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섬유방향 예측이론을 적용한 탄소나노튜브 보강 알루미늄 복합재의 분자동역학 해석
박동문(Dong mun Park),이승준(Seung jun Lee),윤길호(Gil ho Yoon) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
This research presents Molecular Dynamics (MD) simulations to characterize the tensile behaviors of aluminum (Al) composites reinforced with carbon nanotubes (CNTs) considering the relative positions and alignments of CNTs. The positions, alignments and condensations of CNT inside aluminum composites are usually stochastic in real and obviously, they influence the tensile behaviors of the composites. Therefore, it is important to quantize the strengths of the CNT-Al composites depending on the configurations of CNTs. To find out the effects of the configurations of CNTs, a computational approach based on MD simulations is used to analyze the mechanical behavior of the CNT-Al composite material under tensile tests. The angle of the CNTs is varied inside an aluminum composite to estimate the Yield strengths of the composites applying MD simulations. Compared with the strength of pure Al composite, the Young’s modulus of an aluminum composite increases about 20 GPa from 71.52 GPa to 92 GPa (Chiral vector (6,6), 0 degrees). However, when inclined carbon nanotubes are inserted to make a composite, the strength is deteriorated due to the interface slip and the necking of Al block. It is also observed that both yield stress and yield strain are deteriorated. This deterioration is mostly due to premature failure of the CNT–Al composite due to CNT local buckling.
박민재(Minjae Park),김대경(Dae-Kyung Kim),김종운(Jong-Woon Kim),박동호(Dong Ho Park),박병노(Byoung-Noh Park),박종훈(Jong Hun Park),송미옥(Mi-Ok Song),성시일(Si-Il Sung),정기문(Ki Mun Jung),임재학(Jae-Hak Lim) 한국신뢰성학회 2021 신뢰성응용연구 Vol.21 No.3
Purpose: We developed a multicriteria decision model to assist decision-makers in determining the optimal inspection intervals based on a set of competing criteria, such as cost, downtime, and availability. Methods: A procedure based on multiattribute utility theory is proposed for developing the model. The proposed approach can simultaneously determine the optimal inspection intervals for monitoring the failure behavior of systems trails to be inspected, maintainability features, and decision-maker preferences for cost, downtime, and availability. Results: We determined the optimal inspection intervals for periodic condition monitoring based on delay time analysis and a multicriteria framework. Conclusion: We developed a multicriteria decision model that includes cost, downtime, and availability for consequences that have multiple dimensions to be considered.
최형규(Hyunggyu Choi),이종욱(Jong Wook Lee),박동문(Dong mun Park),오동현(Dong Hyeon Oh),윤길호(Gil Ho Yoon) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Generally, the bullet is fired with rotation by the rifling. The rotation of the bullet helps the bullet’s linear motion and affects the tumbling phenomenon occurring inside the human body. In this study, we investigated how the rotation of the bullet due to the rifling affects the inside of the human body. To analyze the behavior, 10% of gelatin block was used, and the experiment was performed by changing the shape of the bullet and the impact energy of the bullet. Bullet without rifling used high-speed launch device using air pressure, and the bullet with rifling proceeded at Poongsan. The difference of the steel wire was analyzed through the bullet experiment.