The 3-way valve have been used as a valve for opening and closing the valve by the flow control in the pressure system of the cryogenic and high pressure environment. In this paper, numerical analysis and experimental study on fracture nipple of 3-way ultra high pressure valve applied to space launch vehicle was carried out. We have developed a 3-way valve numerical simulation modeler of cryogenic environment using commercial software ANSYS 18.2. As results of numerical analysis, optimum nipple condition was derived. In addition, a 3-way valve prototype was fabricated and the fracture test was performed and compared with the numerical analysis results.

As CFRP with only a single material shows the various fracture properties, it has been applied to the many areas through the whole industry. The method bonding with adhesive has been recommended to apply the CFRP to structure. But it is inevitable that the mechanical joints with bolt, nut and rivet have been used sometimes. This study investigates the effect that these joints influence the CFRP panel through the analysis result. The analysis models as CFRP panels with the thickness of 5 mm have four kinds of layer angles which are 30°, 45°, 60° and 75°. The fracture property is examined when the pressure by the mechanical joint is applied to the upper panel. As the joint pressure is distributed most effectively in case of the layer angle of 60°, it is shown that this pressure becomes lower and the deformation of panel becomes lowest. On the basis of this study result, it is thought that the foundation data for the design of CFRP structure can be provided and contributed to the safety design of structure.

As CFRP with only a single material shows the various fracture properties, it has been applied to the many areas through the whole industry. The method bonding with adhesive has been recommended to apply the CFRP to structure. But it is inevitable that the mechanical joints with bolt, nut and rivet have been used sometimes. This study investigates the effect that these joints influence the CFRP panel through the analysis result. The analysis models as CFRP panels with the thickness of 5 mm have four kinds of layer angles which are 30°, 45°, 60° and 75°. The fracture property is examined when the pressure by the mechanical joint is applied to the upper panel. As the joint pressure is distributed most effectively in case of the layer angle of 60°, it is shown that this pressure becomes lower and the deformation of panel becomes lowest. On the basis of this study result, it is thought that the foundation data for the design of CFRP structure can be provided and contributed to the safety design of structure.

콘크리트 중력댐 상부면의 균열에 작용하는 수압의 영향을 주로 고려하여 댐의 파괴거동을 조사하였다. 첫째, 표면적분법에 의하여 응력확대계수를 구하는 경우에 작용하는 수압의 형태를 등분포형태 외에, 삼각형 분포 및 포물선분포도 고려하여 보았다. 둘째, FRANC(FRacture Analysis Code)를 이용하여 균열면에 작용하는 수압의 형태에 따른 기존균열의 전파방향을 추적하였다. 셋째, 월류수위 아래에서 균열이 전파되지 않을 수 있는 한계균열길이를 수압의 분포형태에 따라 구분하여 구하여 보았다. 표면적분법으로 수압의 형태에 따라 응력확대계수를 구한 결과는 FRANC를 이용하여 얻어진 결과와 비교 되었으며 비교적 잘 일치함을 알 수 있었다. 균열면에 작용하는 수압의 형태가 삼각형분포의 경우에 균열의 전파방향은 등분포의 경우에 비하여 댐의 기초쪽으로 기우는 것을 알 수 있었으며, 또한 월류수위 아래에서 한계균열길이는 댐높이의 대략 2/5-1/2되는 곳에서 최대가 됨을 알 수 있었다.