MODELING OF THE FATIGUE DURABILITY OF STRUCTURAL ALLOYS UNDER TWO-FREQUENCY LOADING

The processes of fatigue life polycrystalline structural alloys under the combined action low- and high-cycle mechanisms are considered. From standpoint damaged medium mechanics (DMM), a mathematical model has been developed that describes plastic deformation accumulation damage. DMM consists three interrelated parts: relations determine cyclic elastoplastic behavior material, taking into account dependence on fracture process; equations describing kinetics damage accumulation; criterion for strength material. Variant constitutive elastoplasticity is based concept microplastic loading surface in von Mises form principle gradient strain rate vector to at point. This version state reflects main effects process material arbitrary complex trajectories. A variant kinetic introduction scalar parameter, energy principles takes formation, growth fusion microdefects conditions. unified evolutionary equation damages low-cycle proposed. As condition reaching critical value used. To assess reliability limits applicability DMM, numerical studies by inelastic failure steel 20 08Х18Н12Т were carried out single-frequency upper frequency two-frequency with different amplitude ratios. And comparison obtained results data field experiments out. comparing calculated experimental showed environment reliably durability structures mechanisms.