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부하-강도 분석을 이용한 격막형 펄스분리장치의 내열강도에 대한 신뢰성 예측 사례연구
이동원(Dong-Won Lee),정세용(Se-Yong Jeong),이방업(Bang-Eop Lee),정규동(Gyoo-Dong Jung),박부희(Boo-Hee Park),안동근(Dong-Geun An),장중순(Joong-Soon Jang) 한국신뢰성학회 2015 신뢰성응용연구 Vol.15 No.2
A stress-strength analysis is used to assess the reliability of a multi-pulse rocket motor system. Main stress is found to be thermal during explosion and the distribution is obtained by simulation. The strength distribution is derived from the results of actual specimen tests. The failure rate of barrier type pulse separation device is estimated.
추진제 그레인 래디얼 슬롯내의 폼 코어에 의한 압력증가 해석
김종율,정규동,양준서,Kim Jong-Yul,Jung Gyoo-Dong,Yang Jun-Seo 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.4
The radial slot configuration in the solid propellant grain is usually fabricated by the polyurethane foam slot former The foam cannot be easily removed from the solid propellant, some can remain in the slot. Analogue solid propellant rocket motors using polyurethane foam to shape the slot are static fired with the foam former still in place in the slot. The pressure increases at the slot part are measured and there are indications of the propellant cracks at the insulations above the slot. The pressure increase is produced at the beginning of the burning sequence as the foam will hinder the combustion gas of the burning propellant from flowing into the central bore. The pressure increase up to about 300psi is predicted for the motor tested and this pressure increase depends on the gap between the propellant and foam surfaces and remaining foam volume. This amount of pressure increase inside of the slot is estimated to cause the propellant crack. To prevent this pressure increase, minimizing the foam remainder in the slot and making sufficient chamfering at the comer of the slot entrance are suggested.
박정호(Jung-Ho Park),유남선(Nam-Sun Ryu),박재범(Jae-Beom Park),정규동(Gyoo-Dong Jung) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5
고체 추진기관의 HTPB 추진제는 저장소에서 저장소 온도에 따라 물리적, 화학적 노화가 진행된다. 추진기관 수명은 HTPB 추진제의 노화도에 의해 결정되며, 추진기관 수명은 생산 초기에 점탄성 특성 및 노화 시험을 통해 예측된다. 본 논문에서는 생산 초기 물성 및 가속노화 시험을 통해 획득한 노화물성과 장기 저장된 자연 노화된 물성을 비교 분석 하였다. 획득된 초기 및 노화물성 결과를 적용하여 중공형 그레인의 온도 하중에 의한 변형율을 분석 하였다. HTPB propellant of Solid Rocket Motors ages by variable temperature at a storage place. Solid Rocket Motor Shelf-life depended on an aging ratio of HTPB propellant and estimated a shelf-life time through the viscoelastic property and aging test. This paper was analyzed an initial and natural aging properties during long term storaged, initial properties was obtained from characterization and accelerated test results. Cylindrical grains analyzed a strain by thermal load applying acquired test result.
불균질 취성재료 파괴인성에 미치는 두께효과의 확률적 연구
김엄기,고성위,정규동,Kim, Am-Kee,Koh, Sung-Wi,Jung, Gyoo-Dong 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.4
Fracture toughness of heterogeneous brittle materials such as poly crystalline ceramics used to present the size (thickness) effect as well as statistically distributed results. There is belief that both(size effect and scatter) must be associated with each other. However, no generally accepted theory has been established so far. Using statistical approach, a probabilistic modeling for the fracture toughness which describes the thickness effect was attempted in this paper, Weibull distribution of specific fracture energy(SFE)at local areas and Griffith criterion are applied to the model. In addition, the newly developed model was verified with experimental results of alumina.
변형률 모사 실린더를 이용한 추진기관 건전성 평가 기법 개발
박재범(Jae Beom Park),박정호(Jung-Ho Park),김신회(Shinhoe Kim),정규동(Gyoo Dong Jung) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
온도하중하에서 고체추진제의 역학적거동을 확인하기 위한 변형률 모사 추진제 충전체(SEC)가 설계되고 제작되었다. 제작된 충전체에 DBST 센서를 부착하였으며, 이를 통해 온도하중하에서의 추진제/라이너계면의 수직응력을 측정하였다. 수행된 연구결과를 토대로 DBST 센서가 부착된 SEC의 유용성을 확인하였으며, 이를 활용한 고체로켓추진기관의 노화진행을 정량적으로 확인하고 신뢰도를 추정할 수 있는 기법을 제안하였다. A strain evaluation cylider (SEC) is designed and fabricated to check the mechanical behavior of solid propellant subjected only to thermal loading. Dual Bond Stress and Temperature (DBST) sensors were adopted to SEC and the interface normal stress between propellant and liner was checked with the temperature at the same time and position. The obtained results showed the usefulness of the SEC with DBSTs for the quantitative evaluation of the aged state of solid rocket motor (SRM) and a methodology for the reliability estimation of solid rocket motor was proposed.
Cohesive Element 기법을 적용한 고체추진제의 균열진전해석
박재범(Jae Beom Park),박재균(Jae Gyun Park),김재훈(Jae Hoon Kim),정규동(Gyoo Dong Jung) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.5
고체추진제의 대표적인 파괴현상은 응력집중부위에 형성되는 파손진전영역에서의 균열 발생 및 진전이며, 이는 비선형 파괴역학개념인 파괴에너지 기법을 적용하여 효과적으로 평가할 수 있다. 본 연구에서는 실험결과을 기반으로 한 접착요소모델을 구성하여 균열진전을 모사하였으며, 쐐기분리시험을 실시하여, 파괴에너지를 평가하였고 안정적인 균열진전이 관찰되었다. The typical fracture process of solid propellant is crack initiation and propagation in the failure process zone(FPZ), which is formed at the stress concentration region. In this study, a nonlinear fracture mechanics approach, such as fracture energy, was applied to evaluate the fracture toughness of solid propellant and a cohesive model was constructed for the crack propagation analysis based on the experimental results and finite element method. The fracture energy GF measurement was conducted by the Wedge Splitting Test(WST) and very stable crack propagation was observed.
HTPB 추진제 노화 특성 및 HFC 기반 수명 평가 기법
조원호(Wonho Cho),웨스트룬드(M. Westerlund),류백능(Baek-Neung Ryoo),정규동(Gyoo-Dong Jung),유지창(Ji-Chang Yoo) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.5
HTPB 추진제는 자연 저장 기간 동안 내부 시효성 물질들에 의한 물리․화학적 반응으로 인해 서서히 노화가 진행된다. 각기 다른 시간-온도 조건에서 이들 시효성 물질의 가속 노화 시험을 통해 자연상태에서의 노화 특성을 모사할 수 있다. 본 논문에서는 장기 저장 기간 동안 느리게 진행되는 HTPB 추진제의 물리 화학적 반응에 의한 노화 특성을 HFC(Micro-Heat Flow Calorimeter)로 분석 평가하여 수행한 HTPB 추진제의 신개념 수명 예측 기술에 대하여 고찰하였다. During natural ageing of HTPB propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behaviour at different time-temperature conditions especially focused on the in-service conditions. Ageing behaviour of HTPB propellant were investigated using HFC(Micro-Heat Flow Calorimeter) is universal technique for measuring the rate of slow chemical and physical processes in long-term storage.