Simulation of organic coating removal by particle impact

The physical phenomena acting in paint removal by particle impact are not well known. Some simplified models assume that the paint removal is the result of erosion. Our research deals with the comprehension of the physical mechanisms which happen when an abrasive particle impacts a painted substrate. This paper addresses the numerical simulation of the impact of spherical particles on a substrate corresponding to an aluminum alloy sheet (A2024) coated with thermoset polyurethane paint (PAC 33). The behavior of the paint in the real conditions of decoating has been identified by solving an inverse problem using impact tests. Paint removal is the result of three phenomena: first, the initiation of delamination at the beginning of the impact due to major shear stresses at the interface; second, buckling of the paint film due to major radial compressive stresses in the film which come from the particle penetration in the coating; and third, the delamination of coatings by buckling occurs, according to the existing literature, in a combination of both mode I and II (mixed mode). The criterion of delamination is based on the state of stresses at the interface between the substrate and paint. This criterion has been introduced in finite element modeling. The numerical results are compared with experiments.