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횡방향 전단하중을 받는 단일방향 복합재료의 미시역학적 거동연구
최흥섭,Choi, Heung-Soap,Achenbach, J.D. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.11
Effects of fiber-matrix interphases on the micro-and macro-mechanical behaviors of unidirectionally fiber-reinforced composites subjected to transverse shear loading at remote distance have been studied. The interphases between fibers and matrix have been modeled by the spring-layer which accounts for continuity of tractions, but allows radial and circumferential displacement jumps across the interphase that are linearly related to the normal and tangential tractions. Numerical calculations for basic cells of the composites have been carried out using the boundary element method. For an undamaged composite the micro-level stresses at the matrix side of the interphase and effective shear stiffness have been computed as functions of fiber volume ratio $V_f$ and interphase stiffness k. Results are presented for various interphase stiffnesses from the perfect bonding to the case of total debonding. For a square array composite the results show that for a high interphase stiffness k>10, an increase of $V_f$ increases the effective transverse shear modulus G over bar of the composite. For a relatively low interphase stiffness k<1, it is shwon that an increase of $V_f$ slightly decreases the effective transverse shear modulus. For the perfect bonding case, G over bar for a hexagonal array composite is slightly larger than that for a square array composite. Also for a damaged composite partially debonded at the interphase, local stress fields and effective shear modulus are calculated and a decrease in G over bar has been observed.
최흥섭(Heung Soap Choi),노희석(Hee Seok Roh),장용훈(Yong Hoon Jang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
In this study, analytic stress-displacement solutions are obtained by using a shear lag modeling constructed<br/> for the spliced joint area with a splicing gap filled with adhesive material of elastic modulus Ea in the fiber<br/> metal laminate (FML) which is known to have excellent fatigue, corrosion and fire-flame resistant<br/> characteristics while with relatively low densities compared to the conventional aluminum alloys for<br/> lightweight structures.
최흥섭(Heung Soap Choi),Roman Lanz,전흥재(Heoung Jae Chun) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
This study compares quantitatively and qualitatively the ability of several different repair methods for the advanced composite sandwich structures, to reacquire the pre-damage mechanical properties. The results of this work may be used in the repair of honeycomb sandwich panel structures as used in the spoilers, rudder and floor panels of aircraft. The evaluation tests performed on the Nomex honeycomb sandwich panel with a graphite/epoxy skin include measuring initial mechanical properties by the 4 point bending test and edgewise compression test, and comparing them with the results obtained for damaged and repaired specimens. The damage types studied will be low energy impact, delamination, skin hole and penetrating holes on sandwich panel. One/two-sided cocured, precured skin patches and core replacement will be used in the repair assessment.
최흥섭(Heung Soap Choi),조윤호(Younho Cho) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.1
After the advent of B787(Boeing Co.), a civil aircraft using composite materials more than 50% of it total structural weight for weight savings, best performances and efficiencies, various endeavors to develop and apply the state of art of structural health monitoring(SHM) technologies for composite aircraft have been made for many years. Despite their plentiful advantages composite aircraft structures are susceptible to the hidden or barely visible impact damages(BVID) and excessive loads that if unchecked may lead to lower structural integrity, loss of operational performance and finally a sudden catastrophic failure of the aircraft structure. In this paper background of SHM technology and relevant technologies for application of SHM technology to the composite aircraft in the near future and requirements for certification of SHM system are shortly presented.
해양레저 분야 복합소재 적용: 33피트급 아메리카스컵 훈련용 CFRP 세일링 요트 개발
서형석 ( Hyoung Seock Seo ),장호윤 ( Ho Yun Jang ),이인원 ( In Won Lee ),최흥섭 ( Heung Soap Choi ) 한국복합재료학회 2015 Composites research Vol.28 No.1
본 논문에서는 해양레저분야에서의 현재 복합재 적용 현황과 33피트급 아메리카스컵 훈련용 세일링 요트 개발에 대해 기술한다. 항공분야와 달리 해양레저 분야에서의 복합재료는 최근에서야 적용 및 사용이 되기 시작했다. 다양한 해양레저 구조물 중에서도 특히, 아메리카스컵 세일링 경주 요트는 빠른 속도를 내야 하기 때문에 경량화 및 높은 기계적 성능이 요구되고 이에 따라 경주용 요트를 건조함에 있어 탄소섬유의 사용은 필수적이다. 탄소섬유강화 플라스틱 경주용 요트 제작 과정을 정립하기 위해 탄소 돛대와 탄소 요트 선체에 대한 최적화 설계와 생산 공법에 대해 논의되었다. 최종적으로 이렇게 제작된 탄소섬유강화복합재 세일링 요트는 운항시험을 통해 경주용 요트로써의 높은 성능을 보여주었다. The purpose of this paper is to investigate the current trends of composite applications in the marine and leisure fields and to study the development of 33ft class America’s cup training CFRP sailing yacht. In the field of marine and leisure, composite materials have been just used to marine and leisure structures, recently. Especially, since the America’s cup of sailing yacht racing has required the light weight and high mechanical performance to make a high speed, CFRP have been recognized as the critical material to construct the racing yacht structures. To establish the process of CFRP racing yacht construction, the design optimizations and production methods of carbon mast and CFRP yacht hull were discussed in this paper. Finally, the constructed CFRP sailing yacht exhibited high performance as the racing yacht through the sailing test.