• Title/Summary/Keyword: numerical differentiation

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Application of Numerical Differentiation in Structural Analysis (구조해석에서 수치미분의 적용)

  • 김영일;신성철;이태은;이병구
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2001.10a
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    • pp.53-58
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    • 2001
  • This paper deals with the application of numerical differentiation in the structural analysis. In the structural analysis, the derivative values of the given function are sometimes used in calculation of structural behaviors. For calculating the derivative values, both the time and labor are needed when the structures consist of non-linear geometries such as arches or curved beams. From this viewpoint the numerical differentiation scheme is applied into the structural analysis. The numerical results obtained from the numerical differentiation are agreed very well with those obtained from the exact derivatives by analytical method. It is expected that the numerical differentiation can be utilized practically in the structural analysis.

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STABLE NUMERICAL DIFFERENTIATION: WHEN IS IT POSSIBLE?

  • Ramm, Alexander G.;Smirnova, Alexandra
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.7 no.1
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    • pp.47-61
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    • 2003
  • Two principally different statements of the problem of stable numerical differentiation are considered. It is analyzed when it is possible in principle to get a stable approximation to the derivative ${\Large f}'$ given noisy data ${\Large f}_{\delta}$. Computational aspects of the problem are discussed and illustrated by examples. These examples show the practical value of the new understanding of the problem of stable differentiation.

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A Study on the Convergency of the Finite Element Analysis of Rubber Using Numerical Differentiation Mehthod (수치미분을 이용한 고무의 유한요소 해석시 수렴성 연구)

  • 권영두;노권택;이창섭;홍상표
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.5
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    • pp.141-153
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    • 1999
  • A finite element procedure for the analysis of rubber-like hyperelastic material is developed. The volumetric incompressiblity conditions of the rubber deformation is included in the formulation by using penalty method. In this paper, the behavior of the rubber deformation is represented by hyperelastic constitutive relations based on a generalized Mooney-Rivlin model. The principle of virtual work is used to derive nonlinear finite element equation for the large displacement problem and presented in total-Lagrangian description. The finite element procedure using analytic differentiation resulted in very close solution to the result of the well known commercial packages NISAII AND ABAQUS. Numerical tests show that the results from the numerical differentiation method coincide very well with those from the analytic method and the well known commercial packages in static analysis. The convergency of rubber usingν iteration method is also discussed.

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Application of Numerical Differentiations in Free Vibration Analysis (자유진동 해석에서 수치미분의 응용)

  • 이병구;안대순;강희종;김권식
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.814-818
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    • 2003
  • This paper deals with the application of numerical differentiation in free vibration analysis. In the free vibration analysis, the derivative values of the given function are certainly used in calculation of structural parameters. For deriving the derivative values, both the time and labor are needed when the structures consist of non-linear geometries such as arches or curved beams. From this viewpoint, the numerical differentiation scheme is applied into the free vibration analysis. The numerical results obtained from the numerical differentiations are agreed very well with those obtained from the exact derivatives by analytical method. It is expected that the numerical differentiations can be utilized practically in the free vibration analysis.

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ON A SIMPLE HIGH ORDER NUMERICAL DIFFERENTIATION USING THE LAGRANGE INTERPOLATION

  • HAHM N.;YANG M.;HONG B. I.
    • Journal of applied mathematics & informatics
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    • v.19 no.1_2
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    • pp.527-535
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    • 2005
  • Numerical differentiation is one of the main topics which have been studied by many researchers. If we use the forward difference scheme or the centered difference scheme, the convergence rates to the derivative are O(h) and O($h^2$), respectively. In this paper, using the Lagrange Interpolation, we construct a simple high order numerical differentiation scheme which has the convergence rate O($h^{2k}$) if we have 2k+1 equally spaced nodes. Our scheme is constructive.

Application of Numerical Differentiation in Structural Analyses of Arch Structures (아치구조물의 구조해석에서 수치미분의 적용)

  • Lee, Byoung-Koo;Kim, Suk-Ki;Lee, Tae-Eun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.4 s.74
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    • pp.441-447
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    • 2006
  • This paper deals with the application of the numerical differentiation in the structural analyses. Derivative values of the geometry of structure are definitely needed for analysing the structural behavior. In this study, free vibration problems of arches are chosen for verifying the numerical differential technique in the structural analyses. The curvature parameters composed with the derivatives of arch geometry obtained herein are quite agreed with those of analytical method. Also, natural frequencies with curvature parameters obtained by using the forward fifth polynomial method are quite agreed with those in the literature. The numerical differentiation technique can be practically utilized in the structural analyses.

Improved Concurrent Subspace Optimization Using Automatic Differentiation (자동미분을 이용한 분리시스템동시최적화기법의 개선)

  • 이종수;박창규
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.10a
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    • pp.359-369
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    • 1999
  • The paper describes the study of concurrent subspace optimization(CSSO) for coupled multidisciplinary design optimization (MDO) techniques in mechanical systems. This method is a solution to large scale coupled multidisciplinary system, wherein the original problem is decomposed into a set of smaller, more tractable subproblems. Key elements in CSSO are consisted of global sensitivity equation(GSE), subspace optimization (SSO), optimum sensitivity analysis(OSA), and coordination optimization problem(COP) so as to inquiry valanced design solutions finally, Automatic differentiation has an ability to provide a robust sensitivity solution, and have shown the numerical numerical effectiveness over finite difference schemes wherein the perturbed step size in design variable is required. The present paper will develop the automatic differentiation based concurrent subspace optimization(AD-CSSO) in MDO. An automatic differentiation tool in FORTRAN(ADIFOR) will be employed to evaluate sensitivities. The use of exact function derivatives in GSE, OSA and COP makes Possible to enhance the numerical accuracy during the iterative design process. The paper discusses how much influence on final optimal design compared with traditional all-in-one approach, finite difference based CSSO and AD-CSSO applying coupled design variables.

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DISCRETE TORSION AND NUMERICAL DIFFERENTIATION OF BINORMAL VECTOR FIELD OF A SPACE CURVE

  • Jeon, Myung-Jin
    • The Pure and Applied Mathematics
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    • v.12 no.4 s.30
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    • pp.275-287
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    • 2005
  • Geometric invariants are basic tools for geometric processing and computer vision. In this paper, we give a linear approximation for the differentiation of the binormal vector field of a space curve by using the forward and backward differences of discrete binormal vectors. Two kind of discrete torsion, say, back-ward torsion $T_b$ and forward torsion $T_f$ can be defined by the dot product of the (backward and forward) discrete differentiation of binormal vectors that are linear approximations of torsion. Using Frenet formula and Taylor series expansion, we give error estimations for the discrete torsions. We also give numerical tests for a curve. Notably the average of $T_b$ and $T_f$ looks more stable in errors.

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Augmented Displacement Load Method for Nonlinear Semi-analytical Design Sensitivity Analysis (준해석적 비선형 설계민감도를 위한 개선된 변위하중법)

  • Lee, Min-Uk;Yoo, Jung-Hun;Lee, Tae-Hee
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.492-497
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    • 2004
  • Three methods for design sensitivity such as numerical differentiation, analytical method and semi-analytical method have been developed for the last three decades. Although analytical design sensitivity analysis is exact, it is hard to implement for practical design problems. Therefore, numerical method such as finite difference method is widely used to simply obtain the design sensitivity in most cases. The numerical differentiation is sufficiently accurate and reliable for most linear problems. However, it turns out that the numerical differentiation is inefficient and inaccurate because its computational cost depends on the number of design variables and large numerical errors can be included especially in nonlinear design sensitivity analysis. Thus semi-analytical method is more suitable for complicated design problems. Moreover semi-analytical method is easy to be performed in design procedure, which can be coupled with an analysis solver such as commercial finite element package. In this paper, implementation procedure for the semi-analytical design sensitivity analysis outside of the commercial finite element package is studied and computational technique is proposed, which evaluates the pseudo-load for design sensitivity analysis easily by using the design variation of corresponding internal nodal forces. Errors in semi-analytical design sensitivity analysis are examined and numerical examples are illustrated to confirm the reduction of numerical error considerably.

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Application of Numerical Differentiation Using Differential Quadrature (DQ) to Curved Member-like Structural Analysis (곡선부재의 구조해석에서 미분구적(DQ)을 이용한 수치미분의 적용)

  • Lee, Byoung-Koo;Oh, Sang-Jin;Lee, Tae-Eun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.2 s.119
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    • pp.185-193
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    • 2007
  • This paper deals with the application of the numerical differentiation using the differential quadrature(DQ) in the curved member-like structural analysis. Derivative values of the geometry of structure are definitely needed for analyzing the structural behavior. For verifying the numerical differentiation using DQ, free vibration problems of arch are selected. Terms of curvature composed with the derivatives of arch geometry obtained herein are agreed quite well with exact values obtained explicitly. Natural frequencies subjected to terms of curvature obtained by DQ are agreed quite well with those in the literature. The numerical differentiation using DQ can be practically utilized in the structural analysis.