Effect of Nose Shape on Long Rod Penetration Into Dry Sand

Flat, hemispherical and ogive‐2 nosed mild steel projectiles (10 mm diameter, 100 mm length) were fired at 200 m s−1 into the end face of cylindrically confined dry sand (100 mm diameter, 150 mm length). Projectiles were tracked through the sand using flash radiography and high speed photography. By seeding a horizontal plane of randomly dispersed lead shot (<1.5 mm diameter) across the centre of the cylinder, the displacement field induced by the impact was mapped using Digital Speckle Radiography (DSR). By imaging at successive time intervals, a temporal history of the penetration was generated. DSR reveals a cone of displacement emanating from the impact point in all cases, leaving areas unmoved during the early stages of penetration. The magnitude and extent of the displacement cone is observed to be greatest in the flat nosed case. Initial rapid deceleration is seen in all nose cases, relaxing to an approximately steady velocity as the projectile reaches the end of the target. Ogive nosed projectiles...