Effect of Beam Incident Angle on the Energy Distribution and Damage Characteristics of Laser Paint Removal Spots on an Al Alloy Surface
W-F. Yang, C-Y. Fu, Z-R. Qian, Y. Cao, T-Q. LI, H-Z. Zhang and S-L. Li
The protection and removal efficiency of laser paint removal from an Al alloy substrate on aircraft is closely related to the energy distribution of the laser spot and material damage threshold. The change of laser incident angle will directly change the energy distribution form, material damage threshold and paint removal efficiency of the material surface. MATLAB was used to simulate the spot morphology and energy centres distribution of different angles, to study the damage threshold of a 2024-T3 Al alloy and paint at different incidence angles by reference to the ISO 11254 1-on-1 laser damage threshold fluence test method, and to analyse the two-dimensional (2-D) and three-dimensional (3-D) morphology of the single-pulse laser spot and verify the results with the simulation. The results have shown that as the laser incidence angle decreases, the spot area increases and the threshold decreases, which effectively improves the energy availability rate and paint removal efficiency. The depth of the actual single-pulse action crater in the material was not affected by the angle of incidence, but the area increases and the offset of the energy centre on the geometric centre of the spot increases. The experimental and simulated values of energy density distribution, offset and craters diameter were well correlated and the errors were explained in terms of the mechanism of laser-material action.
Keywords: Fibre laser, 2024-T3 Al alloy, laser paint removal, incidence angle, damage threshold fluence, light spot energy distribution, damage characteristics