A numerical analysis of projectile nose geometry including sliding friction for penetration into geological targets

Abstract

Optimal axisymmetric penetrator nose shapes that result in most penetration under the effect of pressure-dependent Coulomb Friction are presented. The nose shapes were determined by dividing a circular cylinder into line segments and iteratively updating the combination of line segment slopes to generate the nose geometries that result in the most penetration. Analysis was conducted for five different penetrator velocities, [Formula: see text], 11 different friction coefficient values, μ, and 10 different nose shape factors, α. Calculations were also made on common nose shapes including a 3/4 power nose, AMNG model, a tangent-ogive nose, and a standard cone to show that the new nose shapes result in the highest penetration. Results show that while most of the optimal nose shapes are convex shapes, the nose shapes become concave at μ = 0.4 for [Formula: see text], μ ≥ 0.6 for [Formula: see text], μ ≥ 0.8 for [Formula: see text] at different α values. The nose shapes are also blunt in general except for [Formula: see text], while μ = 0.1, α = 0.3; μ = 0.2, α = 0.4; μ = 0.5, α = 0.6; for [Formula: see text], while μ = 0.2, α = 0.3; μ = 0.4, α = 0.4; for [Formula: see text], while μ = 0.1, α = 0.2; μ = 0.3, α = 0.3; μ = 0.7, α = 0.4; for [Formula: see text], while μ = 0.1, α = 0.2; μ = 0.4, α = 0.3; μ = 0.5, α = 0.3, where the nose shapes are more close to a cone. Results can be used to select a nose shape that can achieve the desired penetration depth.