Modeling and experimentation of scouring by water jet high pressure

This paper deals with the 3D-numerical modelling of decoating process by a moving waterjet tool. The example of aeronautic coating (polyurethane) deposit on an infinite homogenous metal (A2024) was treated (case of plane keelson). The numerical computation was carried out using DYNA3D code. Hydrodynamic results show the importance of the jet flattening on the treated target. It appears clearly that moving watertjet introduces during decoating process shear stresses causing coating removal by erosion mode. The latter has been simulated thanks to a failure criterion of Lagrangian elements illustrating the coating removal under high velocity moving waterjet. This erosion is accentuated by waterjet stretching effects, which cause tearing of the coating. Consequently, discontinuous cracks at the median line of the coating imprint can be observed. These cracks can be privileged sites, which are traversed by speedy micro-jets accelerating the coating removal. The results were demonstrated by experimental tests.