Axial misfit stress relaxation in core-shell nanowires with hexagonal core via nucleation of rectangular prismatic dislocation loopsS.A. Krasnitckii, A.M. Smirnov, K.D. Mynbaev, L.V. Zhigilei & M.Yu. Gutkin
A theoretical model of axial misfit stress relaxation in core-shell nanowires with hexagonal cross section of the core through the nucleation of prismatic dislocation loops is suggested. Different nucleation sites of the loops in core-shell nanowires are considered. The energy change caused by the loop nucleation is calculated. The critical condition for the onset of the loops is given and analyzed in detail. The most favorable sites in nanowires and the optimal loop shape are...
The paper presents comparative numerical analysis of two ceramic materials subjected to impact loading. ZrO2(Y2O3) and Al2O3 ceramics are studied. The main objective of the work is to study influence of various material parameters on ballistic performance of ceramic materials and on characteristics of the dynamic fragmentation process. The applied numerical scheme is based on finite element method and incubation time fracture criterion. Results on fracture surface area, residual impactor velocity, fragment size distribution are...
On the correlation between multiscale mechanisms of deformation in uniaxial dynamic straining and high velocity penetrationYu.I. Meshcheryakov, G.V. Konovalov, N.I. Zhgacheva, A.K. Divakov & E.P. Osokin
In order to identify the successive stages of developing the hierarchy of multiscale mechanisms of dynamic straining, the shock-induced mesostructure formation is studied in combined experiments. Shock tests of two kinds of aluminum alloy, 1561 and 1565 alloys were conducted in parallel in two regimes of loading: (i) under uniaxial strain conditions and (ii) in high velocity penetration. Combination of loading regimes allows the correlation in formation of multiscale structure depending on strain rate and...
Employment of Eulerian, Lagrangian, and arbitrary Lagrangian-Eulerian description for crack opening problemE.A. Ivanova, D.V. Matyas & M.D. Stepanov
Numerical study of crack opening in the solid material of rock formation is presentedin this article. Initially introduced straight-line crack is widened by increasing internal pressure. The crack shape evolution resembles hydraulic fracturing and is considered as a transient process. Commercial code LS-DYNA was employed to obtain solutions by three types of descriptions, they are compared to the solution obtained in Eulerian description by a program based on the finite-volume method and written in Python...
A 3D finite element model has been developed for studying the ballistic behaviour of bi-layer ceramic-metal target plates under the impact loads induced by the projectiles of different diameter to length ratios. The bi-layer target constituted of alumina 95, as front layer, backed by aluminium alloy 2024-T3 layer, has been impacted by steel 4340 blunt and ogival nosed projectiles of diameter to length ratios, 0.5 and 1.1. The constitutive behaviour of ceramic was modelled using...
Surface growth of solids includes a wide variety of processes starting from additive manufacturing technologies and ending with plenty of biological problems. Model of surface growth based on the expression of the configurational force, derived from fundamental laws and entropy inequality, is offered in the present paper. A new expression for the configurational force called surface growth force, which controls growth and resorption, is used. Analysis of the applicability of the developed model was carried...
The mode of the serrated deformation is investigated mathematically in framework of the thermoactivation model of unstable plastic deformation in metals at low temperatures. The obtained solutions in the framework of known models, however, do not fully correspond to experimental situation, as the stress oscillations in reality are usually irregular and inhomogeneous. By this reason, additionally, the elastic correlations of neighboring deformation zones were taken into account in the model. Numerical analysis model showed that...
An asymptotic representation is obtained at large times for the thermal wavefront propagating in a one-dimensional harmonic crystal. The propagation of thermal waves from a localized thermal perturbation and the transition zone between regions with different temperatures is considered. An explicit solution is given for a number of the simplest forms of the initial temperature distribution. It is shown that during the wave evolution, the wavefront smoothes, e.g., for a power-law dependence its degree increases...
Institute of Problems of Mechanical Engineering8
Peter the Great St. Petersburg Polytechnic University4
Saint Petersburg State University2
Indian Institute of Technology Roorkee1
University of Virginia1
Indian Institute of Technology Delhi1
Central Research Institute of Structural Materials Prometey1