Stripping process modelling: interaction between a moving waterjet and coated target

This paper deals with the numerical modelling of stripping process by a mono-jet moving tool. The example of aeronautic coating (polyurethane) deposit on an infinite homogenous metal (A2024) was treated. The numerical computation was carried out using Dyna3D code. In order to study the jet-target interaction, we have used an eulerian description for the fluid (waterjet+air) and a lagrangian formulation for the target. The interaction between the two meshes is based on euler-lagrange coupling. The Hydrodynamic results show the importance of the jet flattening on the treated-coated 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. Our results were demonstrated by experimental tests. (C) 2002 Elsevier Science Ltd. All rights reserved.