Numerical Simulation and Surface Morphology of Laser-Cleaned Aluminum Alloy Paint Layer

The finite clement model for an acrylic polyurethane paint layer cleaned by a nanosecond pulsed laser on a 2021 aluminum alloy surface was established using COMSOL, Multiphysics. The effects of different parameters on the laser cleaning temperature field and cleaning depth were analyzed, and the findings were verified by an experimental study. The results show that the scanning speed affects the cleaning efficiency in the form of an overlapping rate, where a low scanning speed corresponds to a reduced cleaning rate. A suitable cleaning efficiency is achieved with an overlapping rate of 50%. As the laser energy density increases, the maximum surface temperatures of the paint layer and the substrate increase linearly. When the laser energy density reaches 25 J/cm(2), the paint material in the laser irradiation region is completely removed and the ablation depth of the aluminum alloy substrate is 50 mu m. For a laser energy density of 25 J/cm(2) and an overlapping ratio of 50%, the peak-to-valley height of the substrate surface groove is 50.234 mu m. Thus, a suitable surface that meets the coating process requirements can be obtained with these parameters. These results provide a reference for studying nanosecond pulse laser cleaning and for selecting appropriate process parameters.