2.9 Document the process, findings, and explore follow-on applications

In review, HEI feels that the stated goal of this Phase I SBIR, which was to evaluate a number of typical filament wound fibers in a number of typical as well as experimental resin matrix systems in order to evaluate their capabilities with respect to filament wound pressure vessels used at cryogenic temperatures, has been achieved in its entirety.

HEI considers the data gathered from this SBIR to be extremely useful. By comparing burst results of both cryogenically "treated" and non-cryogenically "treated" cylinders, significant accomplishments have been made:

• The results of the testing expanded the overall database of cryogenic pressure vessels and demonstrated that all of the material systems performed differently at ambient temperature after being cryogenically tested.
• Most of the typical filament winding material systems tested degraded in performance at ambient temperatures after having been cryogenically tested.
• Knowing what material systems degraded in performance and by how much, is valuable information, but something HEI believes to be even more valuable information is the fact that one material system showed essentially no degradation (T-1000 with the cryogenic experimental resin) and another system (T-1000 prepregged with UF3325-95) demonstrated a significant increase in performance. HEI is in the process of filling out a Disclosure of Invention and New Technology for this new technology and intends to explore this further.
• Also, several of the material systems tested showed improvements in consistency (smaller coefficients of variation), even though their overall performance degraded. This was somewhat of an unexpected result, but something that offers huge potential.
• Data has been gathered on the microscopic effects on composite materials when exposed to cryogenic temperatures. This information helps in understanding why composites behave the way they do when exposed to cryogenic temperatures.
• Data has been collected on the effects of a crack resisting barrier. HEI believes that this new technology has significant potential for increasing cryogenic vessel performance and is completing a Disclosure of Invention and New Technology form with the assistance of Dr. DeLay of NASA for this technology. Again HEI intends to explore this technology further.

Arguably the most innovative part of the effort performed to date was the discovery of at least one fiber/resin system that data showed to actually improve in performance following the cryogenic "treatment" it was subjected to. The Toray T-1000 UF-3325 material system showed a slight improvement in median burst and what HEI considers to be a significant decrease in the variability of burst (as measured by coefficient of variation) following the cryogenic treatment. The end result was a pressure vessel population with a usable performance increase in excess of 10%. To be able to achieve 10% more performance out of arguably the highest performing material available, is without question innovative and significant. HyPerComp Engineering intends to pursue the previously mentioned developments and is submitting a proposal for Phase II funding to do that. Should HEI be granted an SBIR Phase II follow-on, it is intended to take that test data, expand upon it, and develop an "off the shelf" technology for the design and analysis of filament wound composite pressure vessels for all types of cryogenic and very cold applications. HEI believes this to be innovative because research has shown that these types of vessels, for these types of applications, with proven and reliable capabilities do not currently exist.

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