The penetrometer and soil exploration. Interpretation of penetration diagrams — Theory and practice

Abstract

The high-speed projectile often has significant mass loss and nose blunting when it penetrates into the concrete target, which usually decreases the penetration performance of projectile. A shape-evolvement model is constructed to predict the shape evolvement and penetration performance of projectile in the present manuscript. The penetration process and projectile are respectively discretized in the temporal and spatial dimensions. The shape evolvement is obtained by the projectile outer surface receding point by point. During a discrete time step, the governing equation is derived for the receding displacement based on the thermal mechanism of mass loss. The related friction work between the projectile and target is obtained based on the energy conservation law, which avoids the determination of the specific form for friction. The model is validated by the experimental results. Furthermore, two suggestions are provided to reduce the projectile nose blunting by distributing the refractory material in the projectile nose. Both schemes achieve the prescribed aim and then enhance the penetration performance of the projectile. Finally, the underlying assumptions in the model are analyzed, and the possible reasons are discussed for the deviation between the model prediction and the experimental result.