Regularities of variation of spherical tensor in crystals of polycrystalline material under torsion action

Abstract

The laws of fluctuations of spherical stress tensors in cubic lattice crystals are investigated in function of their orientation in polycrystalline single-phase materials. It is shown that interactions among crystals in conglomerate of polycrystals lead at local volume stresses/strains appearance even at pure macroscopic shear. The interval of changing of spherical stress/strain tensors is comparable with macroscopic module of deviator of stresses/strains and depends on anisotropy coefficient of crystals. Based on established laws it is possible to explain the row of experimental thermo mechanical effects, for example, energy dissipation which is connected with concept of internal friction. According to this model the conditions of destructions of polycrystalline materials could be described at general load using at local level simple strength criteria’s: maximum normal stress/strain.