A study on failure characteristic of spherical pressure vessel

Currently many aerospace vehicle systems require lightweight, high performance pressurized tank for storage of propellant, nitrogen, oxygen, or other medium. Aircrafts have several needs for high-pressure stored gas, like aircraft escape slide inflation systems, emergency oxygen supply, landing gear actuator, engine pressurized air start system and on-board inert gas generating system nitrogen enriched air receivers. For spacecraft application, the high-pressure gas is utilized for attitude control of the vehicle and propulsion purpose. Therefore, the leakage of the pressure vessel results in serious malfunction of the vehicle system causing a mission failure or mishap. It is prudent to recognize the fact that pressure vessels can fail in spite of high standard of qualification program. This paper reports an experimental investigation of the failure behavior of pressure vessels during high pressure of hydraulic loading. The pressure vessels were manufactured by two different procedures. One method is spin forming and tungsten inert gas (TIG) welding process and the other is blow forming and solid-state diffusion bonding process. The failure behavior has been studied and the effect of forming method has been analyzed. The result shows that the pressurization rate and the acoustic emission signal increasing rate provide a similar tendency for a vessel of integrity, while the signal increasing rate is much higher than the pressurization rate for a vessel with defects. It is clear that the acoustic emission response of the vessel to the pressure loading can be successfully applied to predict the structural integrity and failure behavior of the vessels manufactured with both methods.