폭굉을 고려한 압력용기 최대허용압력 결정방법의 제안

최진복 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.5

압력용기의 내압은 압력용기 설계의 중요한 인자이며 이를 바탕으로 관련 설계기준 및 구조해석결과에 따라 압력용기의 두께 및 직경과 같은 기하학적 형상이 결정된다. 그러나 압력용기 내부에서 폭굉이 일어날 경우 이 폭굉압력을 적절히 고려 하여 압력용기를 설계할 수 있는 설계기준은 미흡한 실정이다. 일반적으로 폭굉이 발생할 경우, 초기 폭굉압력이 용기 벽면에 도달하여 반사하는 반사압력은 초기압력의 2배 이상이라고 알려진다. 그러나 폭굉압력은 구조물의 고유주기보다도 짧은 시간 안에 최대치에 도달한 후 급격하게 감소하는 경향을 보이며, 이 경우 실제 용기벽면이 받게 되는 압력은 반사압력에 비해 매우 작을 수 있다. 따라서 본 연구에서는 이러한 폭굉의 특성을 고려하여 압력용기가 견뎌야 하는 적절한 등가의 폭굉압 력을 산정하는 방법을 제안함으로써 폭굉을 고려한 효율적인 압력용기 설계기준을 제시하고자 하였다. The internal pressure is a critical parameter for designing a pressure vessel. The static pressure that a pressure vessel must withstand is usually determined according to the various codes and standards with simple formula or numerical simulations considering the geometric parameters such as diameter and thickness of a vessel. However, there is no specific codes or technical standards we can use practically for designing of pressure vessels which have to endure the detonation pressure. Detonation pressure is a kind of dynamic pressure which causes an impulsive pressure on the vessel wall in a extremely short time duration. In addition, it is known that the magnitude of reflected pressure at the vessel wall due to the explosion can be over twice the incident pressure. Therefore, if we only consider the reflected pressure, the design of the pressure vessel can be too conservative from the economical point of view. In this study, we suggest a practical method to evaluate the magnitude of maximum allowable pressure that the pressure vessel can withstand against the detonation inside a vessel. As an example to validate the proposed method, we consider the pressure vessel containing hydrogen gas.

스패어 타이어 웰 부에 설치되는 Type 4 복합재료 압력용기 설계 및 구조해석

임태훈,변종익,조민식,김한상 한국수소및신에너지학회 2018 한국수소 및 신에너지학회논문집 Vol.29 No.6

Composite pressure vessels made through filament winding are widely used in various fields. Numerous studies regarding composite pressure vessels have been conducted in the automotive industry to improve the space efficiency of trunks as well as the fuel efficiency. Compared with steel liquefied petroleum gas (LPG) vessels used in the conventional LPG vehicles, the use of type 4 composite pressure vessels has advantages in terms of reduction of the weight of vehicles. This study focused on development of type 4 composite pressure vessels that can be installed in the spare tire well. Those type 4 composite pressure vessels are designed with torispherical dome shapes instead of geodecis dome shapes because of the space limitation. To reduce deformation due to the stresses in the axial direction of the vessels, thereby securing the safety of the container, the reinforcing bar concept was applied. A structural analysis software, ABAQUS, confirmed the effect of the reinforcing bar on the axial deformation through the type 4 composite pressure vessel. As a result, the final winding angle of the composite layer was analyzed by applying 26°/28°/26°/28°/26°/88° The tensile stress was 939.2 MPa and the compressive stress was 249.3 MPa.

Elastic-Plastic Stress Analysis and Fatigue Lifetime Prediction of Cross-Bores in Autofrettaged Pressure Vessels

Koh, Seung-Kee The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.9

Elastic-plastic stress analysis has been performed to evaluate the fatigue life of an autofrettaged pressure vessel containing cross-bores subjected to pulsating internal pressure of 200 MPa. Finite element analyses were used to calculate the residual and operating stress distributions of the pressure vessel due to the autofrettage process and pulsating internal pressure, respectively. Theoretical stress concentration factors of 3.06, 2.58, and 2.64 were obtained at the cross-bore of the pressure vessel due to internal pressure, 50%, and 100% autofrettage loadings, respectively. Local stresses and local strains determined from the elastic-plastic finite element analysis were employed to calculate the failure location and fatigue life of the pressure vessel with radial cross-bores, incorporating the low-cycle fatigue properties of the pressure vessel steel and fatigue damage parameters. Increase in the amount of overstrain by autofrettage process moved the crack initiation location from the inner radius toward a mid-wall, and extended the crack initiation life. Predicted fatigue life of the fully autofrettaged pressure vessel with cross-bores increased about 50%, compared to the unautofrettaged pressure vessel. At the autofrettage level higher than 50%, the failure location and fatigue life of the pressure vessel were not significantly influenced by the autofrettage level.

유한요소법을 이용한 고압 CNG압력용기 응력분포 해석

최상인,김영철,김명수,백태현 사단법인 인문사회과학기술융합학회 2017 예술인문사회융합멀티미디어논문지 Vol.7 No.2

Most of the domestic city buses are equipped with the pressure vessels subjected to internal pressure applied by compressed natural gas. Pressure vessels subjected to internal pressure are used in various forms and purposes. Fuel is explosive and has flammable high pressure. The damage of the pressure vessel causes many property damage and loss of life. Safe design for pressure vessel is always necessary. Due to these reasons, many studies using finite element analysis have been conducted. In this paper, the stresses of cylindrical vessel and spherical dome were analyzed using ANSYS, a finite element analysis software. In order to verify the validity of the analysis, a model with a perfectly spherical shape of the dome was designed and observed. Based on the ASME standard in used, stress distribution was also analyzed for models designed with compressed natural gas(CNG). The FEM analysis software agreed with the theory when the dome shape was perfectly spherical. The model designed based on the ASME specification theory, stress concentration occurred in the knuckle part. 환경문제로 국내 시내버스의 대부분은 압축천연가스(CNG)를 연료로 사용하며, 연료 저장용기는 내압을 받는 압력용기를 사용하고 있다. 내압을 받는 압력용기는 여러 가지의 형태와 목적을 지니고 있다. 연료가 가연성이고 고압으로 인한 폭발성을 지니고 있으므로 압력용기의 파손사고는 많은 재산피해와 인명피해를 일으킨다. 이에 대한 안전한 설계가 반드시 필요하므로 유한요소해석을 이용하여 많은 연구들이 진행되고 있다. 본 연구에서 유한요소 해석 소프트웨어인 ANSYS를 이용한 응력해석을 탄성이론의 구형 돔 형상 응력이론식과 실린더 형상 응력이론식을 비교하여 해석의 타당성을 입증 하기위해 돔의 형상이 완전 구형인 모델을 설계하여 관찰하였고 실제 사용중인 ASME 규격이론을 바탕으로 압축천연가스(CNG)로 설계된 모델에 대해서도 응력분포를 분석하였다. 유한요소 해석 소프트 웨어를 사용하여 돔 형상이 완전이 구형인 모델을 해석 하였을 때 이론과 잘 일치 하였고 ASME 규격이론을 바탕으로 설계한 모델에서는 너클부분에 응력집중 현상이 발생하였다.

유한요소법을 이용한 수소충전용 압력용기의 균열에 관한 연구

최하영,변성광,조승현 한국가스학회 2023 한국가스학회지 Vol.27 No.3

As the number of hydrogen filling stations for hydrogen supply increases with the progress of low-carbon eco-friendly energy policies, the risk of accidents is also increasing. Actual pressure vessels may have defects such as notches, pores, and inclusions that may occur during the manufacturing process. Therefore, it is necessary to evaluate the integrity of pressure vessels in the case where cracks exist in pressure vessels under internal pressure. In this paper, 3D finite element analysis was used to evaluate the structural safety of hydrogen-filled pressure vessels with surface cracks, and the shape of surface cracks was compared with the commonly used semi-elliptical shape. In the future, these results will be used to predict the remaining life of the pressure vessel in consideration of fracture mechanics.

상사성 원리를 이용한 복식 압력 용기 열 유동 전산해석

이남권(Namkwon Lee),이종효(Jonghyo Lee),엄석기(Sukkee Um) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

In this study, a computational model based on similarity analysis is proposed to simulate the steam generation phenomena and the inflow pattern of Deionized water(DIW) of the multi-vessel steam generator. Similarity analysis is performed to reduce computation time of multi-vessel steam generator model. Multi-vessel with similarity analysis predicts the possible problems that can occur during the heater malfunction of a pressure vessel. Moreover, two different inflow types of DIW pipeline configurations are compared to find out the best uniform distribution of DIW to all pressure vessels. These results show that the heater malfunction causes the steam flows from normal operating pressure vessels to a malfunctioning pressure vessel. In addition, the results show that the cascade inflow type of DIW pipeline can uniformly supply DIW to all pressure vessels better than parallel inflow type of DIW pipeline.

각형 압력탱크 개발 연구

최윤석 ( Younseok Choi ) 공군사관학교 2016 空士論文集 Vol.67 No.1

기존 사용되던 실린더형 압력탱크와 부피효율을 증대시킨 각형 압력탱크와의 비교 분석을 통하여 현재까지의 각형 압력탱크 개발에서의 문제점을 분석하였다. 부피효율, 동일 두께에서의 응력 비교, 제작비용 등의 조건들을 비교하였다. 이를 통하여 각형 압력탱크가 가진 장단점을 분석하였으며, 다수의 압력탱크보다는 단일 압력탱크가 제작비용적인 측면에서 유리한 것을 알 수 있었다. 또한 각형 압력탱크의 응력을 낮추는 방법으로 판의 두께의 변화, 보강재의 설치 등의 방법으로 연구 수행결과 응력을 낮출 수 있음을 알 수 있었다. 앞으로 보강재의 형상, 두께 등에 대한 보강재 효과와 접합부의 형상 변경 및 보강재 효과 등에 대한 연구가 추가적으로 필요함을 알 수 있었다. Through a comparison between the cylinder-shape pressure vessel that was previously being used and the prismatic-shape pressure vessel with increased volume efficiency, it was analyzed and interpreted the problems that had arisen so far during the development of the prismatic-shape pressure vessel. Conditions involving volume efficiency, the comparison of stress level when the thickness of plates were the same, and production costs were taken into consideration. In the process of analyzing strengths and weaknesses the prismatic-shape pressure vessel had, it was discovered that multiple pressure vessels were more advantageous than a single pressure vessel in terms of production costs. In addition, it was found the way to lower the stress level of the prismatic-shape pressure vessel by altering the thickness of its plate or installing a stiffener. It was figured out that additional research about effect of stiffener shape and thickness, shape of plate junction and junction stiffener were needed.

최적화 설계를 통한 혼합가스 성능시험용 고온 고압 용기의 제작

구현곤(Hyoun-Kon Ku),류형민(Hyung-Min Ryu),안재웅(Jae-Woong Ahn),배영관(Young-Gwan Bae),김진희(Jin-Hee Kim) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.11

In this study, the high-temperature high-pressure vessel was successfully manufactured, which can be used to store pressurized air and to increase the temperature for the mix performance test of high-temperature high-pressure air with coolant (e.g., water). In this research, static structure analysis and transient thermal analysis were performed using the commercial software Midas NFX 2015 R1. Based on the results, the optimized pressure vessel design was carried out. As a result of the optimized design, the minimum stress and minimum weight were found at 120 ㎜ of the vessel thickness, and the optimized pressure vessel was verified. Finally, through manufacture and performance test (e.g., the non-destructive inspection and hydraulic pressure test), the reliability and safety were validated for the designed pressure vessel.

Low-velocity impact response analysis of composite pressure vessel considering stiffness change due to cylinder stress

Elsevier 2017 Composite structures Vol.160 No.-

<P><B>Abstract</B></P> <P>To accurately analyse the transient response and damage of pressurized vessels subjected to a drop impact or foreign object impact, we must consider the change in stiffness due to pre-stress. The pre-stress condition induces a phenomenon where thin plates with in-plane pre-stress show different stiffness during out-of-plane deflections compared to the original plate without the in-plane pre-stress. Because the cylindrical wall of a pressurized vessel is under in-plane pre-stress induced by the vessel’s internal pressure, we must consider the ‘change in stiffness’ to accurately analyse the impact response and damage. In this study, we investigated the low-velocity impact response of a composite laminated cylinder wall of a pressure vessel with high internal pressure. The shear deformation theory of a doubly curved shell and von Karman’s large deflection theory, as well as a newly proposed strain–displacement relation including initial strain terms to consider the stiffness change induced by cylinder stress due to internal pressure, were used to develop a geometrically nonlinear finite-element program. Numerical results that were calculated for the cylinder stress showed larger contact force and smaller deflection. By comparing strain values, a simple superposition of strain value calculated without considering cylinder stress and initial cylinder strain value showed 10–20% more strain than that accurately calculated with considering the stiffness change due to cylinder stress.</P>

수소충전소용 초고압용기(Type I)의 구조 설계 및 피로수명 예측

서영빈,박건영,김철 대한기계학회 2023 大韓機械學會論文集A Vol.47 No.3

Ultra-high-pressure vessel (Type I) is mainly used in hydrogen charging stations because it consists of a single high-strength material with less internal defects compared to other types of vessels. Fatigue fractures are caused by cyclic loads during the charging process in gas stations. Therefore, it is necessary to evaluate the structural safety of the high-pressure vessel. In this study, the ultra-high-pressure vessel was designed according to the thickness suggested by ASME, and its structural safety was evaluated by stress linearization of each part of the vessel and finite element analysis. Furthermore, fatigue life due to cyclic loads at the time of hydrogen charging was predicted using the modified goodman diagram and was verified by fatigue simulation. 초고압용기(Type I)는 주로 수소충전소에서 사용되며, 다른 형태의 용기에 비해 내부결함이 적은 고강도의 단일재로 구성된다. 그러나 초고압수소 충전 시 가압과 감압과정을 거치며, 초고압용기 내부에 반복하중에 의한 피로파괴가 발생한다. 따라서 초고압용기 설계 시 구조건전성에 대한 평가가 필요하다. 이에 본 연구에서는 ASME 규격을 통해 용기의 두께를 계산하여 수소충전소용 초고압용기를 설계했고, 용기의 각 부위별 응력선형화를 통해 구조건전성을 평가했다. 또한, 수소충전 시 반복하중에 의한 피로수명을 수정된 굿맨선도를 통해 예측했고, 피로해석을 통해 검증했다.