Investigation of initiation conditions of relative displacements of the fault-block media units under vibration loading

On the basis of computer modeling by the method of movable cellular automata the theoretical investigation of initiation conditions of relative displacements along the interfaces of complex stressed geological media blocks in the complex intense condition under local vibrating loading has been performed. It is shown, that defining factors at formation of unstable shift on the interblock border of fracture-block geological environments are the relative value of shift stresses and also the frequency of vibrating loading, i. е. time of impulse energy allocation. Low in power, but long-continued loadings on influences on high-voltage borders of section are the most effective in respect to power inputs

Development of a formalism of movable cellular automaton method for numerical modeling of fracture of heterogeneous elastic-plastic materials

A general approach to realization of models of elasticity, plasticity and fracture of heterogeneousmaterials within the framework of particle-based numerical methods is proposed in the paper. It is based onbuilding many-body forces of particle interaction, which provide response of particle ensemble correctlyconforming to the response (including elastic-plastic behavior and fracture) of simulated solids. Implementationof proposed approach within particle-based methods is demonstrated by the example of the movable cellularautomaton (MCA) method, which integrates the possibilities of particle-based discrete element method (DEM)and cellular automaton methods. Emergent advantages of the developed approach to formulation of manybodyinteraction are discussed. Main of them are its applicability to various realizations of the concept ofdiscrete elements and a possibility to realize various rheological models (including elastic-plastic or visco-elasticplastic)and models of fracture to study deformation and fracture of solid-phase materials and media.Capabilities of particle-based modeling of heterogeneous solids are demonstrated by the problem of simulationof deformation and fracture of particle-reinforced metal-ceramic composites

Development of a formalism of discrete element method to study mechanical response of geological materials and media at different scales

A general approach to realization of models of elasticity, plasticity and fracture of heterogeneous materials within the framework of particle-based discrete element method is proposed in the paper. The approach is based on constructing many-body forces of particle interaction, which provide response of particle ensemble correctly conforming to the response (including elastic-plastic behavior and fracture) of simulated solids. For correct modeling of inelastic deformation and failure of geological materials and media at "high" structural scales (relative to the scale of grains) an implementation of dilatational Nikolaevsky's model of plasticity of rocks within the framework of mathematical formalism of discrete element method is proposed. Perspectives of multiscale modeling of geological materials from grainrelated scale up to macroscopic scale within the same numerical technique (DEM) are discussed

Features of interface formation in crystallites under mechanically activated diffusion. A molecular dynamics study.

In this paper, we carried out investigation of behavior of the material under loading condition identical those used in FSW using molecular dynamic method. The loading was modelled by a rigid rotating “tool” that movies along boundary between two grains. We considered pairing of two crystallites of copper, crystallites of copper and iron, and two crystallites of aluminum 2024. Analysis of the structure of the sample showed the intermixing and stirring of dissimilar atoms as a result the FSW tool pass at the inter-crystallite boundary. It was shown, that under certain condition of loading when tool passes there a region where atoms can occupying the original position of the crystal lattice. We also show influence of an additional oscillating impact applied to the moving tool on the structure of the resulting weld. The simulation results obtained can be used for understanding the processes realized under mechanically activated diffusion

The Effect of Volume Fraction of Δ-Ferrite on Hydrogen Embrittlement in High-Nitrogen Austenitic Steel

The effect of volume fraction of δ-ferrite and the density of interphase (austenite/δ-ferrite) and grain (austenite/austenite) boundaries on the mechanical properties and fracture mechanisms of a high-nitrogen austenitic steel before and after hydrogen electrolytic charging for 100 h was investigated. An increase in the density of interphase and grain boundaries and decrease in fraction of δ-ferrite increase the resistance of steel against hydrogen embrittlement.Было исследовано влияние объемной доли δ-феррита и плотности межфазных (аустенит/δ-феррит) и межзеренных границ (аустенит/аустенит) на механические свойства и механизмы разрушения высокоазотистой аустенитной стали до и после электролитического наводороживания. Увеличение плотности межфазных и межзеренных границ и уменьшение доли феррита приводит к повышению устойчивости стали и водородному охрупчиванию.Работа выполнена при финансовой поддержке Российского научного фонда (грант № 17–19–01197)

Development of a formalism of discrete element method to study mechanical response of geological materials and media at different scales

A general approach to realization of models of elasticity, plasticity and fracture of heterogeneous materials within the framework of particle-based discrete element method is proposed in the paper. The approach is based on constructing many-body forces of particle interaction, which provide response of particle ensemble correctly conforming to the response (including elastic-plastic behavior and fracture) of simulated solids. For correct modeling of inelastic deformation and failure of geological materials and media at "high" structural scales (relative to the scale of grains) an implementation of dilatational Nikolaevsky's model of plasticity of rocks within the framework of mathematical formalism of discrete element method is proposed. Perspectives of multiscale modeling of geological materials from grainrelated scale up to macroscopic scale within the same numerical technique (DEM) are discussed