Time-resolved dynamic tensile spall of pure aluminum under laser irradiation

A diagnostic technique with high time resolution in the velocity-history measurement is presented by coupling an electronic streak camera with a push-pull type velocity interferometer system for any reflector. This technique has been applied to investigate the dynamic tensile spall induced by laser irradiation in pure aluminum by measuring the free surface velocity profiles of samples. Laser irradiation intensities are in the range of 1010-1012 W/cm2. Spall strength in pure aluminum is calculated from the measured free surface velocity profile as a function of the tensile strain rate. The results show a rapid increase with the tensile strain rate more than 106 s-1. The damage influence on the tensile spall of laser-irradiated pure aluminum is analyzed by experimental and numerical studies. In the frame of percolation theory, a physical model is proposed to describe the rapid stress release due to void coalescence. A good agreement between the calculation and the experiment is obtained