• Title/Summary/Keyword: Sensitivity analysis

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Reliability-Based Optimization using Sensitivity Analysis of Reliability Index (신뢰성 지수의 민감도 해석을 이용한 신뢰성에 기초한 최적설계)

  • 조효남;민대홍;권우성
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2000.10a
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    • pp.101-108
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    • 2000
  • An optimum design algorithm using efficient reanalysis is proposed for reliability-based optimization problems formulated as the minimization of initial cost and expected failure cost with reliability constraints. The reliability-based optimization is high cost to evaluate objective function and constraints needed reliability analysis. Therefore the sensitivity analysis of reliability index for approximated reanalysis is necessary. In this paper, three solution approaches are suggested and tested. The approaches include : (1) sensitivity analysis using finite difference; (2) sensitivity analysis using automatic differentiation (AD); and (3) sensitivity analysis with respect to intermediate variables using AD. Numerical example is optimized to show the reliability and effectiveness of the new algorithm.

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Modelling and Sensitivity Analysis for the Performance Improvement of a Spin Coater (스핀 코너 성능향상을 위한 모델링 및 민감도 해석)

  • 권태종;채호철;한창수;정진태;안강호
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.96-102
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    • 2000
  • Spinning mechanism is generally used in coasting process on grass plates. Rebounding PR(Photo Resist) which leads to occur inferiority of coating process is caused by vibrational energy of whole coating system. In this study, the sensitivity analysis is performed to analyze and reduce vibrational terms in the spin coating system. The sensitivity analysis is bared on the numerical expression of this system. By the bond graph method. power flow of each system is represented by some basic bond graph elements. Any energy domain system is modeled using the unified elements. The modelled spin coater system is verified with power spectrum data measured by FFT analyzer. As the results of verifying model parameters and sensitivity analysis, principal factors causing vibration phenomenon are mentioned. A study on vibration method in the spin coating system is discussed.

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Shape Design Sensitivity Analysis of Two-Dimensional Thermal Conducting Solids with Multiple Domains Using the Boundary Element Method (경계요소법을 이용한 2 차원 복수 영역 열전도 고체의 형상 설계 민감도 해석)

  • 이부윤;임문혁
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.8
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    • pp.175-184
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    • 2003
  • A method of the shape design sensitivity analysis based on the boundary integral equation formulation is presented for two-dimensional inhomogeneous thermal conducting solids with multiple domains. Shape variation of the external and interface boundary is considered. A sensitivity formula of a general performance functional is derived by taking the material derivative to the boundary integral identity and by introducing an adjoint system. In numerical analysis, state variables of the primal and adjoint systems are solved by the boundary element method using quadratic elements. Two numerical examples of a compound cylinder and a thermal diffuser are taken to show implementation of the shape design sensitivity analysis. Accuracy of the present method is verified by comparing analyzed sensitivities with those by the finite difference. As application to the shape optimization, an optimal shape of the thermal diffuser is found by incorporating the sensitivity analysis algorithm in an optimization program.

Eigen-sensitivity Analysis of Augmented System State Matrix (전력계통의 확대상태행렬 고유치감도 해석)

  • Shim, Kwan-Shik;Nam, Hae-Kon;Kim, Yong-Gu
    • Proceedings of the KIEE Conference
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    • 1996.07b
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    • pp.749-753
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    • 1996
  • This paper presents a new method for first and second order eigen-sensitivity analysis of system matrix in augmented form. Eigen-sensitivity analysis provides invaluable informations in power system planning and operation. However, conventional eigen-sensitivity analysis methods, which need all the eigenvalues and eigenvectors, can not be applicable to large scale power systems due to large computer memory and computing time required. In the proposed method, all sensitivity computations for a mode are carried out using the augmented system matrix and its own eigenvalue and right & left eigenvectors. In other words sensitivity analysis for a mode does not need informations on the other eigenvalues and eigenvectors and sparsity technique can be fully utilized. Thus compuations can be done very efficiently with moderate computer memory and computing time even for large power systems. The proposed algorithm is tested for one machine infinite bus system.

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Improvement of Steering-Wheel Idle Vibration in a Passenger Car using Design Sensitivity Analysis (설계민감도 해석을 이용한 승용차의 스티어링 휠 아이들 진동 개선)

  • 이두호;김명업
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.2
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    • pp.129-137
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    • 2000
  • In the prototype stage of a car developing program, the efficiency of trouble shooting is an important factor to be considered. Structural modifications by the design sensitivity analysis are applied to a steering wheel system for improving the idle vibration of the prototype passenger car. For the design sensitivity analysis, the experimental modal analysis for the steering system attached to a body-in-white is fulfilled and the modal parameters extracted from the experimental data are used to predict the effect of structural modification, The design sensitivity results rank the locations to be reinforced in terms of frequency variation. The modification of steering system according to the sensitivity analysis results shifted the resonant frequency of the system effectively. In addition, the idle test of the car after the structural modifications f steering system shows that the proposed method can reduce vibration of the steering wheel efficiently.

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Design Sensitivity Analysis of Elasto-perfectly-plastic Structure for Stiffened Shell Structure (탄성-완전-소성 보강쉘 구조물의 설계민감도해석)

  • Jung, Jae-Joon;Lee, Tae-Hee;Lim, Jang-Keun
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.746-752
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    • 2001
  • Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

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Direct Differentiation Method for Shape Design Sensitivity Analysis of Axisymmetric Elastic Solids by the BEM and Shape Optimization of Turbin Disc (경계요소법에 의한 축대칭 탄성체의 형상설계 민감도해석을 위한 직접미분법과 터빈 디스크의 형상최적설계)

  • Lee, Bu-Yun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.5
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    • pp.1458-1467
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    • 1996
  • A direct differentiationmethod is presented for the shape design sensitivity analysis of axisymmeetric elastic solids. Based on the exisymmetric boundary integralequaiton formulation, a new boundary ntegral equatio for sensitivity analysis is derived by taking meterial derivative to the same integral identity that was used in the adjoint variable melthod. Numerical implementation is performed to show the applicaiton of the theoretical formulation. For a simple example with analytic solution, the sensitivities by present method are compared with analytic sensitivities. As an application to the shape optimization, an optimal shape of a gas turbine disc toinimize the weight under stress constraints is found by incorporating the sensitivity analysis algorithm in an optimizatio program.

Finite element response sensitivity analysis of continuous steel-concrete composite girders

  • Zona, Alessandro;Barbato, Michele;Conte, Joel P.
    • Steel and Composite Structures
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    • v.6 no.3
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    • pp.183-202
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    • 2006
  • The behavior of steel-concrete composite beams is strongly influenced by the type of shear connection between the steel beam and the concrete slab. For accurate analytical predictions, the structural model must account for the interlayer slip between these two components. This paper focuses on a procedure for response sensitivity analysis using state-of-the-art finite elements for composite beams with deformable shear connection. Monotonic and cyclic loading cases are considered. Realistic cyclic uniaxial constitutive laws are adopted for the steel and concrete materials as well as for the shear connection. The finite element response sensitivity analysis is performed according to the Direct Differentiation Method (DDM); its analytical derivation and computer implementation are validated through Forward Finite Difference (FFD) analysis. Sensitivity analysis results are used to gain insight into the effect and relative importance of the various material parameters in regards to the nonlinear monotonic and cyclic response of continuous composite beams, which are commonly used in bridge construction.

Sensitivity Analysis of Shear Strength Parameters($C, _{\Phi}$)and Slope Angel in Slope Stability Analysis (사면 안정해석에 적용되는 지반강도정수($C, _{\Phi}$)와 사면경사 민감도 분석)

  • Baek, Yong;Bae, Gyu-Jin;Kwon, O-Il;Jang, Su-Ho;Koo, Ho-Bon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.179-184
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    • 2005
  • Shear strength parameters obtained from filed survey are important factors in the analysis of slope stability. In this study, sensitivity analysis was performed to evaluate the effect of input parameters on the analysis of slope stability. The input parameters selected for sensitivity analysis were slope angle, cohesion, and friction angle. Monte-Carlo Simulation method was used for calculating input parameters and the factor of safety was computed by means of limit equilibrium method. A rock slope, which has failed in the field, was used for the sensitivity analysis in the analysis of slope stability. The result of analysis shows that the factor of safety of the rock slope was a little low. From partial correlation coefficient(PPC) of input parameters determined from the sensitivity analysis, slope stability was dependant on cohesion and slope angle. The effect of friction angle was lower than that of cohesion and slope angle on slope stability.

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Sensitivity Analysis of Input Parameters in Slope Stability Analysis (사면 안정해석에 적용되는 입력 인자들의 민감도 분석)

  • Baek Yong;Bae Gyu-Jin;Kwon O-Il;Chang Soo-Ho;Koo Ho-Bon
    • Journal of the Korean Geotechnical Society
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    • v.21 no.5
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    • pp.75-82
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    • 2005
  • Shear strength parameters obtained from field tests are important factors in the analysis of slope stability. In this paper, sensitivity analysis was performed to evaluate the effect of input parameters on the analysis of slope stability. The input parameters selected for sensitivity analysis were slope angle, cohesion, and friction angle. Monte-Carlo Simulation method was to estimate input parameters for sensitivity analysis in slope stability, and the limit equilibrium method was used to calculate the factor of safety of slope stability. A rock slope, failed in the field, was used for the sensitivity analysis of input parameters in the analysis of slope stability. The result of analysis shows that the factor of safety of the rock slope was a little low. From partial correlation coefficient (PCC) of input parameters from the sensitivity analysis, slope stability was dependant mainly on cohesion and slope angle. The effect of friction angle was smaller than those of cohesion and slope angle on slope stability.