Wave generation under high-speed collision of a plate with a cone

Abstract

In this paper, results of experimental studies of wave generation in a contact melted layer under axial collisions of metallic plates with metallic bodies made in the form of truncated right circular cones are presented. In this case, a closed regular structure of the contact layer was formed for the first time as a series (train) of long waves on the exterior surfaces of copper and aluminum cones. It is found that the dependence of the measured wavelength on the group velocity corresponds to the rising branch of the wave dispersion law. The phenomenon of wave generation on contact layers in high-speed collisions of metallic bodies is studied for a long time. (We imply both fundamental studies, e.g., analysis of hydrodynamic instability of viscoplastic flows in contact melted layers in the collision zone and industrial applications, e.g., the plating and welding explosion technologies [1‐4].) Investigation of waves generated on the contact surface of metallic screens under high-speed collision with a body is important for the development of methods for efficient protection of objects in space against meteorite impacts. In a large degree, the interest in the process of wave generation is also caused by the possibility to study wave phenomena from the standpoint of general wave theory, as the contact layer is a medium in which the effects of dispersion and nonlinearity manifest themselves in full measure. These waves can be observed during and after a collision, and their shapes store information on the evolutionary stages of contact layers. Up to now, wave generation has been studied only for oblique incidence of flat plates when the collision angles are acute and strongly limited ( γ ≤ 20i ), whereas the wavelengths of the waves being produced are small ( λ ≤ 1 mm) and are determined by the capillary tension of the contact surface. In this case, as is known from [5], the dispersion law for the phase v p ( λ ) and group v g ( λ ) velocities of capillary waves are determined by diminishing branches of the dependences v p ( λ ) and v g ( λ ) . One more feature of colliding flat plates is the significant effect of their edges, which complicates the wave pattern. In this connection, it is of interest an advance into the region of large (even obtuse) collision angles and long wavelengths ( λ ♢ 1 mm). Then, wave generation is developed along the rising branch of the dependence v g ( λ ) , and boundary distortions of the wave pattern by virtue of the formation of waves with a closed wave front are excluded. The latter requirement can be provided in the case of collisions with a body of special geometric shape, in particular, with a rod [1]. In the present paper, we describe the results of our experimental studies of wave generation in a contact melted layer. We consider axial collisions of metallic plates with metallic bodies in the form of truncated right circular cones. In this case, a closed regular structure in the form of a series (train) of long waves was formed for the first time on the exterior surfaces of copper and aluminum cones.