Simulation on mass removal by recoil pressure, thermal stress, and bubble growth of concrete irradiated by a millisecond Nd: YAG pulsed laser

Abstract

The present paper reports on the study of millisecond pulsed Nd: YAG laser ablation of concrete material using the finite element method simulation to elucidate the complex mass removal processes such as melt ejection by recoil pressure, spallation as a result of thermal stress and gas bubble growth which are not well documented. The simulated results showed that the mass removal of concrete by melt ejection dominates over evaporation. Effects of laser intensity and linear laser pulse overlap on mass removal of concrete were also discussed. When the laser intensity was varied over a range from 2.4×1010 W/m2 to 4.4×1010 W/m2, both the temperature and mass ablation increased, however, the ablation efficiency remained constant i.e. 0.18 mg/J indicating the mass removal process remained unchanged. The simulated results are validated with both the experimental data and analytical results.