No abstract

Launch and space vehicle structures are required to be extremely weight efficient. The need to achieve the performance required for the engine in the upper stage of a launch vehicle, increase the payload capacity drives rocket engine manufacturers to seek higher thrust level, specific impulse and thrust to weight ratio. The use of high temperature C-C composite materials is an efficient way to reach these objectives by allowing use of high expansion ratio. Nozzle extensions benefiting of the outstanding thermal, mechanical and fatigue resistance of these materials to decrease mass and featuring high temperature margins. A three-directionally reinforced (3D) carbon-carbon (c-c) material nozzle exit cone is selected for the current study. C-C composite exit nozzle must possess excellent stability and strength under extreme conditions for a specified amount of time. Carbon-carbon composites are appropriate materials for applications that require high specific strength at elevated temperatures. The paper describes the thermo structural analysis of a typical c/c nozzle exit cone.

Rocket motors are used worldwide in both upper and booster stages.Solid rockets can provide high thrust for relatively low cost. Considering the large size of solid motors, these motors are to be designed as segmented motor cases. Segmented motor cases have to be joined by segment joint. Segment joint with tongue and groove configuration provides performance reliability in effective sealing of joints. A tongue-and-groove arrangement employs a pressure-energized metal seal which expands radially when the cylinders are internally pressurized. The radial expansion enhances the sealing effect of the metal seal between the tongue and the groove. Metal end rings welded to the shell motor cases and shear pins for the final assembly provides the sealing. The load sharing among the pins depends on the presence of the slit in a ring, whole & pin dimensional clearances, internal pressure and friction between the metal end rings. Structural analysis of a discontinuous metallic segment ring and shear pins iscarried out in this study. Structural analysis is based on detailed solid model for the segment joint. The load augmentation in the shear pin near the discontinuity is worked out based on a load augmentation factor derived out of FE analysis. The study further extended to a deviation in a nearby hole / pin combination at the vicinity of the discontinuity and is presented in this paper.