막 구조물의 삼각형 Re-mesh 패턴을 적용한 재단도 생성에 관한 연구

전진형,손수덕,정을석,김승덕,Jeon, Jin-Hyung,Shon, Su-Deok,Jeong, Eul-Seok,Kim, Seung-Deog 한국공간구조학회 2007 한국공간구조학회지 Vol.7 No.3

연성 구조물은 축강성은 강하고 휨 강성이 매우 작은 재료를 주 구조재로 사용하므로 초기강성에 매우 민감한 구조체이다. 막 구조물을 설계하기 위해서는 우선 초기장력 도입으로 인한 구조물의 형상을 정확히 알아야 한다. 이를 위해서 모형을 통한 모델링이나 컴퓨터를 이용한 형상해석이 요구되며, 초기장력의 도입으로 형성되는 막 구조물의 곡면은 일반적으로 등장력 곡면이다. 따라서 연성 구조물의 해석과 설계는 기존의 강성구조물과는 다른 형상해석, 응력-변형해석, 재단도 작성 및 시공해석의 3단계 해석이 요구되어진다. 본 연구는 재단도 작성 프로그램 NASScut를 이용하여 경계면 곡률의 오차를 최소화 할 수 있는 삼각형 Re-mesh 패턴을 제안하고, 재단도를 작성한다. Flexible structure uses a material with strong axial stiffness and small bending stiffness as its major structural material so it is very sensitive to initial stiffness. Therefore, the self-formation process which accomplishes a form in the natural world is grasped and it is as well investigated and classified the type of modeling techniques which are available to find the shapes of soft structures. Accordingly, for analysis and design of flexible structure, three-step analysis such as shape analysis, stress-deformation analysis, cutting pattern generation and constructional analysis is required unlike the existing stiff structure. In this study, suggest that minimize the error of side curvatures by the triangle Re-mesh pattern and draw the cutting pattern generation.

개선소성힌지해석과 유전자 알고리듬을 이용한 평면 강골조 구조물의 퍼지최적설계

이말숙,윤영묵,손수덕,Lee, Mal Suk,Yun, Young Mook,Shon, Su Deok 한국강구조학회 2006 韓國鋼構造學會 論文集 Vol.18 No.2

본 논문에서는 개선소성힌지해석과 유전자 알고리듬을 이용한 평면 강골조 구조물의 퍼지최적설계 방법을 제시하였다. 개선소성힌지해석에서는 강골조 구조물의 기하학적 비선형성을 고려하기 위해 보-기둥 요소의 안정함수를 사용하였으며, 재료적 비선형을 고려하기 위해 잔류응력, 소성힌지, 그리고 기하학적 불완전성 등에 의한 점진적인 강성감소모델을 사용하였다. 유전자 알고리듬에서는 토너먼트 선택방법과 마이크로 유전자 알고리즘을 사용하였다. 목적함수로는 구조물의 총중량을 사용하였으며, 제약조건으로는 하중-저항능력, 사용성, 연성도, 그리고 시공성에 관한 기준을 고려하였다. 퍼지최적설계에서는 명확한 목적함수와 퍼지제약을 가지는 경우에 한하여 허용 오차는 제한값의 5%로 선택하고 비소속함수와 레벨컷 방법을 이용하여 0에서 1까지 0.2간격으로 나누어 최적화하였다. 여러 평면 강골조 구조물의 최적설계를 수행하여 일반GA최적설계와 퍼지GA최적설계의 최적값을 비교하였다. GA-based fuzzy optimum design algorithm incorporated with the refined plastic hinge analysis method is presented in this study. In the refined plastic hinge analysis method, geometric nonlinearity is considered by using the stability functions of the beam-column members. Material nonlinearity is also considered by using the gradual stiffness degradation model, which considers the effects of residual stresses, moment redistribution through the occurence of plastic hinges, and the geometric imperfections of the members. In the genetic algorithm, the tournament selection method and the total weight of the steel frames. The requirements of load-carrying capacity, serviceability, ductility, and constructabil ity are used as the constraint conditions. In fuzzy optimization, for crisp objective function and fuzzy constraint s, the tolerance that is accepted is 5% of the constraints. Furthermore, a level-cut method is presented from 0 to 1 at a 0 .2 interval, with the use of the nonmembership function, to solve fuzzy-optimization problems. The values of conventional GA optimization and fuzzy GA optimization are compared in several examples of steel structures.

등기하해석법을 적용한 평면구조물의 위상최적화

박경임(Park, Gyeong-Im),이상진(Lee, Sang-Jin) 대한건축학회 2016 大韓建築學會論文集 : 構造系 Vol.32 No.2

In this paper, the isogeometric topology optimization (TO) technique is presented for plane structures. Isogeometric concept uses the same NURBS basis functions for both the computer-aided geometric design (CAGD) representation and the field functions. Therefore, the exact geometric models are naturally used in TO process. In addition, the NURBS basis functions are consistently used as the material distribution functions. Since the point-wise design variables are adopted, the proposed TO technique is completely free from checker boarding phenomenon without additional constraints or a filtering technique. The validity and applicability of the presented TO technique are demonstrated by solving TO problems for plane structures and we also investigate the effect of isogeometric analysis parameters to the optimum topology.

등기하해석법을 이용한 자유진동 평면구조물의 위상최적화

이상진(Lee, Sang-Jin),배정은(Bae, Jungeun) 대한건축학회 2018 大韓建築學會論文集 : 構造系 Vol.34 No.6

Isogeometric concept is introduced to find out the optimum layout of plane structure under free vibration. Eigenvalue problem is formulated and numerically solved in order to obtain natural frequencies and mode shapes of plane structures. For the exact geometric expression of the structure, the Non-Uniform Rational B-spline Surface (NURBS) basis functions is employed and it is also used to define the material density functions. A node-wise design variables is adopted to deal with the updating of material density in topology optimization (TO). The definition of modal strain energy is employed to achieve the maximization of fundamental frequency through its minimization. The verification of the proposed TO technique is performed by a series of benchmark test for plane structures.

鋼뼈대 構造物의 塑性安定 解釋에 관한 理論的 硏究

이종석(J. S. Lee) 한국해양공학회 1988 韓國海洋工學會誌 Vol.2 No.2

For the collapse of structures due to the variable repeated load, two types of collapse mechanisms, i.e., incremental collapse and alternating plasticity, exist. Under the similar variable repeated loading conditions there exists shakedown state in the structures. In shakedown state, the number of plastic hinges are not increased and all further loading will be resulted in the elastic moment changes. Namely, under the shakedown state, structures do not collapse.<br/> In this investigation, shakedown analysis are performed by composing new computer programs. Basic theories employed to compose the programs are as follows.<br/> 1. Newton-Raphson methods are added to the existing matrix method for the plastic analysis.<br/> 2. An effort to construct the stiffness of axial and bending springs attached at both ends of the member has been made.<br/> By using the programs developed, it is possible to anticipate the collapse mechanisms(Incremental collapse, alternating plasticity). Lastly for the verification of performance of the program, demonstration examples have been solved and the results are compared with other sources.

수정-서브플랜을 이용한 막 구조물의 측지선 탐색과 곡선 재단도 작성에 관한 연구

손수덕(Shon, Su-Deok),이승재(Lee, Seung-Jae) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.12

This paper investigated a simple and useful technique of smooth geodesic cutting patterning of membrane structures and a sub-plane on surface, modified sub-plane and spline interpolation are used for geodesic line search. Firstly, a partial adjustment and element redirection of sub-plane of extracted elements series and substituting alternative nodal point were proposed for the geodesic search with modification of sub-plane. Secondly various spline approximations were applied to flatten the strip for the generation of smooth cutting pattern. This search technique is very simple enough to attain the geodesic line without difficult mathematical or computational method. Additionally, seam line of smooth cutting patterning also can be generated by spline approximation by using the geometric information of discrete nodes. The geodesic line of the cable-supported pneumatic membrane model with 670 nodes and 1188 triangular elements are examined, and cutting pattern of arch-supported membrane model are generated to verify the process of smooth cutting pattern generation.

정사각형 외팔보에서의 일대일 공진

김명구(Kim, Myoung-Gu),박철희(Pak, Chul-Hui),조종두(Cho, Chong-Du) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.7

The response characteristics of one to one resonance on the quadrangle cantilever beam in which basic harmonic excitations are applied by nonlinear coupled differential-integral equations are studied. This equations have 3-dimensional non-linearity of nonlinear inertia and nonlinear curvature. Galerkin and multi scale methods are used for theoretical approach to one-to-one internal resonance. Nonlinear response characteristics of 1st, 2nd, 3rd modes are measured from the experiment for basic harmonic excitation. From the experimental result, geometrical terms of non-linearity display light spring effect and these terms play an important role in the response characteristics of low frequency modes. Nonlinear nitration in the out of plane are also studied.

원형 외팔보의 응답에서의 비선형 현상

김명구(Kim, Myung-Gu),이흥식(Lee, Heung-Shik),조종두(Cho, Chong-Du) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.4

This paper is the result of a experimental study about non-linear one to one modal coupling of a flexible circular cantilever beam which was transversely excited with harmonic excitation. It was proved that 2 order jumping in out of plane was caused by jump phenomenon in in-plane of flexible circular cantilever beam, because of non-linear coupling. In addition, cantilever beam showed hardening spring characteristics in in-plane and softening spring characteristics in out-of-plane.

평면 차체프레임구조물의 민감도해석 및 최적설계

이종선,김엽래,이강손 한국공작기계학회 1996 한국생산제조학회지 Vol.5 No.4

This paper is to estimate sizing design sensitivity of linear and nonlinear vehicle frame structure using structural analysis result from ANSYS. Using design sensitivity results, optimal design of plane vehicle frame structure with buckling constraint is carried out the gradient projection method. Optimal design results are compares gradient projection method result with SUMT result.

Tug에 의한 반잠수식 해양 구조물 위치 유지를 위한 제반 파라메터 검토

이진호(Jin Ho Lee),박준흠(Jun Heum Park),장학수(Hag Soo Jang) 한국해양공학회 2014 韓國海洋工學會誌 Vol.28 No.4

This paper investigates the line dynamic forces connecting tugs and a floater, where the planar motion of the floater is due to the weather criteria during the position keeping of the offshore structure by tugs. The analysis situation consists of the position keeping states for the seabed mooring line connection work of the offshore structure at the offshore site. Specifically, the decision about the tug power capacity for the position keeping is essential and depends on the weather criteria, line characteristics, length of line, etc. The planar motion of the structure is constrained by the interference of the installation vessels operational range, behavior of the underwater fairlead, and other surrounding structures. In this paper, the tug line forces and planar motion of an offshore structure are summarized dependent on the tug line length and line material characteristics in the states for a given floater draft and weather criteria. The tug line dynamic forces and planar motion evaluated here will be used to determine the proper tug power and clearance of an offshore structure.