ON LASER-INDUCED SINGLE BUBBLE NEAR A SOLID BOUNDARY - CONTRIBUTION TO THE UNDERSTANDING OF EROSION PHENOMENA

Cavitation erosion is an especially destructive and complex phenomenon . In order to understand its basic mechanism, the dynamics of laser-in duced vapor bubbles have been investigated. Special experimental devic es have been used to record ultrafast visualizations and pressure meas urements. From these measurements, the different sources of stresses, induced on the solid wall by the presence of the bubble (shock wave, m icrojet), have been characterized. The ''water hammer'' pressure assoc iated with the microjet velocity varies up to 210 MPa. When the bubble collapses near a solid wall, the pressure emitted is less than in an infinite medium. Pressure values up to 2.5 MPa have been found. These values have been associated with the duration of the pressure applied to the solid wall, which is about 30 ns for the microjet and more than 300 ns for the shock wave. These results have been correlated with th e analysis of damage created on the surface sample. (C) 1998 American Institute of Physics. [S0021-8979(98)02422-0]