T. Butler, Ormond, LLC, Auburn, WA; C. Lei, R. Taylor, M. Yu, NAVAIR-Naval Air Systems Command, Patuxent River, MD
Titanium tubes are widely used for hydraulic lines due to their high strength/density ratio, high toughness and good corrosion resistance. However, the surface flaws induced during manufacturing, installation, or maintenance in the form of scratches, dents, chaffing, etc, lead to shortened fatigue life and potentially catastrophic aircraft damage. Plus, the long lead time to acquire and increasing price of titanium affects readiness and maintainability. An innovative surface treatment is needed to inhibit or block growth of the surface flaws. A newly developed cavitation peening technology, which creates a high compressive residual stress layer on the surface, could be used to enhance the fatigue life of Ti-tubes. The compressive stress stalls/eliminates the flaw growth, in turn improving the fatigue life of hydraulic systems. Preliminary test data show that a cavitation peened tube passed 2.5 times tube design life.
