Scaling law of launch velocity in laser-induced microparticle impact testing

Laser-induced microparticle impact testing (LIPIT) is a useful method for measuring the dynamic mechanical behavior of materials under ultra-high strain rates by accelerating and launching a single microparticle at high velocity. It is important to establish a scaling law for the laser-induced microparticle launching system to optimize its configurations and improve the achievable velocity of the microparticle. In this study, the physical process of laser-induced microparticle launching is analyzed. A scaling law for the launch system is obtained by dimensional analysis. The influence of dominant dimensionless parameters on the dimensionless velocity of the microparticle is then assessed by numerical simulations. The results show that the dimensionless launch velocity of the microparticle increases with increasing dimensionless energy and dimensionless time of the laser pulse and with decreasing dimensionless thickness of metal and elastomer films and the dimensionless mass of the microparticle. Finally, the dimensionless formulas for predicting the velocity of the microparticle of the launch system with thick-metal-film and thin-metal-film configurations are determined, respectively. This study promotes the understanding of the launch mechanisms of LIPIT and provides a guideline for optimizing its configuration to achieve a wide range of impact velocities of the microparticles.