A composite overwrapped pressure vessel (COPV) is a vessel consisting of a thin, non-structural liner wrapped with a structural fibercomposite, 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.[1][2] The most commonly used composites are fiber reinforced polymers (FRP),[3] 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.
Casing of the Altair rocket stage, essentially a fiberglass composite overwrapped pressure vessel
Overview[edit]
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.[4] They are used in spaceflight due to their high-strength and low weight.[5]
During operation, COPVs expand from their unpressurized state.[6]
Manufacturing[edit]
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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.[5][7]
Testing[edit]
Various tests and inspections are performed on COPVs, including burst test, stress-rupture lifetime, and nondestructive evaluation.[8][9]
Aging[edit]
Three main components affect a COPVs strength due to aging: cycle fatigue, age life of the overwrap, and stress rupture life.[4]
Failures[edit]
COPVs can be subject to complex mode of failures. In 2016, a SpaceXFalcon 9 rocket exploded on the pad due to a COPV failure[10] : 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.
See also[edit]
Water Pressure Vessels
Gas cylinder – Cylindrical container for storing pressurised gas
Pressure Vessel Design Project Pdf
References[edit]
Composite Pressure Vessels Pdf Writer
^Protective shells for composite overwrapped pressure vessels
^A STRUCTURAL HEALTH MONITORING SYSTEM FOR COMPOSITE PRESSURE VESSELS
^ abRussel, Rick. 'Composite Overwrapped Pressure Vessels (COPV) Stress Rupture Test. Part 2'(PDF). NASA. Retrieved May 25, 2018.
^ abKezirian, 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 TestingArchived 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.
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