• Title/Summary/Keyword: sensitivity analysis

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An Efficient Algorithm for Design Sensitivity Analysis of railway Vehicle Systems (철도차량의 설계 민감도 해석을 위한 효율적인 알고리즘 개발)

  • 배대성;조희제;백성호;이관섭;조연옥
    • Proceedings of the KSR Conference
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    • 1998.05a
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    • pp.299-306
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    • 1998
  • Design sensitivity analysis of a mechanical system is an essential tool for design optimization and trade-off studies. This paper presents an efficient algorithm for the design sensitivity analysis of railway vehicle systems, using the direct differentiation method. The cartesian coordinate is employed as the generalized coordinate. The governing equations of the design sensitivity analysis are formulated as the differential equations. Design sensitivity analysis of railway vehicle systems is performed to show the validity and efficiency of the proposed method.

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Displacement-Load Method for Semi-Analytical Design Sensitivity Analysis (준해석 설계민감도를 위한 변위하중법)

  • Yoo Jung Hun;Kim Heung Seok;Lee Tae Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.10
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    • pp.1590-1597
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    • 2004
  • Three methods of design sensitivity analysis for structures such as numerical method, analytical method and semi-analytical method have been developed for the last three decades. Although analytical design sensitivity analysis can provide very exact result, it is difficult to implement into 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 fur most linear problems. However, it turns out that the numerical differentiation is inefficient and inaccurate in nonlinear design sensitivity analysis because its computational cost depends on the number of design variables and large numerical errors can be included. Thus the 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 fur the semi-analytical design sensitivity analysis outside of the commercial finite element package is studied and the computational technique is proposed for evaluating the partial differentiation of internal nodal force, so called pseudo-load. Numerical examples coupled with commercial finite element package are shown to verify usefulness of proposed semi-analytical sensitivity analysis procedure and computational technique for pseudo-load.

Sensitivity and optimisation procedures for truss structures under large displacement

  • Bothma, A.S.;Ronda, J.;Kleiber, M.
    • Structural Engineering and Mechanics
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    • v.7 no.1
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    • pp.111-126
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    • 1999
  • The work presented here focuses on the development of suitable discretised formulations, for large-displacement shape and non-shape design sensitivity analysis (DSA), which enable the straightforward incorporation of structural optimisation into established finite element analysis (FEA) codes. For the generalised displacement-based functional the design sensitivity vector has been expressed in terms of displacement sensitivity. The Total Lagrangian formulation is utilised for modelling of large deformation of truss structures. The variational formulation of the sensitivity analysis procedure is discretised by using "pseudo" - finite elements, Results are presented for the sensitivity analysis and optimisation of standard truss structures. For the purposes of this work, the analysis and optimisation procedures outlined below are incorporated into the FEA code ABAQUS.

Optimal Design of Vehicle Suspenion Systems Using Sensitivity Analysis (민감도 해석을 이용한 현가장치의 동역학적 최적설계)

  • 탁태오
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.3
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    • pp.50-61
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    • 1994
  • A method for performing dynamic design sensitivity analysis of vehicle suspension systems which have three dimensional closed-loop kinematic structure is presented. A recursive form of equations of motion for a MacPherson suspension system is derived as basis for sensitivity analysis. By directly differentiating the equations of motion with respect to design variables, sensitivity equations are obtained. The direct generalize for the application of multibody dynamic sensitivity analysis. Based on the proposed sensitivity analysis, optimal design of a MacPherson suspension system is carried out taking unsprung mass, spring and damping coefficients as design variables.

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Shape Design Sensitivity Analysis using Isogeometric Approach (CAD 형상을 활용한 설계 민감도 해석)

  • Ha, Seung-Hyun;Cho, Seon-Ho
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.577-582
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    • 2007
  • A variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions in analysis domain arc generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Thus. the solution space can be represented in terms of the same functions to represent the geometry. The coefficients of basis functions or the control variables play the role of degrees-of-freedom. Furthermore, due to h-. p-, and k-refinement schemes, the high order geometric features can be described exactly and easily without tedious re-meshing process. The isogeometric sensitivity analysis method enables us to analyze arbitrarily shaped structures without re-meshing. Also, it provides a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling. To obtain precise shape sensitivity, the normal and curvature of boundary should be taken into account in the shape sensitivity expressions. However, in conventional finite element methods, the normal information is inaccurate and the curvature is generally missing due to the use of linear interpolation functions. A continuum-based adjoint sensitivity analysis method using the isogeometric approach is derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of boundary. In isogeometric analysis, however, the geometric properties arc already embedded in the B-spline shape functions and control points. The perturbation of control points in isogeometric analysis automatically results in shape changes. Using the conventional finite clement method, the inter-element continuity of the design space is not guaranteed so that the normal vector and curvature arc not accurate enough. On tile other hand, in isogeometric analysis, these values arc continuous over the whole design space so that accurate shape sensitivity can be obtained. Through numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

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The Sensitivity Analysis of Parameters of Urban Runoff Models due to Variations of Basin Characteristics (I) - Development of Sensitivity Analysis Method - (유역특성 변화에 따른 도시유출모형의 매개변수 민감도분석(I) -민감도분석방법의 개발-)

  • Seo, Gyu-U;Jo, Won-Cheol
    • Journal of Korea Water Resources Association
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    • v.31 no.3
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    • pp.243-252
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    • 1998
  • In this study, the new dimensionless values were defined and proposed to determine the parameters of urban runoff models based on the relative sensitivity analysis. Also, the sensitivity characteristics of each parameter were investigate. In order to analyze the parameter sensitivities of each model, total runoff ratio, peak runoff ratio, runoff sensitivity ratio, sensitivity ratio of total runoff, and sensitivity ratio of peak runoff were defined. $$Total\;runoff\;ratio(Q_{TR})\;=\;\frac{Total\;runoff\;of\;corresponding\;step}{Maximum\;total\;runoff}$$$$Peak\;runoff\;ratio(Q_{PR})\;=\;\frac{Peak\;runoff\;of\;corresponding\;step}{Maximum\;peak\;runoff}$$$$Runoff\;sensitivity\;ratio(Q_{SR})\;=\;\frac{Q_{TR}}{Q_{PR}}$$ And for estimation of sensitivity ratios based on the scale of basin area, rainfall distributions and rainfall durations in ILLUDAS & SWMM, the reasonable ranges of parameters were proposed.

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Design Sensitivity Analysis for the Vibration Characteristic of Vehicle Structure (수송체 구조물의 진동특성에 관한 설계민감도 해석)

  • 이재환
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1992.10a
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    • pp.19-24
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    • 1992
  • Design sensitivity analysis method for the vibration of vehicle structure is developed using adjoint variable method. A variational approach with complex response method is used to derive sensitivity expression. To evaluate sensitivity, FEM analysis of ship deck and vehicle structure are performed using MSC/NASTRAN on the super computer CRAY2S, and sensitivity computation is carried on PC. The accuracy of sensitivity is verified by the results of finite difference method. When compared to structural analysis time on CRAY2S, sensitivity computation is remarkably economical. The sensitivity of vehicle frame can be used to reduce the vibration responses such as displacement and acceleration of vehicle.

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Design Sensitivity Analysis of Zwicker's Loudness Using Adjoint Variable Method (보조변수법을 이용한 Zwicker 라우드니스의 설계민감도)

  • Wang, Se-Myung;Kwon, Dae-Il;Kim, Chaw-Il
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1432-1436
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    • 2006
  • Feasibility of optimizing Zwicker's loudness has been shown by using MSC/NASTRAN, SYSNOISE, and a semi-analytical design sensitivity by Wang and Kang. Design sensitivity analysis of Zwicker's loudness is developed by using ANSYS, COMET, and an adjoint variable method in order to reduce computation. A numerical example shows significant reduction of computation time for design sensitivity analysis.

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Ride Sensitivity Analysis of a Train Model with Non-linear Suspension Elements (비선형 현가요소를 가진 철도차량의 승차감 민감도 해석)

  • Tak, Tae-oh;Kim, Myung-hun
    • Journal of Industrial Technology
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    • v.18
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    • pp.233-240
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    • 1998
  • In this study, ride sensitivity analysis of train with non-linear suspension elements is performed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train is parameterized. Equation of motion of the train model is derived, and using the direct differentiation method, sensitivity equations are obtained. For a nominal ride quality performance index, sensitivity analysis with respect to various design parameters regarding non-linear suspension parameters is carried out.

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Sensitivity Analysis of Processing Parameters for the Laser Surface Hardening Treatment by Using the Finite Element Method (유한요소법을 이용한 레이저 표면경화처리 공정변수의 민감도 해석)

  • 이세환;양영수
    • Journal of Welding and Joining
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    • v.19 no.2
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    • pp.228-234
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    • 2001
  • A methodology is developed and used to evaluate the response sensitivity of the thermal systems to variations in their design parameters. Technique for computing the sensitivity of temperature distributions to changes in processing parameters needed to decide the more effective laser input parameters for laser surface hardening treatment is considered. In this study, a state equation governing the heat flow in laser surface treatment is analyzed using a three-dimensional finite element method and sensitivity data of the processing parameter obtained using a direct differentiation method is applied to the sensitivity analysis. The interesting processing parameters are taken as the laser scan velocity and laser beam radius ( $r_{ b}$), and the sensitivities of the temperature T versus v and $r_{b}$ are analyzed. These sensitivity results are obtained with another parameters fixed. To verify the numerical analysis results, hardened layer dimensions (width and depth) of the numerical analysis are compared with the experimental ones.nes.

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