Aniskovich

A mathematical model of deformation of flexible armored materials based on aramid fabric under high-speed effects was proposed. The model takes into account the following peculiarities of deformation parameters of composite materials of the specified class: possibility of deformation without destruction at finite deformations, a considerable difference between stress-deformation diagrams under tension and under compression, dependence of these diagrams on a loading rate, pseudo-plastic features of materials caused by pulling out threads from fabric and/or a plastic character of deformation, anisotropy of nonlinear-elastic and visco-plastic properties and other effects. A problem statement was formulated for dynamic deformation of flexible armored materials. In order to solve the problem in a two-dimensional case the method of band-adaptive grids was applied. An example of numerical solution of the problem was presented for a high-speed action of a striker onto a flexible armored material; some effects of deformation of materials of the specified class were analyzed.

Using a multi-scale homogenization method, a three-level model was developed for ceramic composite materials based on the reaction-bonded SiC. Numerical simulation was performed with the use of the finite-element method for solving a set of local problems over the periodicity cells of three structural levels. Tensor fields of stress concentration were computed in matrices and fillers. A new strength criterion of a matrix and fillers at multi-axis stress state was applied; this criterion takes into account a significant difference (more than ten times) between strength features of ceramics under tension and compression. A model that takes into account a scale effect of the strength of ceramic composites was proposed. Numerical investigation of sequential microstructural destruction of ceramic composites up to the final fracture was conducted. Computations demonstrated that at the presence of a polydisperse structure of ceramics, a change in concentrations of large-scale fractions plays less considerable role than in the case of small particles fraction.