Correlations between fractal characteristics in the bulk and on the surface of a deformable solid as an indicator of critical state precursors of the material

In this study, the evolution of fractal characteristics on the surface and in the bulk of a solid, which have been obtained during uniaxial deformation of copper and nickel, is demonstrated experimentally. The intervals of their mutual linear correlation are established. In addition, in the discussion of experimental results, a hypothesis is proposed, in which a quite unambiguous physical meaning of the fractal dimension as an independent indicator of the degree of strain localisation depending on two physical parameters (average dislocation density and local dislocation density) is formulated.