Search

A numerical analysis on impact response of multilayer plates and plates with a gradient substrate against steel projectile perforation was made. The shear strength was varied in the substrate within a certain range. The behavior of bodies is modeled by an elastic-plastic, porous, compressible medium, taking into account shock-wave phenomena and fragmentary fracture of materials. A numerical lagrangian method with modified node splitting algorithms was used. Good agreement between the computed and experimental results was obtained. During perforation, pattern of destruction of all plates has been investigated. The results show impact resistance of plates with a gradient substrate was greater than the homogeneous steel one, but less than multilayer ones. However, the impact resistance of multilayer plates is explained by the pinching effect of the layers.

A theoretical and experimental research of the behavior of ice destruction under shock and explosive loads was carried out. Full-scale underwater explosive experiments and laboratory impact experiments were performed. Especially to study the properties of ice with explosive loads, a mobile laboratory “Explosive Destruction of Natural Materials” was organized. The results of the full-scale experiment of the current year are given. Post-penetration analysis of destruction of three-layer ice targets with a low-velocity impact is presented. Briefly, the mathematical model of ice destruction under dynamic loads is described. The numerical method contains a new way for isolating discontinuity surfaces of materials. The impact of an ice cylinder on a rigid wall is modeled, which is considered as a quantitative test. The penetration of a metal container into thick ice is quantitatively described.

The impact response of unidirectional FGM is studied in detail. The behaviour of the material is described by the classical complex model of continuum mechanics. The calculations are performed in 2D axisymmetric approach using a modified Lagrangian method. The mathematical model and numerical method was developed at the Research Institute of Applied Mathematics and Mechanics of Tomsk State University. In the beginning, test calculations were carried out. The evolution of the destruction of homogeneous and FGM-samples, including the time of formation of the first foci of destruction, spall was studied. The time dependences of the velocity of the free surface, hydrostatic pressure, and the damage parameter were constructed. The presence of a graded substrate led to an increase in impact resistance at velocities up to 275 m/s.

In the present work, the process of interaction of ice impactors of spherical shape with targets of aluminum alloy and asbotextolite has been numerically investigated. The initial temperature of the impactors was set from 0 to 500° C. The speed of the impactors was set in the range from 500 m/s to 1500 m/s. The behavior of the medium was described from the general positions of the mechanics of continuous media and corresponded to modern concepts of the destruction of solids under load. The material was considered as isotropic, elastoplastic, compressible, porous medium. The equation of state is chosen in the Walsh form. The problem was solved in a two-dimensional formulation for the case of axial symmetry. The calculations were carried out using the Lagrangian technique of computer simulation, which takes into account the fragmentation of the material in shear and shear failure. The current configurations of the impactor-target and the velocity of the leading fragments are obtained when penetrating the targets.

In this paper, the problems deep penetration of compact impactors into the ice, taking into account different temperatures were solved. The behavior of ice is described by the basic system equations of continuum mechanics, i.e., the equations of continuity, momentum and energy in the lagrangian approach. Medium are compressible, isotropic, no mass forces, internal sources of heat and thermal conductivity. Medium also includethe shockwave phenomena, as well as formation “spall” and “shear” damage. The stress tensor is divided into deviatoric and spherical components. Equation of statewas chosen in the form of Walsh. The components of the stress tensor deviator located on the elasticplastic flow model based on the equations of Prandtl-Reis associated with von Mises yield criterion. Initial impactor velosity was varied atfrom 50 to 325 m/s. Numerical simulation results showed the influence of temperature of the ice to the depth of penetration of the impactors.

In the research, the behavior of ice under shock and explosive loads is analyzed. Full-scale experiments were carried out. It is established that the results of 2013 practically coincide with the results of 2017, which is explained by the temperature of the formation of river ice. Two research objects are considered, including freshwater ice and river ice cover. The Taylor test was simulated numerically. The results of the Taylor test are presented. Ice is described by an elastoplastic model of continuum mechanics. The process of explosive loading of ice by emulsion explosives is numerically simulated. The destruction of the ice cover under detonation products is analyzed in detail.