Finite Element Simulation of Waterjet-Peened Al 7075-T6 Aluminum Alloy Surface by Using Multiple Droplet Impacts

This paper presents simulation of waterjet peening process based on finite element (FE) modeling with adjacent water droplet sets, which impact the material at high velocities. This simulation allows predicting the peened surface integrity including residual stresses, plastic strains, surface roughness and superficial damage. The proposed modeling considers both a mono-set and multi-sets of water droplets presenting an exponential distribution of an impact velocity, which depends on the principal parameters of the waterjet peening process. The Johnson–Cook material behavior law is adapted in this modeling. The validity of this simulation is studied for a waterjet-peened Al 7075-T6 aluminum alloy. The FE modeling is discussed with the effects of several factors and configurations (droplet diameter, repeated impacts, additional covering and multi-sets impact), and the numerical results are compared to the experimental ones. It is found that the low droplet diameter dw = 0.3 mm permits to have a lower surface integrity than that with diameter dw = 0.5 mm, which is clearly better. The effects of repeated impacts and additional covering induce an increase in the surface integrity. The FE modeling, using the impacts of multi-sets, allows having a good agreement with the experimental results.