Resistance of Dry and Partially Saturated Sand to Rapid Ordnance Penetration Using Photon Doppler Velocimetry: Fid-Bau Portal

Resistance of Dry and Partially Saturated Sand to Rapid Ordnance Penetration Using Photon Doppler Velocimetry

Giacomo, Louis / Dinotte, Joseph / Omidvar, Mehdi

Results of experiments involving rapid impact and penetration of projectiles in sand targets are presented. A vertical firing range is used to launch aluminum rods having a diameter of 14.3 mm and a length-to-diameter ratio of 5.3 at an impact velocity of approximately 150 m/s into dry and partially saturated sand targets prepared at precise densities. Very loose and very dense sand targets are prepared by means of dry pluviation. Direct measurements of penetration velocity-time history are obtained using a photon Doppler velocimeter (PDV). The results of the experiments reveal that penetration resistance exhibits two regimes in dense sand, separated by a transition velocity of approximately 45 m/s. Furthermore, it is observed that saturation affects penetration differently at high velocities compared to low velocities. High-velocity penetration of partially saturated dense sand is accompanied by cavitation, which reduces the role of the pore fluid in penetration resistance. At lower velocities, penetration into partially saturated sand produces negative pore water pressures, resulting in an increase in penetration resistance. These observations are used to develop a phenomenological framework for predicting the depth of burial of high-speed projectiles in sand.