Failure behavior of alumina ceramic plates under multiple high-energy pulsed laser irradiation

This study investigates the failure behavior of alumina ceramic plates under nanosecond high-energy pulsed laser irradiation through combined experiments and numerical modeling. Laser tests were conducted with single-pulse energies from 15 to 60 J and pulse numbers ranging from 1 to 5. Three characteristic damage mechanisms were identified: a heat-affected zone and shock-damaged zone on the front surface, and a spall fracture zone on the rear free surface. Spallation was found to be the dominant failure mode, progressively expanding under repeated pulses and ultimately causing perforation and macroscopic fracture. Microscopic observations reveal that front-surface damage results from coupled thermal ablation and mechanical shock effects, whereas rear-surface spallation is governed by dynamic tensile fracture induced by stress-wave reflection at the free surface. Three-dimensional profilometry shows that spall depth increases with increasing single-pulse energy. Notably, under identical total laser energy, multiple low-energy pulses produce a higher spall growth rate than fewer high-energy pulses. The developed numerical model accurately predicts the macroscopic dimensions of the spall region, demonstrating good agreement with experimental results. (Figure presented.)