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염수환경에 의한 UPN139 탄소/에폭시 복합재 물성치 변화 연구
김중진(Joong-Jin Kim),문철진(Cheol-Jin Moon),허성화(Seong-Hwa Hur),이청락(Cheng-Rak Lee),권진회(Jin-Hwe Kweon),최진호(Jin-Ho Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
Experiments were performed to investigate the effect of salt water on the mechanical properties of UPN-139 carbon-epoxy composite after 0, 1, 3, 6, 9 and 12 months immersion in 3.5% salt water. Waterproof painting and sealing tape were applied to protect the water absorption on the both cutting sides and taps of specimens. Test results show that while the tensile properties in fiber and matrix direction did not decrease considerably until 12 months of immersion, shear strength and modulus decreased gradually from nine months of the immersion. The reduction of shear strength and modulus were 9.5% and 10.8% of the values of dry specimens without exposure to salt water, respectively .
피복관 프레팅마모 해석을 위한 LuGre 마찰모델 성능 고찰
박남규(Nam-Gyu Park),김진선(Jin-Seon Kim),김중진(Joong-Jin Kim),김재익(Jae-Ik Kim) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10
Friction between the fuel cladding tube and the grid supports causes fretting wear, and it degrades fuel performance. LuGre friction model is introduced in the paper, and the performance was evaluated comparing to the classical Coulomb model. The Coulomb friction model is widely used, but this paper discussed that Coulomb friction could not provide reasonable results. Stick-slip, which is most critical to fretting wear, cannot be realized. It is shown that the developed friction force in the Coulomb model is not enough to resist or delay the system motion. On the other hand, the stick-slip can be simulated using LueGre friction model. Two dimensional spacer grid cell model with LuGre friction is also reviewed, and it is discussed that the new friction model simulates well the nonlinear mechanism.