AN ANALYSIS OF 2 MODELS OF SUPERDEEP PENETRATION

Super-deep penetration can be characterized as the fast motion of a pr ojectile in a solid material at distances hundreds and thousands of ti mes greater than the characteristic initial diameter of the projectile . In the present paper, some experimental data on the super-deep penet ration of some microparticles by the hypervelocity impact of micropart icle clusters are provided, and one theoretical problem of super-deep penetration is then investigated under two different simplifying assum ptions about a medium (elastic solid and compressible fluid). The pene trator is modeled as an absolutely rigid, smooth, thin plate, that cut s the material by its nose, leaving a cavity and moving steadily at su bsonic speed under a small angle of incidence. The plate is considered to touch the material on only one side, while the other side remains free. The drag against the fast penetrator in an elastic solid and com pressible fluid is analyzed using the exact solution to the problem fo r these media. In the limiting case, the solution equations for fluid coincide with the corresponding equations of the classic problems of R ayleigh and Chaplygin. Distribution of the contact pressure along the plate, and hence the drag, appear the same in both models, with the ex ception of the factor depending on the Mach number and the physical pr operties. At the Rayleigh speed in an elastic medium, the drag and con tact pressure on the penetrator vanish. A self-propagating solitary wa ve (introduced earlier by the author and called the rayleighon), inclu ding a cavity and projectile moving therein without drag, is found. An analysis of the referenced solution, obtained in the present paper, h as proven that a rayleighon can be formed in an elastic medium in the process of acceleration of a thin penetrator, up to the Rayleigh speed . Therefore, the results of the paper support the idea that super-deep penetration can be discerned as the self-propagation of a rayleighon. It is concluded that the solutions analyzed provide some hints for or ganizing future (expensive) tests to experimentally discover a rayleig hon. A section containing some details of the mathematical calculation s is appended to the paper.