• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.451-456
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• 2007

A finite element analysis and experiment study of a motorcycle helmet are presented in this paper. The finite element LS-DYNA3D code is used to analyze the helmet. The test specimen, instruments, and setup procedures are described. Since the displacements and Von-Mises stresses obtained by numerical analysis and experiment agree well, the numerical simulation is proved to be valid.

• Structural Engineering and Mechanics
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• v.18 no.1
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• pp.59-78
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• 2004

This paper is devoted to illustrate some numerical procedures to solve the boundary equilibrium problems of three-dimensional solids that are subjected to thermal strains. The constitutive equations take into account the bounded tensile strength of the material and they are presented in the framework of non-linear elasticity and small strains. The associated equilibrium problem is solved numerically by means of the finite element method and the numerical techniques, i.e. the Newton-Raphson method and the secant method, are revised in order to assure the solution convergence of the discretized problem. Some numerical examples are illustrated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.607-613
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• 2010

FRANC3D is a program for simulating arbitrary three-dimensional crack growth. Recently, a completely new version of the program, FRANC3D/NG, has been created. Unlike previous versions, which relied largely on boundary element analysis, the new version of the program works with finite element analysis exclusively and is designed to work with general-purpose commercial finite element packages. This paper presents the theoretical underpinnings of the procedures to adaptively modify the geometry and mesh of a model to simulate crack growth.

• Geomechanics and Engineering
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• v.5 no.2
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• pp.165-185
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• 2013

In the present study, the numerical and experimental investigations were performed on the backfill- exterior wall-fluid interaction systems in case of empty and full tanks. For this, firstly, the non-linear three dimensional (3D) finite element models were developed considering both backfill-wall and fluid-wall interactions, and modal analyses for these systems were carried out in order to acquire modal frequencies and mode shapes by means of ANSYS finite element structural analysis program. Secondly, a series of field tests were fulfilled to define their modal characteristics and to compare the results from proposed approximation in the selected structures. Finally, comparing the theoretical predictions from the finite element models to results from experimental measurements, a close agreement was found between theory and experiment. Thus, it can be easily stated that experimental verifications provide strong support for the finite element models and the proposed procedures themselves are the meritorious approximations to the real problem, and this makes the models appealing for use in further investigations.

• Steel and Composite Structures
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• v.15 no.3
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• pp.281-298
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• 2013

Composite special moment frame is one of the systems that are utilized in areas with low to high seismicity to deal with earthquake forces. Composite moment frames are composed of reinforced concrete columns (RC) and steel beams (S); therefore, the connection region is a combination of steel and concrete materials. In current study, a three dimensional finite element model of composite connections is developed. These connections are used in special composite moment frame, between reinforced concrete columns and steel beams (RCS). Finite element model is discussed as a most reliable and low cost method versus experimental procedures. Based on a tested connection model by Cheng and Chen (2005), the finite element model has been developed under cyclic loading and is verified with experimental results. A good agreement between finite element model and experimental results was observed. The connection configuration contains Face Bearing Plates (FBPs), Steel Band Plates (SBPs) enveloping around the RC column just above and below the steel beam. Longitudinal column bars pass through the connection with square ties around them. The finite element model represented a stable response up to the first cycles equal to 4.0% drift, with moderately pinched hysteresis loops and then showed a significant buckling in upper flange of beam, as the in test model.

• Journal of Korean Association for Spatial Structures
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• v.3 no.2 s.8
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• pp.85-90
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• 2003

If we use a third order approximation for the displacement function of beam element in finite element methods, finite element solutions of beams yield nodal displacement values matching to beam theory results to have no connection with the number increasing of elements of beams. It is assumed that, as the member displacement value at beam nodes are correct, the calculation procedure of beam element stiffness matrix have no numerical errors. A the member forces are calculated by the equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$, the member forces at nodes of beams have errors in a moment and a shear magnitudes in the case of smaller number of element. The nodal displacement value of plate subject to the lateral load converge to the exact values according to the increase of the number of the element. So it is assumed that the procedures of plate element stiffness matrix calculations has a error in the fundamental assumptions. The beam methods for the high accuracy ratio solution Is also applied to the plate analysis. The method of reducing a error ratio of member forces and element stiffness matrix in the finite element methods is studied. Results of study were as follows. 1. The matrixes of EI[B] and [K] in the equations of M(x)=EI[B]{q} and M(x) = [K]{q}+{Q} of beams are same. 2. The equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$ for the member forces have a error ratio in a finite element method of uniformly loaded structures, so equilibrium node loads {Q} must be substituted in the equation of member forces as the numerical examples of this paper revealed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.568-576
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• 2005

A 3-D finite element model combined with a volume tracking method is presented in this work to simulate the mold filling for casting processes. Especially, the analysis involves an adaptive grid method that is created under a criterion of element categorization of filling states and locations in the total region at each time step. By using an adaptive grid wherein the elements, finer than those in internal and external regions, are distributed at the surface region through refinement and coarsening procedures, a more efficient analysis of transient fluid flow with free surface is achieved. Adaptive grid based on VOF method is developed in tetrahedral element system. Through a 3-D analysis of the benchmark test of the casting process, the efficiency of the proposed adaptive grid method is verified. Developed FE code is applied to a typical industrial part of the casting process such as aluminum road wheel.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1222-1229
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• 1993

An advanced design environment , which is based on adaptive and knowledge -based finite elements (INTELMESH), has been developed. Unlike other approaches, INTEMMESH incorporates the information about the object geometry as well as the boundary and loading conditions to generate an ${\alpha}$-priori finite element mesh which is more refined around the critical regions of the problem domain. INTEMMESH is designed for planar domains and axisymmetric 3-D structures of elasticity and heat transfer subjected to mechanical and thermal loading . It intelligently identifies the critical regions/points in the problem domain and utilize the new concepts of substructuring and wave propagation to choose the proper mesh size for them. INTEMMESH generates well-shaped triangular elements by applying trangulartion and Laplacian smoothing procedures. The adaptive analysis involves the intial finite elements analyze and an efficient ${\alpha}$-posteriori error analysis involves the initial finite element anal sis and an efficient ${\alpha}$-posteriori error analysis and estimation . Once a problem is defined , the system automatically builds a finite element model and analyzes the problem though automatic iterative process until the error reaches a desired level. It has been shown that the proposed approach which initiates the process with an ${\alpha}$-priori, and near optimum mesh of the object , converges to the desired accuracy in less time and at less cost. Such an advanced design/analysis environment will provide the capability for rapid product development and reducing the design cycle time and cost.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.37-42
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• 1990

In order to obtain optimal design criteria and operating parameters, a Single-sided Linear Induction Motor (SLIM) is analysed by using a 2-D finite element method with magnetic and current vector potential. In the analysing procedures, the governing equation is derived from Maxwell's equation combined with the magnetic vector potential. As a forcing term, 3-phase voltage source is employed using the Kirchhoff's voltage law in order to look into effects of the unbalanced 3-phase currents and air gap flux density. Also, 2ndary eddy current distribution, longitudinal end and transverse edge effects are in turns visualized by flux lines in 3 different analysing planes as functions of frequency and input power.

• Structural Engineering and Mechanics
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• v.22 no.1
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• pp.53-70
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• 2006

The paper summarizes the dynamic-based assessment of a reinforced concrete arch bridge, dating back to the 50's. The outlined approach is based on ambient vibration testing, output-only modal identification and updating of the uncertain structural parameters of a finite element model. The Peak Picking and the Enhanced Frequency Domain Decomposition techniques were used to extract the modal parameters from ambient vibration data and a very good agreement in both identified frequencies and mode shapes has been found between the two techniques. In the theoretical study, vibration modes were determined using a 3D Finite Element model of the bridge and the information obtained from the field tests combined with a classic system identification technique provided a linear elastic updated model, accurately fitting the modal parameters of the bridge in its present condition. Hence, the use of output-only modal identification techniques and updating procedures provided a model that could be used to evaluate the overall safety of the tested bridge under the service loads.