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원통형 복합재료 압력 용기의 기계적 물성 평가를 위한 세그먼트 형링 버스트 시험 방법 분석
김외태 ( Woe Tae Kim ),김성수 ( Seong Soo Kim ) 한국복합재료학회 2021 Composites research Vol.34 No.4
복합재료는 높은 비 강성 및 비 강도 특성으로 인해 기체 혹은 액체 연료를 저장하기 위한 압력 용기의 설계 및 제작에 널리 활용되고 있다. 이에 따라, 압력용기의 파열압력 또는 파단 변형률의 기계적 특성의 보다 정확한 측정은 상용화 전에 필수적 요소이다. 그러나, 기존의 시험방법을 활용한 복합재료 압력 용기의 안전성 검증은 하중 전달 매체의 변형으로 인한 추가적인 에너지 손실의 발생과, 불필요한 하중 및 모멘트의 발생 등의 한계가 있다. 따라서 본 연구에서는 수직기둥의 이론적인 하중전달 정도와 적용 가능한 수직방향 변위를 고려하여 세그먼트형 링 버스트 시험장치를 설계하였다. 또한, 세그먼트 형 링 버스트 시험장치의 균일한 압력분포를 검증하기 위해 수치해석을 활용하였고, 수압 시험방법과 링 시편의 원주방향 응력 및 변형률 분포를 비교하였다. 복합재료 압력용기의 파괴 거동을 모사하기 위해 Hashin 파손 기준을 적용하였고, 실험적으로 파단 변형률을 측정하여 이를 수치해석 결과와 비교하였다. Composite materials have been widely applied for fabricating pressure vessels used for storing gaseous and liquid fuel because of their high specific stiffness and specific strength. Accordingly, the accurate measurement of their mechanical property, particularly the burst pressure or fracture strain, is essential prior to the commercial release. However, verification of the safety of composite pressure vessels using conventional test methods poses some limitations because it may lead to the deformation of the load transferring media or provoke an additional energy loss that cannot be ignored. Therefore, in this study, the segment-type ring burst test device was designed considering the theoretical load transferring ratio and applicable displacement of the vertical column. Moreover, to verifying the uniform distribution of pressure of the segment type ring burst test device, the hoop stress and strain distribution of ring specimens were compared with that of the hydraulic pressure test method via FEM. To conduct a simulation of the fracture behavior of the composite pressure vessel, a Hashin failure criterion was applied to the ring specimen. Furthermore, the fracture strain was also measured from the experiment and compared with that of the result from the FEM.
고압차단기 주조용 AC4CH-T6 합금 외함 파열압력 예측
이희태(Heetae Lee),Ma Ning,Wang Li 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
The gas insulated switchgear(GIS) is a mechanical switching device that connects and breaks current circuit to protect the electric equipment in a power network. To maintain the highest insulation level, main parts of the GIS were placed in the tank with insulating gas under the prescribed design pressure. According to IEC62271-203, it is necessary that tank should have strength to endure the pressure of the proof test which reaches many times of the design pressure to consider rapid increase of the internal pressure and the possible variability of manufacturing process of the tank. For this reason, it is very important to predict the reliable burst pressure of the tank to design the AC4CH-T6 casting aluminum alloy tank of GIS appropriately. In this study, a fracture criterion was proposed to predict the fracture response of the AC4CH-T6 casting aluminum alloy by conducting a series of tests. By using the facture criterion of the AC4CH-T6 and Finite Element Analysis(FEA), the burst pressure of the actual tanks was proposed. Finally, the validity of predicted burst pressure of the tank was evaluated by comparing results from actual hydraulic test of the tank.
이준혁(Jun-Hyuk Lee),조충희(Choong-Hee Joe),김경남(Kyung-Nam Kim),임재규(Jae-Kyu Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
To increase the driving distance of a Natural Gas Vehicle, the high-pressure of fuel-charge is necessary and the development of the device reducing the pressure to suitable pressure for the fuel of high-pressure. So we developed CNG Regulator in this research. The most important performance-index of Regulator is outlet pressure and has to be considered as inlet pressure, the flow of gas and fluid fuel and temperature influence. and it has to be confirmed by the safety for leak, burst and endurance because Regulator is parts that are used by the fuel of high pressure. Also. to know whether the necessary capability of the engine is proved, capability and working experimentation is performed. In result, the capability is proved by the capability of Regulator. Hereafter, we will ensure better capability and safety as more improving the product.
삼축응력 기반의 파괴변형률 기준을 적용한 가우지 손상배관의 건전성 평가
오창균(C. K. Oh),김윤재(Y. J. Kim),박진무(J. M. Park),백종현(J. H. Baek),김영표(Y. P. Kim),김우식(W. S. Kim) 한국정밀공학회 2005 한국정밀공학회 학술발표대회 논문집 Vol.2005 No.10월
Structural integrity assessment of defected pipe is important in fitness for service evaluation and proper engineering assessment is needed to determine whether pipelines are still fit for service. This paper present a failure prediction of gas pipes made of API X65 steel with gouge using stress-modified true fracture strain, which is regarded as a criterion of ductile fracture. For this purpose, API X65 pipes with gouge are simulated using elastic-plastic FE analyses with the proposed ductile failure criterion and the resulting burst pressures are compared with experimental data. Agreements are quite good, which gives confidence in the use of the proposed criteria to defect assessment for gas pipelines. Then, further extensive finite element analyses are performed to obtain the burst pressure solution of pipes with gouge as a function of defect depth, length and pipeline geometry.
삼축응력 기반 파괴변형률 기준을 적용한 박스형 용접구조물의 파열압력 예측
이희태(Heetae Lee),석상민(Sangmin Seok),이재원(Jaewon Lee) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
Despite design precautions to prevent internal arcing in oil-immersed transformers, there is always a residual risk of such an event, with the possibility of a subsequent tank rupture leading on to a fire or an explosion. This paper presents prediction of burst pressure for tanks, box-type welded structures, under internal arcing due to short-circuit failure of transformers. In this study, a stress-modified strain for SM490 steel was proposed as a function of stress triaxiality. To determine the stress-modified fracture strain, tension test of bars with four different notch radii, made of base metal, weldment, and HAZ, is performed. By using the fracture criterion and Finite Element Analysis(FEA), the burst pressure of the actual tank was proposed. Finally, the validity of predicted burst pressure of the tank was evaluated by comparing the result from hydraulic test of the tank.
김욱중(Ook Joong Kim),윤석호(Seok-Ho Yoon),홍용주(Yong Ju Hong),김정엽(Kim Jeong Yup),강신일(Sin-Il Kang) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
Fluid flow and structural analyses of an electronic expansion valve (EEV) using CO2 as a working refrigerant are carried out to estimate the mass flow rate and maximum stress. An engineering sample EEV that the orifice diameter is 1.8 mm was fabricated. The mass flow rates were measured at various EEV inlet temperatures and pressures for several EEV openings using experimental heat pump system. The sample EEV has over 35 ㎫ burst pressure and the maximum mass flow rate of CO2 through the EEV increased to 100 g/s at full opening condition.