Fatigue Life Extension of AA2024 Specimens and Integral Structures by Laser Shock Peening

Abstract

Abstract. The goal of the present study is to understand the effects of laser shock peening (LSP)-induced residual stresses on the fatigue crack propagation (FCP) behaviour of the commonly used aircraft aluminium alloy AA2024 in T3 heat treatment condition. LSP treatment was performed using a pulsed Nd:YAG laser on compact tensile C(T)50-specimens with a thickness of 2.0 mm. LSP-treated specimens reveal a significant retardation of the fatigue crack propagation. The fatigue crack retardation effect can be correlated with the compressive residual stresses introduced by LSP throughout the entire specimen thickness. A possible application of the LSP process on a component like panel with three welded stringers representing a part of a fuselage structure was performed as well. The skin-stringer AA2024-AA7050 Tjoints were realised through stationary shoulder friction stir welding (SSFSW), a variant of the conventional friction stir welding process. In this relatively new process, the shoulder does not rotate and therefore does not contribute to the heat generation. Consequently, a reduced and more homogeneous heat input leads to a less affected microstructure and better mechanical properties. The efficiency of the LSP process has been demonstrated resulting in an increase of 200 -400% in fatigue lifetime.

Advanced Materials for Mechanical Engineering: Ultrafine‐Grained Alloys with Multilayer Coatings

“…One procedure for increasing the fatigue resistance, corrosion resistance, and wear resistance in materials used in heavily loaded products is by laser‐shock peening (LSP). [ 96–100 ] The LSP process has been investigated by several research groups from Russia, Germany, the United States, and China. This technology has prospects as a finishing operation in the manufacture of heavily loaded parts.…”