22. A Heterogeneous Medium Model and Its Application in a Target Perforation Problems

The cermet composite is considered as a mixture of solid materials with a given volume concentration and joint deformation of the components. The REACTOR software package developed at the Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences (ITAM SB RAS) is used for the modeling. Various approaches to the prediction of elastic–plastic characteristics, such as elastic moduli and yield strength, describing the behavior of heterogeneous materials, are considered. It is shown that the mixture rule, which approximates the value of elastic sound velocities from the volume concentration of the components, proved itself well for the calculation of elastic moduli, while the yield strength must be calculated through the mass concentration. The proposed model of heterogeneous medium has been applied to solving a number of problems on the resistance of heterogeneous and gradient barriers to impact by a hardened striker. For barriers from various combinations of mild steel and Al₂O₃ ceramics at equal volume concentrations, ballistic curves of their resistance to impact of a solid steel core are constructed. It is shown that a layered barrier, consisting of equal in volume plates of Al₂O₃ ceramics and steel, is more resistant to impact by a solid core in comparison with other cermet barriers. In a numerical experiment, it has been found out that heterogeneous and gradient barriers have an advantage over a two-layer barrier (B₄C ceramics + steel) in the range of encounter velocities exceeding 650 m/s. A series of 2D and 3D calculations for modeling the perforation of heterogeneous barriers has been performed. It is shown that the resistance of heterogeneous barriers to perforation by a solid striker is approximately at the same level. The heterogeneous model of ice has made it possible to explain the anomalous dependence of the depth of the cavity in ice on the speed of impact with a steel cylinder, which was discovered.