MATHEMATICAL MODELING OF SCALE-STRUCTURAL FAILURE AT PROGRAM CYCLIC LOADING OF METALS AND ALLOYS

Relations for the failure probability at the micro-, meso-, and macrolevels and fatigue curves on defect levels at the program loading are proposed. The results of calculations for 0,25 % carbon steel at the loading of two or three blocks with different amplitudes and cycle numbers, steel 45 with different distributions of stress amplitudes and titanium alloy TC21 at symmetric loading, each block of which consists of two amplitudes of different numbers of cycles are discussed. For the materials considered, the model describes the evolution of brittle failure and the fatigue curve on fracture at symmetrical loading well. The scope of applicability of the model for program loadings is determined. It well describes the fatigue curve on fracture in a range of