Composite overwrapped pressure vessel
A composite overwrapped pressure vessel (COPV) is a vessel consisting of a thin, non-structural liner wrapped with a structural fiber composite, designed to hold a fluid under pressure. The liner provides a barrier between the fluid and the composite, preventing leaks (which can occur through matrix microcracks which do not cause structural failure) and chemical degradation of the structure. In general, a protective shell is applied for protective shielding against impact damage. The most commonly used composites are fiber reinforced polymers (FRP), using carbon and kevlar fibers. The primary advantage of a COPV as compared to a similar sized metallic pressure vessel is lower weight, but this may be offset by the increased costs of manufacturing and certification.
A composite overwrapped pressure vessel (COPV) is a pressure-containing vessel, typically composed of a metallic liner, a composite overwrap, and one or more bosses. They are used in spaceflight due to their high-strength and low weight.
During operation, COPVs expand from their unpressurized state.
During manufacturing, COPVs undergo a process called autofrettage. The unit is pressurized and the liner is allowed to plastically (permanently) deform. It comes into contact with the overwrap and results in a permanent volume increase. One reason to autofrettage a vessel is to verify the volume increase across pressure vessels in a product line remain within family. Out-of-family data could indicate possible damage to the vessel.
Three main components affect a COPVs strength due to aging: cycle fatigue, age life of the overwrap, and stress rupture life.
COPVs can be subject to complex mode of failures. In 2016, a SpaceX Falcon 9 rocket exploded on the pad due to a COPV failure : the failure resulted from accumulation of oxygen between the COPV's aluminum liner and composite overwrap in a void or buckle. The entrapped oxygen can either break overwrap fibers or cause friction between fibers as it swells, igniting the oxygen and causing the COPV to fail.
- Gas cylinder – Cylindrical container for storing pressurised gas
- Fuel tank
- Hydrogen tank
- Graphite-Epoxy Motor
- Protective shells for composite overwrapped pressure vessels
- Metal-Lined Composite-Overwrapped Pressure Vessel
- A STRUCTURAL HEALTH MONITORING SYSTEM FOR COMPOSITE PRESSURE VESSELS
- Russel, Rick. "Composite Overwrapped Pressure Vessels (COPV) Stress Rupture Test. Part 2" (PDF). NASA. Retrieved May 25, 2018.
- Kezirian, Michael T. "Composite Overwrapped Pressure Vessels (COPV): Flight Rationale for the Space Shuttle Program" (PDF). AIAA. Retrieved May 24, 2018.
- Tam, Walter H. "DESIGN AND MANUFACTURE OF A COMPOSITE OVERWRAPPED PRESSURANT TANK ASSEMBLY" (PDF). AIAA. Retrieved May 24, 2018 – via Orbital ATK.
- Pat B. McLaughlan; Scott C. Forth; Lorie R. Grimes-Ledesma (March 2011). "Composite Overwrapped Pressure Vessels, A Primer" (PDF). NASA. Archived from the original (PDF) on 2015-04-21.
- Vessel Testing Archived 2008-09-05 at the Wayback Machine
- "Stress-rupture lifetime testing". Archived from the original on 2010-05-27. Retrieved 2008-10-20.
- "SpaceX announces COPV's role in September rocket explosion". 01/02/2017.