• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.247-253
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• 2003

A novel finite element mesh regeneration method is presented for 3D shape optimization of electromagnetic devices. The method has its theoretical basis in the structural deformation of an elastic body. When the shape of the electromagnetic devices changes during the optimization process, a proper 3D finite element mesh can be easily obtained using the method from the initial mesh. For real engineering problems, the method guarantees a smooth shape with proper mesh quality, and maintains the same mesh topology as the initial mesh. Application of the optimum design of an electromagnetic shielding plate shows the effectiveness of the presented method.

• Journal of Magnetics
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• 제19권2호
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• pp.146-150
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• 2014

The objective of this paper is to provide a comparison between two transverse flux rotary machines (TFRM) with different topologies of stator cores. Depending on how to make stator core with laminated steel sheets, the one topology is 'perpendicular stacking core' and the other is 'separated core'. Both of the two cores have been designed considering 3-dimensional (3-D) magnetic flux path with the same output power conditions, but the core losses are quite different and it causes different magnetic and thermal characteristics. For comparison of these two topologies of stator cores, therefore, core losses have been calculated and used as a heat source in no-load conditions, and the thermal stress has been also calculated. 3-D finite element method has been used for the magnetic field, thermal, and stress analysis to consider the 3-D flux path of the TFRM. After comparing the analysis results of the two topologies, experimental results are also presented and discussed.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.665-676
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• 2018

In this study, a four-node quadrilateral partial mixed plate element with low degrees of freedom (dofs) is developed for static and free vibration analysis of functionally graded material (FGM) plates rested on Winkler-Pasternak elastic foundations. The formulation of the presented finite element model is based on a parametrized mixed variational principle which is developed recently by the first author. The presented finite element model considers the effects of shear deformations and normal flexibility of the FGM plates without using any shear correction factor. It also fulfills the boundary conditions of the transverse shear and normal stresses on the top and bottom surfaces of the plate. Beside these capabilities, the number of unknown field variables of the plate is only six. The presented partial mixed finite element model has been validated through comparison with the results of the three-dimensional (3D) theory of elasticity and the results obtained from the classical and high-order plate theories available in the open literature.

• Steel and Composite Structures
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• 제12권2호
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• pp.93-115
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• 2012

This paper presents a numerical investigation of the mechanical behaviour of extended end - plate steel connections including comparison with full size experiments. Contact and friction laws have been taken into account with nonlinear, three dimensional finite element analysis. Material and geometric nonlinearities have been implemented to the model, as well. Results are then compared with experimental tests conducted at the Jordan University of Science and Technology. According to the most significant observation of the analysis, a separation of the column flange from the extended end - plate occurs. Other important structural parameters of the connection, like the impact of some column stiffeners on the overall response, local buckling of the column and friction of the beam to column interface, have been examined as well.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2947-2950
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• 2007

A 3D human ventricular model is proposed to simulate an integrative analysis of heart physiology and blood hemodynamics. This consists of the models of electrophysiology of human cells, electric wave propagation of tissue, heart solid mechanics, and 3D blood hemodynamics. The 3D geometry of human heart is discretized to a finite element mesh for the simulation of electric wave propagation and mechanics of heart. In cellular level, excitations by action potential are simulated using the existing human model. Then the contraction mechanics of a whole cell is incorporated to the excitation model. The excitation propagation to ventricular cells are transiently computed in the 3D cardiac tissue using a mono-domain method of electric wave propagation in cardiac tissue. Blood hemodynamics in heart is also considered and incorporated with muscle contraction. We use a PISO type finite element method to simulate the blood hemodynmaics in the human ventricular model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.325-327
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• 1998

Disk type single-phase switched reluctance motor which has an advantage of simple robust construction, simple control circuity, and low manufacturing cost has a specific property of axial flux machine and radial flux machine simultaneously. So, this DSPSRM has a complicated magnetic circuit and it is difficult to analyze characteristics of DSPSRM for design. In this paper, we used to analyze the effects of radial flux and axial flux simultaneously by 3D-finite element method. From the results of 3-D FEM, we obtained the approximated torque characteristics of DSPSRM. It's analysis results can be used in optimal design of DSPSRM considering the saturation.

• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.19-29
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• 2000

A viscoelastic finite element analysis is presented to investigate residual stresses occurred in a laminated cylindrical shell during cure. An incremental viscoelastic constitutive equation that can describe stress relaxation during the cure is derived as a recursive formula which can be used conveniently for a numerical analysis. The finite element analysis program is developed on the basis of a 3-D degenerated shell element and the first order shear deformation theory, and is verified by comparing with an one dimensional exact solution. Viscoelastic effect on the residual stresses in the laminated shell during the cure is investigated by performing both the viscoelastic and linear elastic analyses considering thermal deformation and chemical shrinkage simultaneously. The results show that there is big difference between viscoelastic stresses and linear elastic stresses. The effect of cooling rates and cooling paths on the residual stresses is also examined.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.462-465
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• 2004

Since quasi-brittle materials like concrete show strain localization behavior accompanied by strain softening, a numerical drawback such as mesh sensitivity is appeared in the finite element analysis. In this paper, the so-called homogenized crack model which was introduced for three dimensional finite element analysis of fracture in concrete is studied for the mesh size dependence problem in fracture analysis. A homogenized crack element having a velocity discontinuity. is averaged to remove the mesh sensitivity in finite element analysis of concrete fracture. Numerical examples show that softening behavior of concrete fracture is successfully predicted without mesh sensitivity using the homogenized crack model.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 금형가공 심포지엄
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• pp.274-284
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• 2002

Deep drawing process for rectangular drawn section is different with that for axisymmetric circular one. Therefore deep drawing process for rectangular drawn section requires several intermediate steps to generate the final configuration without any significant defect. In this study, finite element analysis for multi-stage deep drawing process for high precision rectangular cases is carried out especially for an extreme aspect ratio. The analysis is performed using rigid-plastic finite element method with an explicit time integration scheme of the commercial program, LS-DYNA3D. The sheet blank is modeled using eight-node continuum brick elements. The results of analysis show that the irregular contact condition between blank and die affects the occurrence of failure, and the difference of aspect ratio in the drawn section leads to non-uniform metal flow, which may cause failure. A series of experiments for multi-stage deep drawing process for the rectangular cases are conducted, and the deformation configuration and the thickness distribution of the drawn rectangular cases are investigated by comparing with the results of the numerical analysis. The numerical analysis with an explicit time integration scheme shows good agreement with the experimental observation.

• 대한산업공학회지
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• 제23권1호
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• pp.215-222
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• 1997

This paper deals with the problem of generating a uniform tetrahedral mesh which fills a 3-D space with the tetrahedra which are close to the equilateral tetrahedra as possible. This problem is particularly interesting in finite element modeling where a fat triangulation minimizes the error of an analysis. Fat triangulation is defined as a scheme for generating an equilateral triangulation as possible in a given dimension. In finite element modeling, there are many algorithms for generating a mesh in 2-D and 3-D. One of the difficulties in generating a mesh in 3-D is that a 3-D object can not be filled with uniform equilateral tetrahedra only regardless of the shape of the boundary. Fat triangulation in 3-D has been proved to be the one which fills a 3-D space with the tetrahedra which are close to the equilateral as possible. Topological and geometrical properties of the fat triangulation and its application to meshing algorithm are investigated.