Prediction of Water Jet Peening Effects on Surface Integrity and High Cycle Fatigue Behavior of Al 7075-T6 Aeronautic Aluminum Alloy

High-pressure waterjet peening consists in striking the material surface with water droplets to introduce beneficial compressive stresses. This beneficial effect permits to enhance the fatigue resistance of many materials and in particular the aluminum alloys commonly used in the aeronautical field. This paper is about a numerical simulation allowing controlling the impact of the process factors on the induced properties and the high cycle fatigue (HCF) life of the treated material. The proposed methodology is composed of three steps: (i) Development of a FE simulation of the waterjet peening process, based on uniformly distributed droplet impacts and taking into account the main parameters of the waterjet. (ii) Numerical simulation of surface characteristics variation during fatigue test and estimation of their stabilization, and (iii) estimation of the waterjet-peened material’s Wöhler curve by using Dang Van’s criterion. This predictive procedure has been studied and verified for a waterjet-treated Al 7075-T6, subjected to rotative bending fatigue test.