the mathematical formulations for the problem are complex and cannot be solved analytically. In this study, the fruit as well as the aluminum support on vibrator are discretized into small elements, and the approximate functions are used to describe the displacements in each element in terms of nodal values, and because of the complexity of the problem of viscoelastic materials such as the fruit and vegetables, it was necessary to validate the modeling approach before pear simulations were performed, and the finite element modeling approach was first validated by comparing the results obtained from simulation and experiment for the pear in the frequency range 3 to 150 Hz and acceleration level of 0.25 G-rms. Based on the relatively good agreement between simulated and measured frequencies for the pear, finite element models of tomato and oriental melon were created to study the vibration characteristics of the fruit and vegetables. The resonance frequencies of the pear, tomato and oriental melon using FEM were 62.50, 39.45 and 62.73 Hz and the peak accelerations of them using FEM were 2.21, 1.38 and 1.98 G-rms.