TITLE:

NASA Modeling and Testing for Determination of Stress Rupture Reliability of Composite Overwrapped Pressure Vessels

DATE:

Friday, March 20th, 2015

TIME:

3:30 PM

LOCATION:

GMCS 214

SPEAKER:

Dr. Lorie Grimes-Ledesma. NASA

ABSTRACT:

Composite Overwrapped Pressure Vessels (COPVs) are used to store high-pressure gas in nearly every NASA spacecraft. Long-term reliability of these pressure vessels is dependent on understanding and mitigating failure modes. Stress rupture is a composite failure mode that affects COPVs. Tests demonstrate that it is a function of time and tensile stress and results in failure of the composite below ultimate load. Because the underlying failure mechanism is not understood, reliability of a COPV failing in stress rupture has been determined in the past based on empirical models using established statistical techniques. Studies by NASA found that the models typically used by industry for estimating the threat of stress rupture were not supported by an adequate set of experimental data. To address this data shortfall, NASA is currently performing a very large test program of strands and vessels under various tensile loads and pressures. This discussion will describe the models used and the testing underway to support understanding of the long-term reliability of COPVs.

HOST:

Dr. Satchi Venkataraman

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