Impact of blunted bodies on a liquid or elastic medium

Abstract

The impact interaction between a solid body and a liquid or elastic half-space and between two elastic bodies is analyzed. The main approaches and representative numerical results are set out.Introduction. The present review analyzes and generalizes the results from studies of the interaction between a body and a liquid, a body and an elastic medium, and between two deformable bodies, which are originally undeformed and come into contact at some initial moment. We will consider an impact of blunted bodies, namely, the initial stage of penetration of bodies with a smoothly curved surface into a medium. By penetration is usually meant a set of mechanical phenomena accompanying an impact of a moving body on the surface of a medium, followed by immersion into it. The forces of resistance exerted by the medium on the body are, as a rule, much greater than the forces that move the body prior to the impact. Penetrating bodies, especially those with the frontal part blunted, usually suffer maximum loads at the early stage of penetration. In this connection, it is important to analyze the impact interaction of penetrating (colliding) bodies and structural members.Solid-fluid impact theory came to be developed intensively in the 1930s of the 20th century in connection with water-landing studies. Later, similar studies were conducted in shipbuilding (slamming of high-speed vehicles), in new branches of mechanical engineering (impact of solids or liquid particles on structural members), in space engineering (splash-down (landing) of descent modules), etc. The general problem of impact of a body on a liquid (medium) is extremely complex, since the penetration process is accompanied by a variety of phenomena such as large strains of the body and medium, breaking of the medium surface, splash and jet formation, discontinuous flows, entrainment of the air space, cavitation, moving unknown boundaries, etc. The complete nonlinear analysis of the penetration of a structural member into a liquid is hardly feasible. Therefore, common practice is to isolate the most significant aspects from the general formulation of the problem, leaving less important factors aside. Note that we do not address numerical methods here (they are discussed, e.g., in [2]).Historically, there are several approaches to the problem in question. The earliest approach is to consider the medium as a perfect incompressible liquid. The first approaches due to Von Carman and Sedov, which helped to solve many applied problems, described the process globally. However, a researcher or an engineer often needs to know not only integral but also other characteristics such as contact pressure, stress-strain state at some (frontal) points or in the whole body, liquid velocity fields, etc. In this case, the problem needs a more rigorous formulation. One was proposed by Wagner [98] (modeling penetration as an impact on a floating rigid plate) and used as the basis for many research projects. Logvinovich [67] established the applicability limits for Wagner's theory, solved t...

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