• Title/Summary/Keyword: 직접미분법

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Shape Optimum Design of Cantilever with Weight and Journal Bearing Cap (자중을 고려한 외팔보와 저널 베어링 덮개의 형상 최적설계)

  • Lim, O-Kang;Lee, Jin-Suk;Cho, Heon;Lee, Byung-Woo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.3
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    • pp.427-435
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    • 1999
  • In the field of shape optimum design, much efforts are needed in regridding method and shape design sensitivity analysis. In this paper, Bezier curve is used to make the boundary of a structure and the improved direct differentiation method is used to calculate the shape design sensitivity. To regrid the finite element model, modified displacement field is presented in this paper. The modified displacement field makes more fine grid at large curvature. The purpose of this paper is to obtain the optimum shape of a cantilever with weight and a 3-dimensional journal bearing cap.

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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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Kinematic Design Sensitivity Analysis of Suspension systems Using Direct differentiation (직접미분법을 이용한 현가장치의 기구학적 민감도해석)

  • 민현기;탁태오;이장무
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.1
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    • pp.38-48
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    • 1997
  • A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

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Design Sensitivity Analysis of Welded Strut Joints on Vehicle Chassis Frame (샤시 프레임에 용접한 스트러트 접합부의 설계 민감도 해석)

  • 김동우;양성모;김형우;배대성
    • Journal of Welding and Joining
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    • v.16 no.3
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    • pp.141-147
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    • 1998
  • Design sensitivity analysis of a vehicle system is an essential tool for design optimization and trade-off studies. Most optimization algorithms require the derivatives of cost and constraint function with respect to design in order to calculate the next improved design. This paper presents an efficient algorithm application for the design sensitivity analysis, using the direct differentiation method. A mounting area of suspension that welded on chassis frame is analyzed to show the validity and the efficiency of the proposed method. A mounting area of suspension that welded on chassis frame is analyzed to show the validity and the efficiency of the proposed method.

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

  • 전형호;탁태오
    • Journal of the Korean Society for Railway
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    • v.5 no.1
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    • pp.40-47
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    • 2002
  • In this study, and analytical method for ride sensitivity analysis of a train with non-linear suspension elements are proposed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train are parameterized using polynomial interpolation. Vertical dynamic model of a three-body train running on straight rail with the predetermined roughness expressed in terms of spectral density function is set up and its equations of motion for ride analysis are derived. Using the direct differentiation method, sensitivity equations of the vertical dynamic model with respect to design parameters associated with non-linearity of suspensions are obtained. Based on the sensitivity analysis, improvement of ride is achieved by varying appropriate suspension parameters.

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.

Probabilistic finite Element Analysis of Eigenvalue Problem- Buckling Reliability Analysis of Frame Structure- (고유치 문제의 확률 유한요소 해석)

  • 양영순;김지호
    • Computational Structural Engineering
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    • v.4 no.2
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    • pp.111-117
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    • 1991
  • The analysis method calculating the mean and standard deviation for the eigenvalue of complicated structures in which the limit state equation is implicitly expressed is formulated and applied to the buckling analysis by combining probabilistic finite element method with direct differential method which is a kind of sensitivity analysis technique. Also, the probability of buckling failure is calculated by combining classical reliability techniques such a MVFOSM and AFOSM. As random variables external load, elastic modulus, sectional moment of inertia and member length are chosen and Parkinson's iteration algorithm in AFOSM is used. The accuracy of the results by this study is verified by comparing the results with the crude Monte Carlo simulation and Importance Sampling Method. Through the case study of some structures the important aspects of buckling reliability analysis are discussed.

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A Study on the Static Sensitivity Analysis Algorithm Using the Transfer of Stiffness Coefficient (강성계수의 전달을 이용한 정적 감도해석 알고리즘에 관한 연구)

  • Choi, Myung-Soo
    • Journal of Power System Engineering
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    • v.5 no.4
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    • pp.82-89
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    • 2001
  • To design a structural or a mechanical system with the best performance, the main procedure of a typical design usually consists of repeated modifications of design parameters and the investigation of the system response for each set of these parameters. But this procedure requires much time, effort and experience. Sensitivity analysis can provide systematic information for improving performance of a system. The author has studied on the development of the structural analysis algorithm and suggested recently the transfer stiffness coefficient method(TSCM). This method is very suitable algorithm to a personal computer because the concept of the TSCM is based on the transfer of the nodal stiffness coefficients which are related to force and displacement vectors at each node. In this paper, a new sensitivity analysis algorithm using the concept of the TSCM is formulated for the computation of state variable sensitivity in static problems. The trust of the proposed algorithm is confirmed through the comparison with the computation results using existent sensitivity analysis algorithm and reanalysis for computation models.

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Optimum Design of Automobile Seat Upper Arm Using Finite Elements (유한요소를 이용한 자동차 시트 어퍼암의 최적설계)

  • 임오강;이진식;노효철;최정묵
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.2
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    • pp.135-141
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    • 2001
  • 차량 충돌시 자동차의 시트는 승객 및 운전자를 보호해야 한다. 따라서 자동차시트는 충분한 강도를 가져야 하며 이것은 여러 가지 법규에 의해서 제재되고 있다. 물리적 실험 결과가 법규에 정한 규정치를 만족시키기 위해 과대설계 될 수 있다. 그러나 이것은 연비를 줄이기 위한 경량화의 만족이라는 설계요구에 상충한다. 본 논문에서는 헤드레스트 강도시험을 시뮬레이션하고 과대 설계되어 있다고 판단되는 어퍼암을 최적화 모델로 최적설계를 수행하였다. 순차 이차 계획법인 PLBA 알고리즘과 민감도 해석을 위하여 직접근사해석법을 사용하였다.

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Optimal Algorithm from Object Function to Simultaneous Equations by Direct Derivative (목적 함수의 연립 방정식화를 위한 직접 도함수 산출에 의한 최적치 계산법)

  • 김주홍;엄기환
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.1
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    • pp.155-163
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    • 2000
  • In this paper, we propose an algorithm for the object function used in optimal control or optimal design that sets the object function as simultaneous and then calculates the optimal value according to the Newton method. The proposed method calculates the optimal value simply using two inputs; object function and initial value, using the DDA(Direct Derivative Algorithm) which is a programmed ordinary derivative function that does not inquire the calculation of derivative function nor any inputs. And we have verified the usefulness of the algorithm for the optimal control and optimal dosing.

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