Laser Peening for Improved Fatigue Strength and Lifetimeof a Wing Attachment Shear-Tie

Author:  L. Hackel, T. Heidenberger, J. Rankin, Jack Campbell, and Tom Mills
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.220-225)
Doc ID:  2014079
Year of Publication:  2014
Abstract:  
Laser peening is shown to improve fatigue strength and life in test parts simulating the Al-7050-T7451 wing attachment shear tie for an operational Navy aircraft. Fatigue tests were conducted on parts fabricated and treated in accordance with the processes in current use (ion vapor deposition (IVD) coated and shot peened) and others with laser peening added. Additional parts were prepared with a 0.25 mm deep EDM notch to simulate damage or crack initiation. Without exception, laser peening outperformed all otherwise prepared specimens by as much as 10 times for the case of the notched ( simulated damage) specimens. Laser peening is a deterministic, robotically applied process for which the Navy allows taking fatigue life credit.