우주용 복합재 격자 강화 구조 제작 방법

이주훈(Rhee, Juhun) 한국항공우주연구원 2016 항공우주산업기술동향 Vol.14 No.1

일반적으로 격자 강화 구조는 가볍고, 강성이 우수한 구조물을 만드는데 널리 활용되며, 발사체 및 위성체 등에 적용되고 있다. 본 논문의 격자 강화 복합재 패널은 위성의 경량화/소형화를 위한 다기능 구조체의 기층으로, 격자 내의 공간에 전자회로를 장착하기 위하여 제안되었다. 패널의 전체 크기는 860×890×21.14mm3으로, 격자와 면재는 팬계열 CFRP인 M55J 소재를 이용하여 동시경화 공정으로 제작되었다. 면재 및 격자의 적층 각도, 격자 적층 방법, 격자 교차점의 툴 블록 설계 및 제작, 치공구의 소재, 설계 및 제작 등에 대하여 설명하였으며, 이를 통하여 설계 및 제작된 격자 강화 복합재 패널은 랜덤 및 정현파 진동 환경시험으로 검증되었다. Generally, the grid-stiffened structure with the lightweight and excellent stiffness characteristics is widely utilized and applied for the launch vehicle and satellite. The grid-stiffened composite panel of this paper was proposed as the substrate of the structure of the multi-functional structure for the lighter/smaller to provide the available room between the grids for integrating multiple electronic circuitries into the structure. The size of the panel is 860×890×21.14mm3, and the grids and skin were designed to be co-cured with the pan-based CFRP prepreg M55J. The stacking degree of the skin and grids, the stacking method of grids, the design and manufacturing of the tool block of the grids intersection, and the materials, design and manufacturing of the tools were illustrated, the grid-stiffened composite panel designed and manufactured through these were verified using the random and sinusoidal vibration environmental tests.

바우하우스 텍스타일에서의 그리드 형태 연구

문미영(Moon, Mi-young) 한국조형디자인학회 2011 조형디자인연구 Vol.14 No.1

바우하우스 텍스타일은 순수추상 양식의 도입에 의한 기하추상의 영향으로 그리드형식으로 발전되고 바우하우스 형태교육을 통하여 그리드양식을 형성한다. 그리드는 물질의 실현을 상징하는 통일성과 전체성을 함유하며 수평선과 수직선의 교차에 의해 생성되는 그리드는 물질과 정신의 교차에 의한 운동의 원리로 작용한다. 칸딘스키, 클레, 이텐의 형태이론은 수평ㆍ수직의 대비관계와 선의 의한 그리드 구조 연구로 내적요소와 외적요소의 이원적 사고에 의한 구성방식에 적용된다. 수평ㆍ수직의 조형적 대비관계에 의한 대립구조는 바우하우스 텍스타일에서 비대칭구조로 표현된다. 이러한 비대칭 균형원리는 서로 대립하면서 균형을 이루려는 수평ㆍ수직의 이원성에 근거하며 구성에서 통일성과 전체성을 유지하려는데서 기인한다. 본 연구는 바우하우스 형태이론을 중심으로 그리드가 함의하고 있는 구조적 특성을 제시하고, 구조분석을 통하여 수평ㆍ수직성과 반복성을 규정하는데 주안점을 두었다. 바우하우스 텍스타일은 평면을 그리드로 환원시키는 것이었고, 이는 산업직물의 원형을 위한 규격화된 형태의 창조에서 근거하였다. 바우하우스 텍스타일의 구성방식은 소단위의 형태를 반복함으로서 대단위를 형성하는 반복구조로 그리드 간의 위계성을 동등성으로 대치시킨다. 이러한 동등성의 구조는 그리드의 한계를 확장하고 축소할 수 있게 만든다. 바우하우스 텍스타일에서의 그리드는 최소의 표현형식으로 불필요한 구성요소들을 축소하여 순수조형에 이르는 본질적 의미의 표상으로 해석된다. Bauhaus textiles precede the grid form inspired of abstract geometry which is based on pure abstract forms. The grid form of comtemporary textile art came from Bauhaus theory of plastic form which is accepted the spirit of geometry. Bauhaus textiles formulate the grid form receiving theories of Kandinsky, Klee and Itten. In geometry, grid means unity and wholeness which is symbolized matter. Grid can be transferred symbolically to the crossing of a vertical with horizontal which gives an ‘action principle’, such as the crossing of matter and spirit. The oppositional structure of contrasting a vertical with a horizontal makes space asymmetry. There is the principle of asymmetry, which deals with oppositional elements and forms duality of a vertical with horizontal structure. maintaining unity and wholeness. The purpose of this study defines the character of grid structure centering on Bauhaus grid theory, and also considers a vertical with horizontal and repetition through analyzing grid structure. Bauhaus textiles consist the whole unit by repeating the equal one unit. In this case, it can be considered repetitional structure in that process and result are equivalent in the procedure of composition. Grid can be interpreted a symbol of essential meaning which achieves pure form according to reduce to an atomic form as a primary unit.

측면충격하중 하에서 격자체 구조물의 좌굴거동 해석모델

윤경호(K-H Yoon),강흥석(H-S Kang),김형규(H-K Kim),송기남(K-N Song),김우곤(W-G Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3

The drop type impact test and finite element analysis are established for examining the buckling behavior of a grid structure under the lateral impact load. This grid structure is composed several thin plates by laser welding. The finite element model is produced using preprocessor I-DEAS, and solved using nonlinear solver ABAQUS/explicit. Applied boundary conditions for dynamic impact analysis were nearly the same with actual boundary conditions for impact test. However, the dynamic impact parameters of a grid structure are good agreement with test results. Based on these results, the analysis model of the grid structure for FE analysis is adaptable for evaluating the dynamic buckling behavior of a grid structure. These test and analysis results will be adaptable for predicting the dynamic structural integrity of a grid structure not only the axial impact event but also the lateral impact event.

측면충격하중 상태에서 격자구조물의 좌굴거동 해석모델 개선

윤경호(K-H Yoon),허성필(S-P Heo),강흥석(H-S Kang),김형규(H-K Kim),송기남(K-N Song) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.8

The drop type impact test and finite element analysis are established for examining the buckling behavior of a grid structure under the lateral impact load. This grid structure is composed several thin plates by laser welding. The finite element model is produced using preprocessor I-DEAS, and solved using nonlinear solver ABAQUS/explicit. Applied boundary conditions for dynamic impact analysis were nearly the same with actual boundary conditions for impact test. However, the dynamic impact parameters of a grid structure are good agreement with test results. Based on these results, the analysis model of the grid structure for FE analysis is adaptable for evaluating the dynamic buckling behavior of a grid structure. These test and analysis results will be adaptable for predicting the dynamic structural integrity of a grid structure not only the axial impact event but also the lateral impact event.

스트랜드 간격이 좁은 그리드 타입 CFRP 인장보강재 적용 슬래브의단면 높이 및 스트랜드 간격에 따른 휨거동 평가

김경민,박성우 대한건축학회지회연합회 2023 대한건축학회연합논문집 Vol.25 No.1

Grid-type FRP reinforcement has been used as reinforcement for cement composites instead of rebars mainly in offshore structures due to its corrosion-resistant properties. Recently, the structural application of grid-type FRP reinforcement has been expanded in order to reduce the weight of members and to improve eco-friendliness of the reinforced concrete (RC) structure. This paper experimentally investigated the effective depth of the section and the spacing of strands in the weft and warp direction on the flexural behavior of textile reinforced concrete (TRC) slabs applied the biaxial warp knitting structure grid-type CFRP reinforcement (hereafter referred to as carbon grid) with the narrow spacing of strands. As a result, it was found that the maximum load increased and the deflection at peak decreased as the effective depth increased. In addition, when the strand spacing was narrow, the load was gradually reduced as the load was transferred to the carbon grid after the peak. On the other hand, compared with the RC specimens, the stiffness of the TRC specimens was sharply lowered due to cracks, resulting in greater deflection at the same load. Although the maximum loads of the TRC specimens were larger than those of the RC specimens, the TRC specimens exhibited brittle behavior due to strand fracture after the peak. In this paper, based on the experimental results, the load-deflection relationship of the TRC structure was modeled as a bilinear curve in which the stiffness changes around the crack initiation point, and to calculate the stiffness after crack initiation, an equation that applied a reduction factor to the cracked transformed moment of inertia was proposed. The stiffness after cracking according to the proposed formula was larger than that to the experimental results, but the overall load-deflection relationship was shown to be able to be simulated.

Static analysis of a radially retractable hybrid grid shell in the closed position

Jianguo Cai,Chao Jiang,Xiaowei Deng,Jianfeng Zhao,Yixiang Xu 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.6

A radially retractable roof structure based on the concept of the hybrid grid shell is proposed in this paper. The single-layer steel trusses of the radially foldable bar structure are diagonally stiffened by cables, which leads to a single-layer lattice shell with triangular mesh. Then comparison between the static behavior between the retractable hybrid grid shell and the corresponding foldable bar shell with quadrangular mesh is discussed. Moreover, the effects of different structural parameters, such as the rise-to-span ratio, the bar cross section area and the pre-stress of the cables, on the structural behaviors are investigated. The results show that prestressed cables can strengthen the foldable bar shell with quadrangular mesh. Higher structural stiffness is anticipated by introducing cables into the hybrid system. When the rise-span ratio is equal to 0.2, where the joint displacement reaches the minimal value, the structure shape of the hyrbid grid shell approaches the reasonable arch axis. The increase of the section of steel bars contributes a lot to the integrity stiffness of the structure. Increasing cable sections would enhance the structure stiffness, but it contributes little to axial forces in structural members. And the level of cable prestress has slight influence on the joint displacements and member forces.

Construction Process Analysis for a Single-Layer Folded Space Grid Structure in Considering Time-Dependent Effect

Zhen Zhou,Jing Wu,Shao-ping Meng,Qi Yu 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.2

A new long-span space grid structure system, “single-layer folded space grid” (SFSG), is applied in the Shenzhen Universiade Stadium. Compared with regular single-layer grid, the out-of plane stiffness and bearing capacity of the structure is improved with bending and uplifting of the structural units in SFSG, and the span capacity of the structure is then enhanced. Because of the large structural dimension, the construction process including assembling, closure and brace-unloading should be divided into many stages. As a result, there is very strong time-dependent effect for the structural stress state in construction. In this paper, based on matrix mechanics model of space grid structures, a time-dependent analysis method considering temperature variation during construction is presented based on matrix mechanics model to optimize the closure scheme. A combined brace element is presented to accurately simulate the mechanic character of temporary braces. In this way, the whole construction process of assembling, closure and brace-unloading are effectively and accurately analyzed for the SFSG structure of Shenzhen Universiade Stadium. The displacement state, stress distribution, and force changes in temporary braces are obtained to provide instruction for the design and control of construction process.

An Analysis of the Hierarchical-Grid Urban Structure in the Gangnam Area, Seoul

박성용 한국공간디자인학회 2023 한국공간디자인학회논문집 Vol.18 No.2

(Background and Purpose) Owing to rapid economic growth and urban reorganization, the Gangnam area of Seoul was planned with the dual goals of industrialization and national reconstruction. Accordingly, there are conflicting goals for efficiency and habitability in Seoul’s Gangnam area. Reflecting this, the Gangnam area has a unique urban structure that applies a hierarchical road system to a uniform grid urban fabric by fusing Neighborhood Unit Theory into a grid structure. This study aimed to analyze the hierarchy and pedestrian volume of roads in the urban grid structure of Gangnam and to identify the relationship between the two. (Methods) The study was conducted as follows: First, the road hierarchy of the research site was analyzed, revealing the relationship between road hierarchy, street block hierarchy, and land use. Second, radius-3 integration in an urban block in Gangnam was conducted using space syntax. Third, a pedestrian volume survey of the roads in an urban block was conducted. Pedestrian volume measurements were performed for all arteries and collectors inside the studied urban block. Fourth, the relationship between the hierarchy of roads was analyzed in the first and second steps, and the pedestrian volume was analyzed in the third step. (Results) First, as a result of the hierarchy analysis of roads and street blocks at the research site, it was found that the urban role and connectivity of roads increased as they moved to the outskirts of the urban block, showing characteristics of centrifugality. Second, the radius-3 integration analysis using space syntax results showed that road connectivity increased toward the inside of the urban block, showing characteristics of centrality. Third, due to the actual measurement of pedestrian volume, the pedestrian volume of the outer arterial and the back road was high, and the pedestrian volume of the central part of the urban block was found to be the lowest. This finding implies that the results of the actual pedestrian volume measurement are closer to the hierarchy analysis results of roads and street blocks than those of the radius-3 integration analysis. (Conclusion) This study analyzed and demonstrated the hierarchy of roads and street blocks in urban blocks in the Gangnam area of Seoul in various ways. The urban block in Gangnam is a unique urban structure, as it has a grid shape, but at the same time, it has a road hierarchy according to Neighborhood Unit Theory. In other words, because various principles coexist, contradictory results have been found in the urban structure, depending on the type of analysis. This finding suggests that to properly understand the urban structure in Gangnam, it is necessary to cross-verify it using multi-layered analysis tools.

인공위성의 격자보강 복합재 패널 제작용 치공구 설계 기술

서현석,이주훈,장태성,김원석,현범석,김상호,한은수,심은섭 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

전자모듈을 위성체의 구조에 함침 혹은 내장 시키는 본 연구의 다기능 구조체(Multi-Functional Structure)의 주요 기술은 사각형 격자보강 구조체이다. 그러나, 격자강화 패널의 제작을 위해서는 프리프레그 적층과 오토클레이브 경화를 위한 특별한 치공구가 필요하다. 치공구 설계는 사용될 치공구의 재료, 오토클레이브 성형 시의 온도 변화에 따른 각각 다른 치공구 재료의 열 팽창률을 감안하여 이루어진다. 본 논문에서는 격자강화 구조체의 제작을 위한 치공구 설계 기술을 제안하며, 설계된 제작용 치공구를 검증하기 위하여, 실제 복합재 시제 패널 제작 전에, 축소형 복합재 시제 패널을 제작 하였다. As the key technology for Multi-Functional Structure, which folds the electronics into the walls of the spacecraft, of this study, the rectangular grid-stiffened composite structure has to be achieved properly. However, the grid-stiffened composite panel can be produced using the special manufacturing tools for the prepreg lay-up and autoclave curing process. To prepare the manufacturing tools, the thermal expansion due to the high temperature gradient during the autoclave curing has to be considered. This paper suggests the manufacturing tool design for the grid-stiffened composite structure. And, to verify the tool design for the real grid-stiffened composite panel, the reduced grid-stiffened composite panel was manufactured.

위성용 다기능 구조체의 격자강화 복합재 패널 제작 기술

서현석,이주훈,장태성,김원석,현범석,김상호,한은수,심은섭 한국항공우주학회 2011 한국항공우주학회 학술발표회 논문집 Vol.2011 No.11

최근의 인공위성 설계는 부피 및 무게가 작도록 개발되고 있으며, 부피/무게를 절감하기 위한 위성 설계의 새로운 개념으로 전자, 열제어, 방사차폐 및 구조를 일체화 시킨 다기능 구조체(Multi-Functional Structure)가 개발되고 있다. 본 연구의 다기능 구조체의 구조물은 사각형 격자강화 복합재 패널이며, 격자강화 복합재 패널의 제작 공정은 매우 복잡하다. 본 논문에서는 격자강화 복합재 패널의 제작을 위해, 오토클레이브 성형 방법을 활용한 새로운 적층 및 제작 공정을 제안한다. In recent years, the trends of the spacecraft design have been towards smaller and lighter. In order to reduce the volume/weight of the satellite, the multi-functional structure, which integrates the electronics, thermal control, radiation shielding and structure, as a new concept for the spacecraft design has been developed. The structure of the multi-functional structure of this study is a rectangular grid-stiffened composite panel. However, the manufacturing process of the grid-stiffened composite panel is complicated. This paper suggests the new stacking and manufacturing process using the autoclave curing methodology for the grid-stiffened composite panel.