Pressure Vessels
Composite Overwrapped Pressure Vessels
A Composite Overwrapped Pressure Vessel (COPV) is an alternative to all-metal pressure vessels. The metal variants were used in space vehicles of the 60s and 70s to store propellants and other fluids. A COPV comprises a metallic liner and an overwrap (that wraps around the liner)—together they contain gases or propellants. Today, fiber reinforced polymers (FRP) are more commonly used over glass for the overwrap, particularly Kevlar® but fibers of carbon are more common now.
A bit of history is that a technology transfer task—involving cooperation between NASA and multiple fire service organizationss in NYC, LA, and Boston—focused on improving respiratory protection for municipal firefighters led to the commercialization of COPVs. Hundreds of thousands of COPVs are now produced per year for commercial applications.
Risks of COPVs
For example for a pressure vessel that is 1,300 cubic inches with storing for example helium or a gas at 9700 psi that is equivalent to 3.6 pounds of TNT.
Their primary advantage over similar-sized metallic pressure vessel is from mass savings—they can be lighter by upto 50%. COPVs, however, carry an increased cost of manufacturing and certification.
The three most important failures modes for COPVs that need to be understood for long-term deep space missions:
- Fatigue crack growth in Liner and crack growth in Boss (?)
- Impact damage
- Stress-Rupture mechanisms
References
The below are resources that may prove useful for [[ Delivering air at this scale in a compressed form sounds logical but would likely require novel solutions. ]]