An enhanced meshless numerical methodology for modelling pulsed laser ablation of aluminium

Laser machining has become increasingly popular given the ability of this manufacturing technique to process a wide range of materials over multiple length scales, i.e., from the micro to the macroscale. In this work, a meshless numerical model based on Smooth Particle Hydrodynamics (SPH) was developed and tested to simulate pulsed laser ablation of aluminium in the nanosecond regime. In this model, the material removal mechanism was based on phase explosion and evaporation in contrast to existing, although still scarce, SPH-based models of laser ablation. In particular, the distinguishing characteristic of the proposed model is that it not only predicts the surface recession due to phase explosion, but also captures the ablation depth due to evaporation at low laser intensity regime. In addition, compared to previous research reports where SPH was employed to simulate laser ablation, the model developed here also comprehensively considered the temperature dependence of the material thermophysical properties as well as the temperature and wavelength dependence of its optical properties. The predicted ablation depths of aluminium following single pulse irradiation were in good agreement with four experimental data sets from two independent experimental studies. These experimental data enabled testing the developed model over a wide range of laser parameters, specifically a pulse fluence value between 0.5 J/cm2 and 46.5 J/cm2, a pulse duration spanning from 0.5 ns to 35 ns and a wavelength for the incident laser comprised between 515 nm and 1064 nm.