Laser peening systems using a robotically controlled laser beam facilitate uniform peening of large and complex shaped components. Photo courtesy of Metal Improvement Company.
To assess and utilize the benefits of a new technology called laser peening to improve the strength and extend the life of critical aircraft structural, turbine engine and drive train components.
Laser peening replaces the hammer blows and streams of beads of ball peening and shot peening with short blasts of laser light, which creates a piece of metal with significantly improved performance and fatigue failure. With each pulse of the laser, an intense shock wave is created over a roughly 5-millimeter by 5-millimeter area and drives in a residual compressive stress about 1 to 2 millimeters deep into metal. In conventional peening, this compressed layer is approximately 0.25 millimeter deep.
This program will evaluate the residual stress level and compressive layer depth as a function of laser beam intensity, develop a model that predicts residual stress distribution to include location and distribution of positive stress profiles, and conduct metallurgical evaluations of simulated specimens to determine characteristics of any defect after peening and then after surface finishing.
Laser peening has substantial advantages over conventional shot peening relative to fatigue strength improvement, depth of compression layer and process control. The increased compression depth creates a superior ability to keep cracks from propagating and extends the life of parts three to five times over that provided by conventional treatments.
The NMC project is a six-task effort that includes the development and optimization of the laser peening process prior to its application in the material evaluation, demonstration and validation tasks.