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알루미늄 합금으로 된 경사진 이중외팔보의 충돌에 대한 실험 및 해석
고등 ( Teng Gao ),조재웅 ( J U Cho ),전성식 ( Seong S Cheon ) 한국복합재료학회 2014 Composites research Vol.27 No.2
본 연구에서는 알루미늄 합금으로 된 경사진 이중외팔보의 충돌에 대해서 각각의 충격속도 2.5m/s, 7.5m/s, 12.5 m/s 별로 실험과 시뮬레이션 해석을 하였다. 접착부분에 발생하는 에너지 해방율과 응력을 평가하여 알루미늄 합금의 기계적 특성을 고찰하였다. 실험상에서는 접착 부분에서 에너지 해방율의 값이 높은 것으로 나타났다. 이는 실험에서 시험편이 분리된 후에도 접착력이 유지되는 특성 때문인 것으로 사료된다. 충격속도와 상관없이 균열이 진전하다가 접착된 부분의 끝에서 높은 응력을 발생하기 때문에 최대 등가응력은 마지막 단계에서는 올라간다. 본 연구에서의 실험 및 해석결과들은 충돌에 의한 균열 진전을 방지할 수 있는 복합재료에 대한 안전설계의 개발에 필요한 자료로 사료된다. This study is investigated by experiments and analyses at rates of 2.5m/s, 7.5m/s and 12.5m/s on the impact of tapered double cantilever beam specimens with aluminium alloy. It aims to examine the mechanical property of aluminum alloy by evaluating energy release rate and equivalent stress happened at the bonded part of specimen. Because bonding force remains after the separation of specimen, the energy release rate at the bonded part becomes highest. As crack propagates and the high stress happens at the end of the bonded part, the maximum equivalent stress becomes higher at the last stage, regardless of impact rate. These results of experiments and analyses are the data necessary to develop the safe design of composite material to prevent crack propagation due to impact.
접착제로 접합된 경사진 이중외팔보의 충돌에 대한 시뮬레이션 해석 및 검증
고등,조재웅 한국기계기술학회 2013 한국기계기술학회지 Vol.15 No.5
Tapered double cantilever beam (TDCB) specimens are the most commonly used test configurations to measure the fracture toughness of composites and adhesive joints. The material used in this study is aluminum alloy. For the impact analysis, load and displacement applied from pin onto end block as well as the crack energy release rate are calculated and compared with the finite element analysis results. The energy release rate increases with the velocity increases. As TDCB model with the same condition as experiment is simulated and analyzed, the fracture behavior can be estimated with the analysis result similar to experiment. The simulation results can be agreed with experimental graph and all experimental data at this study can be verified. These experimental results can be applied into real field effectively. It is found that the energy release rates measured from impact tests on the specimens can be predicted by the finite element model suggested in this study.
면내 및 면외 하중 조건들에 따른 이종 복합 소재를 가진 경사진 이중외팔보에서의 접착계면의 파괴 특성 연구
이정호 ( Jung-ho Lee ),김재원 ( Jae-won Kim ),전성식 ( Seong-sik Cheon ),조재웅 ( Jae-ung Cho ) 한국복합재료학회 2020 Composites research Vol.33 No.6
공학 및 산업 분야에서는 구조적인 부분들에서 경량 복합 소재가 강과 같은 금속 소재를 대체해 오고 있다. 이러한 복합 소재는 리벳, 용접이나 볼트 및 너트를 이용한 체결 방법을 대신하여 접착제 체결 방법을 적용하고 있다. 복합 소재에 접착제 체결 방법을 적용하기 위해서는 접착계면에 대한 강도 특성 연구가 필수적으로 요구된다. 섬유 강화 플라스틱 복합 소재인 CFRP를 용이하게 가공하여 본 연구를 수행하였다. CFRP와 알루미늄(Al6061), 알루미늄 폼(Al-foam)을 가진 이종 복합 소재로 된 경사진 이중외팔보(TDCB) 시험편들로서 면내 전단과 면외 전단의 하중 조건들하에서 정적 실험을 수행하였다. 본 연구 결과를 통하여 이중외팔보들의 파괴 특성과 그 파단 시점을 파악하여 접착계면을 가진 이종 복합 소재 구조물에 관한 내구성을 검토하였다. At the engineering and industrial areas, the lightweight composite material has been substituted with the metals, such as steel at the structural parts. This composite material has been applied by the adhesive bonding method, as well as the joint methods with rivets, welds or bolts and nuts. The study on the strength characteristics of adhesive interface is necessarily required in order to apply the method to composite materials. CFRP specimens as the fiber reinforced plastic composites were manufactured easily and this study was carried out. The static experiments were performed under the loading conditions of in-plane and out-plane shears with the inhomogeneous composite TDCB specimens with CFRP, aluminum (Al6061), and aluminum foam (Al-foam). Through the result of this study, the durability on the inhomogeneous composite structure with adhesive interface was investigated by examining the fracture characteristic and the point in time.
Jae-Won Kim(김재원),Jae-Ung Cho(조재웅) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.3
The fracture characteristic of the bonded interface under the application of a sliding load to a double cantilevered specimen manufactured using lightweight material was examined. Inhomogeneously bonded materials such as Al6061-T6, CFRP, and CFRP-Al were employed. In the experiment, the specimen was loaded on both directions by applying a shearing load to the bonding interface. The experimentally obtained stress, specific strength and energy release rate values were examined. CFRP exhibited excellent specific strength. The experimental results demonstrated that the inhomogeneous bonded material CFRP-Al exhibited an overall high performance in comparison with the single materials.
방혜진(Hye-jin Bang),이상교(Sang-kyo Lee),조종두(Chongdu Cho),조재웅(Jae-ung Cho),최해규(Hae-kyu Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Aluminum foam has developed in many commercial fields, especially transport machines division as a kind of porous metal. In this paper, Aluminum foam with the initial crack and closed cell form is used to take the axial load-time graph. It is fabricated with adhesively bonded DCB (Double Cantilever Beam) form and accordance with BS (British Standard) and ISO international standard. Using 10 kN Landmarks of MTS Corporation, 15 ㎜/min velocity of mode I shape is applied to aluminum foam specimen with displacement control method. And ABAQUS 6.10 is used to model and analyze the same model as a three dimension with same condition of experiment. Based on the result of axial load-displacement graph of experiment and image of that included of crack length depended on the time, energy release rate will be calculated and then the model is analyzed with this fracture energy condition. As a result, it is shown that different force aspect according to the displacement value and there is not big deformation in aluminum foam while Double Cantilever Beam get the force due to aluminum foam has bigger density and modulus than adhesive. Also, the similar maximum value is calculated using finite element method of cohesive element comparing with experiment.
초고장력강과 Mg 합금강으로 된 모드-II 이중외팔보 시험편의 형상에 따른 파괴 특성에 관한 연구
나우석,조재웅 한국기계기술학회 2020 한국기계기술학회지 Vol.22 No.2
This study aims at investigating the fracture characteristic according to the shape of the double cantilever beam specimen for mode II with ultra-high strength steel and Mg alloy steel. As the analysis, all three models had the left-hand holes that were constrained by the cylindrical support and the right-hand holes were enforced by the constraint condition of 6mm/min. This study result showed that the shorter the load block of the double envelope test specimen, the higher the safety. The results of this study are thought to be useful for examining the fracture characteristics of specimen for mode II with ultra high strength steel and Mg alloy steel.