J. Phys. IV France
Volume 110, September 2003
Page(s) 887 - 892

J. Phys. IV France
110 (2003) 887
DOI: 10.1051/jp4:20020806

Asymmetric collapse and micro-jetting in shock wave propagation in porous materials

J. Ribeiro, J. Campos, I. Plaksin, R. Mendes and J. Góis

Laboratory of Energetic and Detonic, Mechanical Engineering Department, Pinhal de Marrocos, Polo II, 3030 Coimbra, Portugal

Streak records of the observation, with a nanosecond and micrometer scale resolution, of the light emitted during the Shock Wave [SW] propagation in epoxy Syntactic Foams [SF], are presented as a function of the HGMS sizes (d 50 = 42, 92 and 135  $\mu$m), the initial density (0.64, 0.81 and 0.92 g/cm 3) and the loading intensity (20.0 and 9.6 GPa). The obtained streak records allowed the determination of the SW velocity, the spatial profile of the intensity of the transmitted SW and the period of light oscillations. The SW velocity was found to change with the density and with the size of the HGMS. The intensity of the transmitted wave, for the samples prepared with medium and large HGMS sizes, shows to be above the values for the samples prepared with small size HGMS. For the samples with the smallest density the values of the period of light oscillation are very close to the time for the propagation between two consecutive layers of HGMS. The experimental facts point to a pulsed propagation process where the mechanism of asymmetric collapse and jet formation is dominant.

© EDP Sciences 2003