In-service Repair of Fatigue and Stress Corrosion Cracks on US Navy Aluminum Structured Watercraft using Laser Peening

Existing repair methodologies for cracked structures aboard US Navy ships are currently limited in efficiency and effectiveness. New repair methodologies that directly address the local stress states leading to fatigue cracking and stress corrosion cracking are possible with laser peening technology. The proposed laser peening solution allows repairs independent of the cracked structure geometry, requires no hazardous chemicals, requires no additional NDI, and does not jeopardize the existing structure or corrosion resistance of the material. To demonstrate this materiel solution, proof of concept is demonstrated through a rigorous coupon testing program that replicates in-service cracking conditions and the treatment of these crack conditions via laser peening. Further technology developmental efforts are focused on identifying requirements, options, and an optimal solution for a portable laser peening system design. The laser peening system concept will be designed to meet the key performance metrics for the laser peening process, the size and mobility requirements for shipboard usage, and the hazard mitigation requirements for laser peening in an open environment. The portable laser peening system is anticipated to achieve significant cost savings in comparison to conventional laser peening systems through the use of commercial off-the-shelf (COTS) components.