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횡방향 하중을 받는 CFRF 적층복합재의 내부손상에 관한 연구
김문생,박승범,오득창,Kim, Moon-Saeng,Park, Seung-Bum,Oh, Deug-Chang 한국정밀공학회 1995 한국정밀공학회지 Vol.12 No.11
An investigation was performed to study the inner damage of laminated composite plates subjected to out-of-plane load. During the investigation, inpact velocity and equivalent static load relationship was derived. Reddy's higher-order shear deformation theory(HSDT) and Hashin's failure criteria were used to determine inner stresses and damaged area. And impact testing was carried out on laminated composite plates by air gun type impact testing machine. The CFRP specimens were composed of [ .+-. 45 .deg. ]$_{4}$and [ .+-. 45 .deg. /0 .deg. /90 .deg. ]$_{2}$ stacking sequences with 0.75$^{t}$ * 26$^{w}$ * 100$^{l}$ (mm) dimension. After impact testing. As a result, a relationship holds between damaged area and impact energy, and a matrix cracking was caused by the interlaminar shear stress in the middle ply and was caused by the inplane transverse stress in the bottom ply.
볼 충격을 받는 유리의 콘크랙형성에 대한 경계조건의 영향
김문생,허진,이현철,김호종,Kim, Moon-Saeng,Heo, Jin,Lee, Hyeon-Chul,Kim, Ho-Jong 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.6
In order to investigate the possibility of processing of brittle material by ball impact, the effects of boundary conditions about impact damage of soda-lime glass by small spheres were evaluated experimentally. It was investigated that crack appearance developed in soda-lime glass with boundary conditions of without sealing, single-sealing and double-sealing by impact velocity. The double-sealing was most effective in the development of perfect cone than other boundary condition. In case of double-sealing condition, PVC and Polyurethane sealing were more effective in producing a perfect cone formation than other sealing materials. The impact velocity range over which perfect cones were formed was influenced by both the contact area and diameter of impact particle.
적층복합판의 충격에 의한 모재균열 및 층간분리에 관한 연구
김문생,박승범,Kim, Moon-Saeng,Park, Seung-Bum 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.2
An investigation was performed to study the matrix cracking and delamination in laminated composite plates due to transverse impact. A model was developed for predicting the initiation of the matrix cracking and the shape and size of impact-induced delamination in laminated composite plates resulting from the ballistic impact. The model consists of a stress analysis and a failure analysis. A transient finite element analysis which was based on the higher-order shear deformation theory was adopted for calculating the stresses inside the laminated composite plates during impact. A failure analysis was used to predict the initial intraply matrix cracking and the shape and size of the interface delamination in the laminates. As a results, a shear matrix cracking which was governed by the transverse interlaminar shear stress occured at the middle layer near the midplane of laminates and a bending matrix cracking which was governed by the transverse inplane stress occured at the bottom layer near the surface of laminates. In a thick laminates, a shear matrix cracking generated first at the middle layer of laminates, but in a thin laminates, a bending matrix cracking generated first at the bottom layer of laminates.
충격하중을 받는 금속복합재료의 동적변형거동에 관한 연구
김문생,이현철,Kim, Moon-Saeng,Lee, Hyeon-Chul 대한기계학회 1993 대한기계학회논문집 Vol.17 No.7
The characteristics of metal matrix composite under dynamic tension at high strain rates up to the order of $10^3/sec$ is studied by using newly developed apparatus. The composite material processed in this research is aluminum-alumina metal matrix composites, arid fabricated by compocasting with the fiber volume fraction from 5 to 20%. The whisker and matrix material used in this paper were ${\delta}-Al_2O_3$ and Al-6061, respectively. The mechanical tests performed in this research are low and high strain rate tensile test. At low strain-rate tensile test, the modulus of elasticity and the ultimate tensile strength of the composites were improved about 77 pct. and 55 pct., respectively comparing with the unreinforced materials. At strain-rate from $10^{-3}\;to\;10^3/s$, the effect of strain-rate on the modulus, ultimate strength, flow stress is determined. Also the effect of strain rate on the modulus, ultimate tensile strength, flow stress and elongation to failures were investigated.
충격하중을 받는 유리의 콘크랙형성에 대한 경계조건의 영향
김문생(Moon Saeng Kim),허진(Jin Heo) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.4
In order to investigate the possibility of processing of brittle material by ball impact, the effects of boundary conditions about impact damage of soda-lime glass by small spheres were evaluated experimentally. It was investigated that crack appearance developed in soda-lime glass with boundary conditions of without sealing, single sealing and double sealing by impact velocity. The double sealing in the development of perfect cone were most effective than other boundary conditions. In case of double sealing condition, PVC sealing was more effective in producing perfect cone cracks than Al, PU sealing. Also the impact velocity of the formation of the cone crack was influenced by contact area and maximum dynamic load.
강구에 의한 횡방향 충격을 받는 적층복합판의 충격 응답 거동
김문생(Moon-Saeng Kim),김남식(Nam-Shik Kim),박승법(Seung-Bum Park),백인환(In-Hwan Paik) 한국해양공학회 1993 韓國海洋工學會誌 Vol.7 No.2
본 연구는 강구에 의한 충격을 받는 유리/에폭시 적층복합판의 충격 응답 및 파동 전파 특성을 연구하는데 그 목적이 있다. 이를 위하여 고차전단변형이론에 기초한 동적 유한요소해석을 행하였으며, 저속 및 고속 충격 실험을 행하였다. 동적 유한요소해석으로 부터 접촉력의 변화와 강구의 반발 속도 그리고 충격에 의한 변형률 응답을 구하였다. 변형률 응답은 충격 실험의 결과와 비교하였다. 또한 고속 충격 실험의 결과로 부터 파동전파 속도를 계산하여 파동 전파 이론에 의한 결과와 비교 검토하였다.<br/> 그 결과, 충격 실험에서 구한 변형률 응답은 동적 유한요소해석에 의한 결과의 경향과 잘 일치하였으며, 충격 속도의 증가에 따른 최대접촉력의 증가율은 판의 크기가 클수록 증가하였다. 그리고 파동 전파 속도는 두 결과가 잘 일치하였으며, 접촉시간에 의한 영향으로 강구의 크기가 클 수록 빠르게 나타났다. The purpose of this paper is to analyze the impact response behaviors of glass/epoxy laminated composite plates subjected to the transversely impact of a steel ball. For this purpose, dynamic finite element analysis based on the higher-order shear defomation plate theory is used to compute the contact forces, rebound velocity of a steel ball, and dynamic strain response histories. And low-velocity and high-velocity impact experiments were conducted to compare the results and compute the wave propagation velocities.<br/> The results obtained from impact experiments are in good agreement with those of dynamic finite element analysis. Also the wave propagation velocities obtained from high-velocity impact experiments and wave propagation theory agree well, and wave velocities were higher in the smaller radius of steel ball.