• 대한기계학회논문집A
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• 제20권7호
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• pp.2067-2077
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• 1996

In adaptive finite element analysis, r- and h-methods are generally used on the basis of a discretization error estimator. In this paper, an rh-method is proposed as a new adaptive method which can improve the adaptivity performance by using both of them. This suggested rh-method moves nodal coordinates of initially given model to adjust element discretization errors and thereafter performes the h-method tdo obtain the specified accuracy of finite element solutions. Numerical experiments for various plane problems were performed using 4-noded isoparametric quadrilateral elements. As a result, the rh-method has been shown to be an accurate and efficient adaptive analysis method to obtain as improved solution.

• 한국지진공학회논문집
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• 제23권1호
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• pp.83-88
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• 2019

Structural analysis remains as an essential part of any integrated civil engineering system in today's rapidly changing computing environment. Even with enormous advancements in capabilities of computers and mobile tools, enhancing computational efficiency of algorithms is necessary to meet the changing demands for quick real time response systems. The finite element method is still the most widely used method of computational structural analysis; a robust, reliable and automated finite element structural analysis module is essential in a modern integrated structural engineering system. To be a part of an automated finite element structural analysis, an efficient adaptive mesh generation scheme based on R-H refinement for the mesh and error estimates from representative strain values at Gauss points is described. A coefficient that depends on the shape of element is used to correct overly distorted elements. Two simple case studies show the validity and computational efficiency. The scheme is appropriate for nonlinear and dynamic problems in earthquake engineering which generally require a huge number of iterative computations.

• Journal of Mechanical Science and Technology
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• 제18권10호
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• pp.1837-1848
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• 2004

Interaction behaviors of high-speed compressible viscous flow and thermal-structural response of structure are presented. The compressible viscous laminar flow behavior based on the Navier-Stokes equations is predicted by using an adaptive cell-centered finite-element method. The energy equation and the quasi-static structural equations for aerodynamically heated structures are solved by applying the Galerkin finite-element method. The finite-element formulation and computational procedure are described. The performance of the combined method is evaluated by solving Mach 4 flow past a flat plate and comparing with the solution from the finite different method. To demonstrate their interaction, the high-speed flow, structural heat transfer, and deformation phenomena are studied by applying the present method to Mach 10 flow past a flat plate.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.403-409
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• 2003

The finite element method is one of the most widely used method of structural analysis that has wide applications in diverse fields of engineering and science. The method has been proven effective and reliable in many practical problems. One of the reasons for the methods' popularity is its ease of use, but still the user has to input the finite element mesh which affects the accuracy of the results. The knowledge required to form an effective mesh for a given problem is somewhat complex and for sometime there has been research effort to automate the generation of the mesh and this is called the adaptive mesh generation scheme. A good adaptive mesh scheme seemed to require an accurate assessment of error and generally this requires some additional computation. This paper looks into the possibility of generating adaptive meshes based on representative strain values in each finite element method. The proposed adaptive scheme does not require additional computations other that looking up the data values already computed as finite element analysis results and simple manipulations of these data. Two plane stress problems, a plate with a hole and a deep beam with a concentrated load at the end are considered to show the progress of the improved generation of adaptive meshes using the scheme.

• 대한기계학회논문집B
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• 제29권5호
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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.

• 한국기계가공학회지
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• 제9권5호
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• pp.50-56
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• 2010

Meshfree methods show many advantages over finite element method(FEM) in the class of problems for which the remeshing process is inevitable when the conventional FEM used, such as propagating crack problems, large deformation and so on. One of the promising applications of meshfree methods is the adaptive refinement for problems having multi-scale nature. In this study, an adaptive node generation procedure is proposed and several numerical examples are also presented to illustrate the efficiency of proposed method.

• 오토저널
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• 제10권6호
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• pp.54-60
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• 1988

During recent years, a great deal of interest has emerged on the use of adaptive approaches and a posteriori estimates in finite element method. The results are intended to be used to improve the quality of finite element solution by changing the location of the nodes within a fixed number of degrees of freedom-so called r method-, and by increasing the order of polynomial approximation with the new degrees of freedom-p method. This paper deals with error analysis that contains the basic theory and method of deriving error estimates and adaptive processes applied to finite element solutions underlying the rpm method that is the combination of r and p method of finite element. It is shown that we can obtain more accurate solution by applying the method to the 2-dimensional heat transfer problem.

• 대한기계학회논문집A
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• 제24권7호
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• pp.1763-1770
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• 2000

A finite element interface system for the design of optimal spot welding locations has been developed. In order to find out the optimal locations of spot welding points, iterative finite element an alyses are necessary, and thus automatic generation of finite element model for the structures with spot welded pointsis required. In this interface system, quadrilateral shell elements are automatically generated for finite element analysis of spot welded structured, which employs a domain decomposition methodand adaptive mesh(h-method).

• 대한조선학회지
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• 제23권2호
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• pp.27-32
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• 1986

This paper describes an application of the adaptive finite element computations to a free surface flow problem in a canal. A-posteriori error estimates for the adaptive finite element computations are based on the dual extremum principles. Previously the dual extremum principles were applied to compute the upper and lower bounds of the added mass of two-dimensional cylinders in a canal[1,2]. However, the present method improves the convergence of the computed results by utilizing the local error estimates and by applying the adaptive meshes in the finite element computations. In a test result using triangular elements it is shown that the numerical error in the adaptive finite elements reduces quadratically compared with that in a uniform mesh subdivision.

• 대한전기학회논문지
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• 제39권9호
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• pp.921-927
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• 1990

This paper presents a mesh refinement scheme for 3-D adaptive finite element method. Firstly, the refinement of triangular meshes based on the bisection of triangles is discussed. And a new method to refine tetrahedral meshes employing the bisection method is presented. In two dimensional cases, it has been noted that all angles in the triangular meshes refined by the bisection method are greater than or equal to half the smallest angle in the original meshes. Through the examples where the newly proposed method is applied to three dimensional cases, it is shown that regarding the solid angles, the method gives nearly the same result as that in the two dimensional case. Accordingly, it can be concluded that the proposed method will be useful in the mesh refinements for 3-D adaptive finite element method.