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박우림,김송미,권오헌 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5
Type III vessels are used to store gases at high pressure and, for efficient use, should be as light as possible without compromising stability. However, since the fiber composite layer has a directional property, it causes different properties depending on the order of lamination and the direction of the layer, and it is necessary to evaluate various and complex variables because both the low and high lamination angles are used in the manufacturing process. Therefore, this study evaluated the composite material layer of type III high pressure storage vessels in a single layer pattern and a composite pattern, and evaluated the effects of the inherent characteristics of each angle and the increase or decrease in the stacking angle on the strength performance of the storage vessel. As a result of analysis, it was confirmed that the change of angle not only affects the strength performance, but also affects the location of storage vessel such as domes and cylinders. In addition, in the most optimized pattern, the stress of 79 MPa in the fiber direction and 20.35 MPa in the fiber orthogonal direction could be reduced.
박우림,Nurul Fajriyah Fatoni,권오헌 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5
To facilitate the widespread use of fuel cell vehicles, it is necessary to ensure the safety of high-pressure hydrogen storage vessels. Because the composite layer experiences the highest internal pressure, cracks in the carbon fiber reinforced plastic (CFRP) layer of type III high-pressure vessels directly affect their safety. In this study, we evaluate the crack behavior in a type III high-pressure hydrogen vessel using a ply modeling method and the extended finite element method. The failure criteria were determined from the maximum principal stress and displacement that exceed the allowable tensile strength, considering the fiber and the transverse directions of each ply. The weak point of the CFRP composite layers was in the transverse direction on the 17th ply at a helical winding angle of 35° in the boundary of the dome and the cylinder. The crack extension was resulted from exceeding the allowable transverse stress at 35° winding angle. These results may be valuable for ensuring the safety of high-pressure hydrogen vessels.
수소고압저장용기용 팔라듐 첨가 탄소섬유복합재에 대한 멀티스케일 응력해석
박우림,권오헌,Park, Woo Rim,Kwon, Oh Heon 한국안전학회 2018 한국안전학회지 Vol.33 No.2
The multi-scale analysis is more proper and precise for composite materials because of considering the individual microscopic structure and properties of each material for composite materials. The purpose of this study is to verify the validity of using palladium particles in carbon/fiber composites by multi-scale analysis. The palladium is a material for itself to detect leaking hydrogen by using the property of adsorbing hydrogen. The macroscopic model material properties used in this study are homogeneous material properties from microstructure. Homogenized material properties that are calculated from periodic boundary conditions in the microscopic representative volume element model of each macroscopic analysis model. In this study, three macroscopic models were used : carbon fiber/epoxy, carbon fiber/palladium, palladium/epoxy. As a result, adding palladium to carbon/epoxy composite is not a problem in terms of strength.
박우림,전상구,김송미,권오헌 한국안전학회 2019 한국안전학회지 Vol.34 No.5
The type III vessel, which is used to store high-pressure hydrogen gas, is made by wrapping the vessel’s liner with carbon fiber composite materials for strength performance and lightening. The liner seals the internal gas and the composite resists the internal pressure. The properties of the fiber composite material depends on the angle and thickness of the fiber. Thus, engineers should consider these various design variables. However, it significantly increases the design cost due to the trial and error under designing based on experience or experiments. And, for aluminum liners, fatigue loads due to using and charging could give a huge impact on the performance of the structure. However, fatigue failure does not necessarily occur in the position under the highest load in use. Therefore, for hydrogen storage vessel, fatigue evaluation according to design patterns is essential because stress distribution varies depend on composite layer patterns. This study performed an optimization analysis and evaluated a high-pressure hydrogen storage vessel to minimize these trial and error and improve the reliability of the structure, while simultaneously conducting fatigue assessment of all patterns derived from the optimization analysis process. The results of this study are thought to be useful in the strength improvement and life design of composite reinforced high-pressure storage vessels.
확장유한요소법과 멀티스케일 기법을 통한 팔라듐 첨가 탄소섬유/알루미늄 적층구조에 대한 수치해석
박우림,권오헌 한국안전학회 2019 한국안전학회지 Vol.34 No.2
A palladium can adsorb hydrogen and detect leaking hydrogen through changes in color and electrical resistance. This study is to evaluate the structural behavior of carbon fiber adding palladium composite materials used in the hydrogen storage vessel. A multi-scale analysis technique was used to analyze accurately the behavior of each material in relation to the microscopic composition. The multi-scale analysis is more proper and precise for composite materials because of considering the individual microscopic structure and properties of each material for composite materials. Also the crack evaluation was performed by XFEM analysis to confirm the reinforcement performance of aluminum as a liner of the hydrogen vessel. The results show that the addition of the palladium material increased the macroscopic stress, but microscopically the carbon fiber stress was reduced. It means the performance improvement of the palladium added carbon fiber/Al composite.
XFEM을 사용한 TYPE III 수소저장용기의 복합재층 균열거동 해석
박우림(Woo Rim Park),박철준(Cheol Jun Park),전상구(Sang Koo Jeon),권오헌(Oh Heon Kwon) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In order to lead the globalization of fuel cell vehicles, it is necessary to ensure the safety of high pressure hydrogen storage vessel. The cracks in the CFRP layer of the vessel are directly connected the safety of the TYPE III high pressure vessel. The purpose of this study is to evaluate crack behaviors as the weak point of TYPE III high pressure hydrogen vessel by using a ply modeling method and XFEM. The failure criteria was determined by the maximum principal stress and displacement that excess the allowable tensile strength considering fiber and transverse direction of each ply. And the weak point of CFRP composite layers was occurred to the transverse direction at the 17<SUP>th</SUP> and 35° winding ply in the boundary of the dome and cylinder. The crack extension was resulted from of the weak transverse allowable stress at 35° helical winding. The results will be usefully applied to ensure the safety of the high pressure hydrogen vessel.
온도 및 수분이 탄소/아라미드 섬유 복합재의 파손거동에 미치는 영향
권우덕,권오헌,박우림 한국안전학회 2022 한국안전학회지 Vol.37 No.4
This paper presents the effects of high temperature and water absorption on the mechanical behaviors of carbon–aramid fiber composites, specifically their strength, elastic modulus, and fracture. These composites are used in industrial structures because of their high specific strength and toughness. Carbon fiber composites are vulnerable to the impact force of external objects despite their excellent properties. Aramid fibers have high elongation and impact absorption capabilities. Accordingly, a hybrid composite with the complementary properties and capabilities of carbon and aramid fibers is fabricated. However, the exposure of aramid fiber to water or heat typically deteriorates its mechanical properties. In view of this, tensile and flexural tests were conducted on a twill woven carbon–aramid fiber hybrid composite to investigate the effects of high temperature and water absorption. Moreover, a multiscale analysis of the stress behavior of the composite’s microstructure was implemented. The results show that the elastic modulus of composites subjected to high temperature and water absorption treatments decreased by approximately 22% and 34%, respectively, compared with that of the composite under normal conditions. The crack behavior of the composites was well identified under the specimen conditions.