Regularities of fatigue fracture of metal materials

摘要

The unique criterion of cycle fracture of metal materials is obtained and on its basis the existence of unique fatigue curve in all range of cycles loading (low-cycle and high-cycle fatigue) for a stage of crack initiation and stage of crack propagation is shown. The criterion allows on the extreme saved damage to calculate durability of elements of constructions, and also levels of the accumulated damages for any stage of loading. This criterion is independent of the type, structural state (i.e., treatment), form of a loading, of a material (single-frequency, double-frequency, asymmetric, having time lags, and programmable), as well as, of the loading conditions (temperature, frequency, type loading). Unique criterion and unique curve of fatigue are proved by numerous experimental data for different metal constructional materials and various conditions of loading. New approaches that can be applied to both the calculation methods for the cycle strength and to the rules for the choice of structural materials are proposed.