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Propagation of Hypervelocity Impact Fragment Clouds in Pressure Gas

: Schäfer, F.; Schneider, E.; Lambert, M.; Mayseless, M.


International Journal of Impact Engineering 20 (1997), S.697-710
ISSN: 0734-743X
Fraunhofer EMI ()
aluminium projectile; bumper plate; crater depth; fragment cloud; hypervelocity impact; pressure container; residual velocity

This study investigates the propagation of hypervelocity impact fragment clouds in pressure gas. Fragment clouds were generated through perforation of thin aluminium bumper plates by spherical aluminium projectiles. A thick aluminium backwall plate, placed inside a pressure container at a given distance from the bumper plate, caught the fragments to act as a witness plate for the residual damage potential of the fragments. Crater depth statistics are presented as a function of container pressure. The fragment cloud was photographed by means of an image converter camera. The images showed a strong deformation of the fragment cloud for increased container pressures and were used to extract residual velocities until up to 50 mu s after impact. The deceleration of the velocity as a function of time after impact suggested an exponential decay function as the best fit to the curve. Thus, maximum fragment impact velocities on the backwall plate could be extrapolated from the axial cloud veloc it ites. The extrapolated cruves were compared with experimental time-of-flight measurements, and proved a good match. Fragment impact velocities and maximum crater depths were used to calculate maximum fragment particle sizes as a function of the container gas pressure.