4. Conclusion

4.1 Summary

From the tests conducted and discussed in this paper, it is apparent that the HEI/NASA new technology does increase robustness of the cylinders where the technology is applied. Increased robustness was demonstrated in the increased performance of the cylinders in both low and high velocity impact scenarios. It is also apparent that the technology must be applied in the correct way to create optimized robustness. Besides process and hybridization techniques, which carbon fiber is chosen to hybridize with Zylon does make a difference.

4.2 Caveats

Although Zylon does have excellent properties that can make it work well, it must be used with some caution because of its tendency to creep over time. Zylon can also be difficult to make aesthetically pleasing. Because of Zylon's toughness, it will neither machine nor sand well. Zylon fiber is also extremely sensitive to ultra-violet rays and will degrade rapidly if not properly protected.

4.3 Applications

The thin walled nature of aerospace and defense pressure vessels makes them susceptible to damage. As such a more robust cylinder should be appealing to aerospace and defense applications. The composite pressure vessel industry is constantly on the lookout for improvements in composite pressure vessels.

5. References

1. THE CRYOGENIC EVALUATION OF TYPICAL AND EXPERIMENTAL FILAMENT WINDING MATERIALS IN COMPOSITE PRESSURE VESSELS NASA CONTRACT NUMBER NAS8-03027; FINAL REPORT
2. Transportable gas cylinders--Fully wrapped composite cylinders. European Standard EN 12245:2002
3. PEARCE, G., 1993 Taguchi Methods, A Hands on Approach. Massachusetts: Addison Wesley Publishing Company.

Copyright 2004 by HyPerComp Engineering, Inc. Published by Society for the Advancement of Material and Process Engineering with permission.

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