Study on the behavior of projectile shank friction penetrating into concrete

A resistance model for the kinetic energy penetrator with two different friction coefficients on its nose and shank respectively is presented based on the dynamic spherical cavity-expansion theory of the concrete materials. The effects of the shank friction on the depth of penetration and acceleration curve were investigated, and the composition of the penetration resistance under different striking velocities was investigated too. The results show that, for the ogive-nose projectile with CRH of 3 and length-diameter ratio of 7 penetrating into the 45 MPa concrete, when the initial velocity is in the range of 800~1300 m/s, an error of at least 10% on the penetration depth would occur if the shank friction is neglected. During the penetration process, the proportion of the shank friction in the total resistance is increasing all the time. Meanwhile, the target inertial term of the penetration resistance can't be neglected anymore at this velocity range. When the initial velocity of the projectile is less than 400 m/s, the effects of both the friction and target inertial term on the depth of penetration can be neglected.