ИСТИНА

Abstract: A phenomenological model of brittle fatigue fracture of metals and alloys at proportional loading is presented. The model is constructed within the framework of the physical-mechanical approach as a system of hypotheses about the probability of defect growing on different scale structural levels (such as brittle micro- and macro cracks). From the whole scale hierarchy here is considered six scale structural levels in accordance with the stages of the metal structure evolution and different physical mechanisms. Here are formulated constitutive relations for the fracture probability at each level. The amplitude of the maximum principal stress is selected as a variable of these relations, and the material functions are determined on the results of fatigue tests at symmetric uniaxial and biaxial loading and shear and take into account the principal stress relations according to known fatigue strength criteria of metals. Here were obtained fatigue curves on each of six defect levels and fatigue macro crack formation curves for proportional tension - torsion loading and biaxial loading with different amplitude ratios. It is shown the correlation between calculated and experimental data. Acknowledgements: the work is financially supported by the Ministry of Education and Sciences of the Russian Federation within the federal target program "Development of physical and mechanical foundations and methods for complex system calculation in solid mechanics at thermo-mechanical loadings"(No. AAAA-A16-116071210055-5).