Characteristics of Development of Fatigue Cracks in Steel under Low-Level Operation Loading

An assessment method for characteristics of low-rate development of fatigue cracks under operational loading is proposed. The method is based on the decrease in the irregular loading level by conservation of its conformity during crack growth. The control factor of the loading decrease is the intrinsic increase in the compliance of a sample during crack growth by its fixed opening. The experimental dependences of the crack growth rate on the number of operation load blocks with a decrease in the loading level are obtained.