2.4Fabricate the test population of pressure vessels

A total of 49 pressure vessels were fabricated at HEI with the purpose of being cryogenically tested; 7 vessels for each of 7 different configurations. It was also necessary to design and fabricate a cascade cylinder for the cryogenic test setup. Toray T700 12K fiber impregnated with UF3369-100 was used. Two cylinders were fabricated and one was hydrostatically burst tested at ambient conditions to establish baseline performance. The configurations were:

All of the pre-preg winding was performed on an Entec model PW12 laboratory-winding machine. This machine and the associated delivery system have been specifically configured to wind with prepreg fiber. Tension was set and monitored at a constant 10 lbs per tow/strand. A photo of a cylinder being wound on the PW12 follows.

All wet resin winding was performed on an Entec model PW65H-120-4-25 winding machine specifically set for wet winding.

The cure cycle for the TCR prepreg materials consisted of ramping the temperature up to 160ÅF, holding for 20 minutes, ramping to 300ÅF and holding for one hour. A slow cool down was then implemented with oven doors closed. The Epon 828 cylinders saw the same cure cycle. The NASA experimental resin was ramped to 165ÅF and held for two hours. It was then ramped to 185ÅF and held for two hours. Again, a slow cool down was implemented. All cylinders were cured hanging vertical in the oven with no attempt to rotate during the cure cycle.

Dr. Thomas K. DeLay of NASA made four more configurations of cylinders that HEI tested for "fire for effect". Each configuration consisted of two cylinders, one of which was burst to establish a baseline performance for the cylinders. The second cylinder of each configuration was cryogenically cycle tested and subsequently hydroburst at ambient conditions.

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HyPerComp Engineering, Inc.; SBIR NAS8-03027 Final Report