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.

A PD simulation-informed prediction of penetration depth of rigid rods through materials susceptible to microcracking

“…The obvious importance of the sliding friction on the penetration depth is discussed from the very onset of the penetration studies [3] to the present [34,35]. These deliberations are to this day hampered by lack of experimental techniques that can quantify the frictional phenomena at the high sliding velocities.…”

Minimum drag and heating 0.3-caliber projectile nose geometry

“…The purpose of the current investigation is to employ the computational fluid dynamics (CFD) technique to determine the drag and the heat transfer characteristics on a nose shape previously discussed by Schinetsky et al., 1 Olcmen et al., 2 Holland et al. 3 The research focuses on comparing the aerothermal performance of different geometries within the supersonic velocity range.…”

“…That work was then expanded to find nose shapes that would result in maximum penetration including the viscosity effects. 2…”

“…The purpose of the current investigation is to employ the computational fluid dynamics (CFD) technique to determine the drag and the heat transfer characteristics on a nose shape previously discussed by Schinetsky et al, 1 Olcmen et al, 2 Holland et al 3 The research focuses on comparing the aerothermal performance of different geometries within the supersonic velocity range. In the previous investigation, 1 a new shape was defined based on the optimization to achieve the least nose factor, N, using the penetration mechanics theory, where the viscous effects were omitted.…”

“…That work was then expanded to find nose shapes that would result in maximum penetration including the viscosity effects. 2 Penetrator nose geometry has a prominent role in penetration mechanics as well as in the aerodynamic characteristics of the penetrators. Hill 7 presented an analytical estimate to assess the effect of ''headshape'' (nose shape) on the rigid penetrator performance in thick targets.…”