Effect of Laser Shock Peening (LSP) on the Fatigue Life of Complex Panel Structures in a Butt Joint Configuration
S-X. Mao, J. Du, Z-P. Yin, Y. Chen and J-W. Tian
Laser shock peening (LSP) is mainly used for machining complex structural parts in aviation and so it is of significance to investigate how the machining parameters influence the fatigue life of the complex aerostructure. Herein we describe how we carried out fatigue tests on 2024-T351 alloy aircraft wing panel structures, which adopted different laser power density peening strategies. Simulation of the stress at the edge of the hole is also carried out. It is found that in Strategy A there are cracks on the inner wall of the hole and the fatigue life decreases, while in Strategy B there are corner cracks and the fatigue life increases. The main reason is that the pressure wave peak has a large effect on the residual stress distribution in the structure. In Strategy A the laser power density is too large, the structure appears to demonstrate that residual tensile stresses lead to structural life reduction.
Keywords: Nd:YAG laser, 2024-T351 alloy, laser shock peening (LSP), butt panel, fatigue life, peak pressure, finite element method (FEM)