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최주호(Joo-Ho Choi),양욱진(Wook-Jin Yang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
This paper addresses a method for shape design sensitivity analysis of a buckling load in a continuous elastic body. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Though the buckling problem is more efficiently solved by structural elements such as a beam and shell, elastic solids have been chosen for the buckling analysis in this paper because solid elements can generally be used for any kind of structure whether it is thick or thin. Sensitivity is then computed by using the mathematical package MATLAB with the initial stress and buckling analysis of ANSYS. Several problems are chosen in order to illustrate the efficiency of the presented method. They are applied to the shape optimization problems to minimize weight under allowed critical loads.
최주호(J.H. Choi),곽현구(H.G. Kwak),R. Grandhi 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
An efficient boundary-based technique is developed for addressing shape design sensitivity analysis in supercavitating flow problem. An analytical sensitivity formula in the form of a boundary integral is derived based on the continuum formulation for a general functional defined in potential flow problems. The formula, which is expressed in terms of the boundary solutions and shape variation vectors, can be conveniently used for gradient computation in a variety of shape design in potential flow problems. While the sensitivity can be calculated independent of the analysis means, such as the finite element method (FEM) or the boundary element method (BEM), the FEM is used for the analysis in this study because of its popularity and easy-to-use features. The advantage of using a boundary-based method is that the shape variation vectors are needed only on the boundary, not over the whole domain. The boundary shape variation vectors are conveniently computed by using finite perturbations of the shape geometry instead of complex analytical differentiation of the geometry functions. The supercavitating flow problem is chosen to illustrate the efficiency of the proposed methodology. Implementation issues for and optimization procedure are addressed in this flow problem.
이상범 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.6
Vibrational characteristics of the vehicle structure are mainly influenced us the shape of the pillar cross section. In this paper a vehicle structural optimization technique has been developed to investigate a lightweight vehicle structure subject to constraints on natural frequencies in a simple beam-and-shell model. In this technique, the optimization procedures ins oh e two stages. In the first stage, the section properties of beam elements of the vehicle structure has been optimized to have minimum is eight while satisfying the constraints of natural frequencies. And, in the second stage, the shape of the cross section of the elements of the structure has been determined.
다중 조밀도를 이용한 탄성 구조의 h-세분화 아이소-지오메트릭 설계민감도 해석
이태호,윤민호,조선호,구본용 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.3
본 논문은 아이소-지오메트릭 해석에서 h-세분화를 이용한 국부 세분화법과 이에 따른 설계 민감도 해석의 방법론을 연 구하였다. 다중 조밀도 방식을 이용하여 경계면에서 변위 적합조건을 만족하였고, 기존의 아이소-지오메트릭 해석의 텐서곱 으로 인해 발생하는 원치 않는 자유도 증가의 문제를 극복하였다. 해석에서의 변위 적합조건과 마찬가지로, 설계 민감도 해석에서도 변위 결과와 마찬가지로 똑같은 적합조건을 만족하도록 하는 방법론을 제시하였다. 수치 예제를 통하여 본 방법론의 효율성을 입증하였고, 특별히 응력 집중 문제에서의 결과와 민감도 값을 비교하며 경계면에서의 적합조건을 확인하였다. One of the major disadvantages of isogeometric analysis(IGA) is that local refinement is nearly impossible in a conventional manner because of the tensor product nature in NURBS. In this research, we investigate a local refinement scheme for isogeometric analysis, named multi-resolution approach where different resolutions are employed at each subdomain, using h-refinement relation to endow displacement compatibility on an interface of subdomains. Then, we develop shape sensitivity analysis possessing same compatibility condition as in the analysis. Numerical examples are shown to demonstrate the computational efficiency of the method in analysis especially stress concentration problem and accurate sensitivity results which is also compatible on the interface.