ABSTRACT
Cyclic loading is one of the varieties of the force field. Differential form of the thermodynamic equation of state (Section 2.4) makes it possible to derive an equation for thermodynamic fatigue (Section 7.2),. that relates the number of loading cycles (known also as cyclic fatigue life) to working parameters of the alternating force and thermal fields. It also characterizes mechanical fatigue at constant temperature and thermal fatigue in constant force fields. Comparison of theory and experiment yields good coincidence. Section 7.3 shows that the physical nature of fatigue is in the active occurrence of compresson-dilaton phase transitions (following the diagram in Figures 1.15) under thermal insufficiency at alternating deformation. This stimulates formation of the flow of failures of interatomic bonds at the Debye temperature.
