Simulation of deformation and fracture processes in nanocomposites

Alexander Vakhrushev,A.Y Fedotov

doi:10.3221/igf-esis.49.37

Abstract

The paper studies the processes of deformation and fracture in nanocomposites. The study was curry out by the method of mathematical modeling. The behavior of the nanosystem was described by the molecular dynamics apparatus. A modified immersed atom method was used as a potential. Demonstrated theoretical approaches to the study of the mechanical properties of nanocosposites and the processes of their destruction. Formulas for calculating the stress, strain tensors and displacement veare given. To maintain a constant temperature in the nanosystem, a Nose – Hoover thermostat was used. The destruction of nanocomposites was considered in the process of tension and shear deformation. Pure aluminum, a composite with an aluminum matrix and a filler in the form of spherical iron particles, and a composite with an aluminum matrix and a filler in the form of a cylindrical iron fiber were used as samples. After the filler was introduced into the nanocomposite, the sample was relaxed to ensure its more stable state. The simulation allowed us to establish the basic laws of changes in the atomic structure of the matrix and nanocomposite fillers during deformation and fracture. It is shown that the processes of deformation and destruction of nanocomposites substantially depend both on the structure and types of loading of the material. The results of the research can be used to study the processes of deformation of nanocomposite materials with promising functional properties.

Highlights

Nanocomposites are widely used due to their special properties, which better distinguish them from ordinary materials
The results of the research can be used to study the processes of deformation of nanocomposite materials with promising functional properties
The use of periodic boundary conditions made it possible to model the deformation and fracture of an “infinite” sample of a nanocomposite formed by the calculation cells along all coordinate axes

Summary

Introduction

Nanocomposites are widely used due to their special properties, which better distinguish them from ordinary materials. Comparison of characteristics was carried out with similar values obtained at temperatures close to normal The authors explain these differences by nanoscale plasticity and internal resistance of the atomic crystal lattice of the sample material. Special attention is paid to the behavior of various mechanisms of plastic deformation depending on transitions between materials and on the grain size. Physical mechanisms in nanocomposites, such as sliding along the grain boundaries of a material, movement of crystal lattice dislocations, and processes of diffusion plasticity, are illustrated. The processes of deformation, fracture and formation of cracks are discussed taking into account the influence of the internal structure, the appearance and modification of defects, the size factor and the dislocation mechanisms of plastic deformation with respect to nanostructured materials. The work is a development and generalization of the earlier publications of the authors [2224], where the main attention is paid to the generalized macro characteristics of nanoparticles and nanocomposites based on them as a whole

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Conclusion