文摘
Friction effects on the optimum shape design for a normal impacting, rigid body are investigated and the optimum 3D- nose shapes of rods are proposed for deep penetration into soil, concrete and metal media. The study is conducted by assuming that the normal and tangent stresses, that act on the impactor nose, are of the Poncelet and Coulomb forms, respectively. The geometrical characteristics of the shapes maximizing penetration depth are compared with those of the minimal resistance bodies obtained at the initial stage of the penetration event. When mass, shank radius and nose length of the rods are fixed, a comparative study of the penetration depths of the optimal impactors and impactors with conical and ogival nose shapes is carried out. The conditions, when the benefits of the optimal configurations in providing deep penetration into soil, concrete and metal media become significant in comparison with other shapes, have been obtained. The model parameters are taken from the published reports on penetration data obtained for striking velocities to 1.5 km/s while the impactors remained rigid and visibly undeformed.
