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딥드로잉 공정에서 공정변수에 따른 CR340/CFRP 복합재료의 에폭시 거동과 성형성평가
이민식(M. S. Lee),김성진(S. J. Kim),김현호(H. H. Kim),강충길(C. G. Kang) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.10
Recently, in automotive industry, there has been increasing demand for environment friendly materials for light-weight of vehicles to improve their safety and fuel efficiency and reduce environmental contamination. On the other hand, the weights of these types of vehicles have increased because of additional electronic devices, such as motors or batteries. To resolve these issues, it is necessary to develop parts for vehicles with good specific strength and specific stiffness. In this study, a hybrid composite material was fabricated by stacking CFRP on CR340 plates to increase the specific strength and specific stiffness instead of thick boron steel plates or DP steels, which have been used as reinforcing materials to improve the fracture toughness of the center pillar among vehicle parts.
Boron alloy sheet/CFRP 복합소재의 접착특성 및 기계적특성 연구
이민식(M. S. Lee),김현호(H.H. Kim),강충길(C. G. Kang) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Light weight vehicle has been required more and more in order to Increase fuel efficiency and to reduce CO² that cause global warming. The demands has been developed advanced composite materials such as aluminum, magnesium alloys and CFRP(Carbon fiber reinforced plastic). The advanced composite materials are being developed and used in the various industries such as automobile, aerospace, high-speed train and other construction. Recent, Al/CFRP or steel/CFRP hybrid materials have investigated to apply this material in automobile industry. It is essential that lower time and lower cost fabricating should be followed first. In this study, Hot-press molding method is used to reduce time and cost. Boron steel/CFRP was made by hot-press molding in temp 140℃ and 0.4㎫. This method is faster 8 times than autoclave. But hot press molding method needs hybrid materials that have good bonding strength and mechanical properties. After boron steel/CFRP hybrid materials were made by hot press molding, bonding strength and mechanical properties were investigated through 3-point bending test, simple tensile test and shear test. Coated and uncoated boron steel sheet were used to know how coating affect bonding strength. In the shear and T-peel test, uncoated boron steel/CFRP hybrid materials became better than coated boron steel/CFRP.
이민식(M. S. Lee),문정환(J. W. Moon),서판기,하세윤,강충길(C. G. Kang) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
Recently in the automobile industry, there have been several efforts to reduce the weight and enhance the safety of vehicles. In this study, the hardable boron steel sheet was used in hot press deep drawing process. Through hot press deep drawing, boron steel sheet alloys generally show a good formability, work hardening and a small amount of spring back. The main process parameters are punch speed, blank holding force and initial blank temperature. Experiments were performed at a constant temperature for the die and punch. The effects of the main process parameters were thoroughly investigated. After forming process, two main kinds of graphs were obtained; (1) the graphs presenting relationship between punch load, blank holding force and forming depth and (2) the graphs presenting relationship between blank holding force, punch velocity and forming depth. Finally, the corresponding maximum punch load and maximum forming depth value were obtained for forming depth limited. Then regions of fracture and non-fracture were made with point in graph. Furthermore, the microstructural observations and hardness were conducted for different part of the formed boron steel sheets after die quenching.
보론강의 열간 딥드로잉시 공정변수에 따른 소재의 변형거동해석
이민식(M. S. Lee),백승철(S.C. Back),강충길(C. G Kang) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Recently in the automobile industry, there have been several efforts to reduce the weight and enhance the safety of vehicles. In this study, the hardable boron steel sheet was used in hot press deep drawing process. Through hot press deep drawing, boron steel sheet alloys generally show a good formability, work hardening and a small amount of spring back. The main process parameters are punch speed, blank holding force and initial blank temperature. Experiments were performed at a constant temperature for the die and punch. The effects of the main process parameters were thoroughly investigated. After forming process, two main kinds of graphs were obtained ; (1) the graphs presenting relationship between punch load, blank holding force and forming depth and (2) the graphs presenting relationship between blank holding force, punch velocity and forming depth . Finally, the corresponding maximum punch load and maximum forming depth value were obtained for forming depth limited. Then regions of fracture and non-fracture were made with point in graph. Furthermore, the microstructural observations and hardness were conducted for different part of the formed boron steel sheets after die quenching.
딥드로잉 공정에서 공정변수에 따른 적층순서가 다른 CR340/CFRP 복합재료의 에폭시 거동과 성형성평가
이민식(M. S. Lee),최수원(S. W. Choi),강충길(C. G. Kang) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.10
Recently, in automotive industry, there has been increasing demand for environment friendly materials for light-weight of vehicles to improve their safety and fuel efficiency and reduce environmental contamination. On the other hand, the weights of these types of vehicles have increased because of additional electronic devices, such as motors or batteries. To resolve these issues, it is necessary to develop parts for vehicles with good specific strength and specific stiffness. In this study, a hybrid composite material was fabricated by stacking CFRP on CR340 plates to increase the specific strength and specific stiffness instead of thick boron steel plates or DP steels, which have been used as reinforcing materials to improve the fracture toughness of the center pillar among vehicle parts.