Numerical simulation and experimental study of cleaning mechanisms in multipulse laser paint removal of acrylic polyurethane composite paint layers on aluminum alloy

To further elucidate the influence of cleaning mechanisms on the effectiveness of laser paint removal, this study presents a comparative analysis between numerical simulations and experimental results for multipulse laser cleaning at three longitudinal overlap rates. The results indicate that under the shielding effect of the laser plasma, the experimental removal depth is consistently lower than the numerical simulation results for the same laser parameters, and intermittent ablation craters are formed in certain regions of the cleaned surface. As the longitudinal overlap rate increases, the residual primer thickness gradually decreases, the deposition amount of topcoating colourant and functional oxides gradually increases, and the ablation behaviour progressively strengthens. The thermal stress has little effect on the removal depth but can induce cracking in the residual primer and the exposed oxide film. The superposition of the remaining plasma enhances the plasma impact and shielding effects. In the laser irradiation zone, the three cleaning mechanisms of ablation, thermal stress, and plasma impact are coupled and interact. In the nonirradiated zone, the plasma impact and its induced secondary ablation and thermal stress mechanisms are coupled and interact.