Laser Shot Peening of Landing Gear Components

NCMS Project #: 140158

Problem:

Safety of flight issues due to stressed landing gear.
A variety of landing gear components are failing without having reached their desired service lives.
The failures are due primarily to stress corrosion cracking (SCC) and fatigue.

Benefit:

Availability:
- Increased availability of the T-38 trainer as a result of few failures of landing gear trunnions.
- Business development on other platforms will greatly increase weapon system availability.
Cost:
- $3.1M avoidance for the T-38 main landing gear trunnions.
Reliability:
- Trunnions previous life span – 6 years; extended to 9-12 years.
Cycle Time:
- No significant effect on cycle time.
Safety:
- Increased safety of flight due to less fatigue fractures.

Solution/Approach:

Peening is used to improve material resistance to stress-induced damage such as fatigue and SCC.
The peening process compresses the material just below the surface, resulting in a residual compressed load.
A laser pulse creates a shock wave that drives a residual stress up to 2-mm deep into the metal part. (8x conventional peening).
The increased depth of peening helps prevent crack propagation, and imparts superior performance.
Project developed a more economically favorable system, which pulses at a rate 20x faster than other available systems and can peen about one square meter of metal per hour.

DOD Participation:

Industry Participation: