• 한국정밀공학회지
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• 제23권5호
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• pp.143-148
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• 2006

It is still very difficult to generate a geometry model and finite element model, which has complex and many free surface, even though 3D CAD solutions are applied. Furthermore, in the medical field, which is a big growth area of recent years, there is no drawing. For these reasons, making a geometry model, which is used in finite element analysis, is very difficult. To resolve these problems and satisfy the requests of the need to create a 3D digital file for an object where none had existed before, new technologies are appeared recently. Among the recent technologies, there is a growing interest in the availability of fast, affordable optical range laser scanning. The development of 3D laser scan technology to obtain 3D point cloud data, made it possible to generate 3D model of complex object. To generate CAD and finite element model using point cloud data from 3D scanning, surface reconstruction applications have widely used. In the early stage, these applications have many difficulties, such as data handling, model creation time and so on. Recently developed point-based surface generation applications partly resolve these difficulties. However there are still many problems. In case of large and complex object scanning, generation of CAD and finite element model has a significant amount of working time and effort. Hence, we concerned developing a good direct finite element model generation method using point cloud's location coordinate value to save working time and obtain accurate finite element model.

• 소성∙가공
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• 제21권3호
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• pp.172-178
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• 2012

We performed a shot peening test and used a 2-D finite element model which predicts the compressive residual stress distribution below the material's surface. In this study, the concept of 'impact cycle' is introduced to account for the irregularity in the shot's impact position during testing. The impact cycle was imbedded in the finite element model. In the shot peening test, shot bombarded a type-A Almen strip surface with different impact velocities. To verify the proposed finite element model, we compared the deformed cross sectional shape of the Almen strips with the shapes computed by the proposed finite element model. Good agreement was noted between measurements and the finite element model predictions. With the verified finite element model, a series of finite element simulations was conducted to compute the residual stress distribution below the material's surface and the characteristics of these distributions are discussed.

• 한국구조물진단유지관리공학회 논문집
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• 제4권2호
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• pp.113-129
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• 2000

This study evaluates the behavior and strength of an anchorage zone of the prestressed concrete box girder bridge on the Kyungboo highway railroad using the 2D SUB-3D STM approach and a linear elastic finite element analysis. The 2D SUB-3D STM approach utilizes several two-dimensional sub strut-tie models that represent the compressive and tensile stress flows of each projected plane of the three-dimensional structural concrete in the selection of a three dimensional strut-tie model, evaluation of the effective strengths of the concrete struts, and verification of the geometric compatibility condition and bearing capacity of the critical nodal zones in the selected three-dimensional strut-tie model. The finite element analysis uses an 8-node brick element and the longitudinal prestressing force is considered as the equivalent nodal force. Analysis results show that the 2D SUB-3D STM approach and linear elastic finite element method can be effectively applied to the analysis and design of three-dimensional structural concrete including a prestressed concrete box girder anchorage zone.

• Computers and Concrete
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• 제4권2호
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• pp.135-156
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• 2007

Three 3D nonlinear finite-element models are developed to study the behavior of concrete beams and plates with and without external reinforcement by fibre-reinforced plastic (FRP). All three models are formulated based upon the 3D theory of elasticity. The stress model is modified from the element developed by Ramtekkar, et al. (2002) to incorporate material nonlinearity in the formulation. Both transverse stress and displacement components are used as nodal degrees-of-freedom to ensure the continuity of both stress and displacement components between the elements. The displacement model uses only displacement components as nodal degrees-of-freedom. The transition model has both stress and displacement components as nodal degrees-of-freedom on one surface, and only displacement components as nodal degrees-of-freedom on the opposite surface. The transition model serves as a connector between the stress and the displacement models. The developed models are validated by comparing the results of the analyses with an existing experimental result. Parametric studies of the effects of the externally reinforced FRP on the load capacity of reinforced concrete (RC) beams and concrete plates are performed to demonstrate the practicality and the efficiency of the proposed models.

• 대한조선학회논문집
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• 제44권3호
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• pp.314-322
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• 2007

In general, the vibration and structural analyses have been carried out by using each finite element model separately because of different size of finite element mesh and different focusing area of each analysis. In some cases, however, it is required to perform both global vibration and structural analyses at the same time using a finite element model for global structural analysis, which asks for a special treatment for a vibration analysis. In this study, a technique to perform a global vibration analysis using a finite element model for a global structural analysis has been developed and its effectiveness has been verified by its application to a whole ship.

• Structural Engineering and Mechanics
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• 제40권2호
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• pp.257-277
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• 2011

In this paper the geometrically nonlinear continuum plate finite element model, hitherto not reported in the literature, is developed using the total Lagrange formulation. With the layerwise displacement field of Reddy, nonlinear Green-Lagrange small strain large displacements relations (in the von Karman sense) and linear elastic orthotropic material properties for each lamina, the 3D elasticity equations are reduced to 2D problem and the nonlinear equilibrium integral form is obtained. By performing the linearization on nonlinear integral form and then the discretization on linearized integral form, tangent stiffness matrix is obtained with less manipulation and in more consistent form, compared to the one obtained using laminated element approach. Symmetric tangent stiffness matrixes, together with internal force vector are then utilized in Newton Raphson's method for the numerical solution of nonlinear incremental finite element equilibrium equations. Despite of its complex layer dependent numerical nature, the present model has no shear locking problems, compared to ESL (Equivalent Single Layer) models, or aspect ratio problems, as the 3D finite element may have when analyzing thin plate behavior. The originally coded MATLAB computer program for the finite element solution is used to verify the accuracy of the numerical model, by calculating nonlinear response of plates with different mechanical properties, which are isotropic, orthotropic and anisotropic (cross ply and angle ply), different plate thickness, different boundary conditions and different load direction (unloading/loading). The obtained results are compared with available results from the literature and the linear solutions from the author's previous papers.

• Geomechanics and Engineering
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• 제17권4호
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• pp.317-322
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• 2019

This paper presents the results of parametric analyses to compute the axial capacity of a suction pile using 2D and 3D finite element approaches. The study is intended to simplify the process of analyzing suction piles from 3D to 2D model. The research focuses on obtaining the coefficient to be applied into the 2D model in order to obtain results that are as close as possible to the 3D model. Two 2D models were used in the analysis, namely the plane strain and axisymmetric models. The analyses were performed using two actual offshore soil data of the North and West Java Indonesia. The study reveals that the simplification of model through 2D Finite Element is achievable by applying the appropriate coefficient to the stiffness parameters. The results show that the simplified model of the 2D FEA provides more conservative results (with the difference between 2% to 7%) than the 3D FEA.

• Journal of Magnetics
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• 제11권4호
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• pp.151-155
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• 2006

The electromagnetic engine valve actuator is a key technology to achieve variable valve timing in internal combustion engine and the steel core and clapper of the electromagnetic engine valve actuator are laminated to reduce the eddy current loss. To design and characterize the performance of the electromagnetic engine valve actuator, FE (finite element) analysis is the most effective way, but FE (finite element) 3-D modeling of real lamination needs very fine meshes resulting in countless meshes for modeling and numerous computations. In this paper, the equivalent FE 2-D model of electromagnetic engine valve actuator is introduced and FE analysis is performed using the equivalent FE 2-D model.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.447-457
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• 2009

A general analytical method for computing the joint stiffness from the sectional properties of the members that form the joint is derived using Vlasov's thin-walled beam theory. The analytical model of box T-joint under out-of-plane loading is investigated and validated using shell finite element results and experimental data. The analytical model of the T-joint is implemented in a beam finite element model using a revolute joint element. The out-of-plane displacement computed using the beam-joint model is compared with the corresponding shell element model. The results show close correlation between the beam revolute joint model and shell element model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1081-1084
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• 2002

In this study, we perform 3-D reconstruction of human proximal femur from DICOM files by using voxel mesh algorithm. After 3-D reconstruction, the model converted to Finite Element model which developed for automatically making not only 3-D geometrical model but also FE model from medical image dataset. During this job, trabecular pattern, one of characteristic of human bone can be added to the model by means of giving it's own elastic property calculated from intensity in CT scanned image to the each voxel. And then another model is made from same image dataset which have two material properties - one corresponds to cortical bone, another to trabecular bone. Finally, validity of voxel mesh technique is verified through comparing results of FE analysis, free vibration and stress analysis.