The relevance of the issue of strength and durability of structures every year only increases, which is due to both the increase in their load and the use of new structural materials. With the development of fracture mechanics, the problem of operation of structural elements with cracks is considered from new positions allowing in some cases to consciously continue the operation of the object. This is made possible by a deep understanding of the nature and mechanisms of fatigue failure. In this paper the kinetics of macrocrackunder irregular loading is considered depending on various factors on the basis of the classification proposed by Skorupa. The results of numerous studies for samples of various structural materials during their testing, both single and block overloads of different signs are observed. The basic laws of macrocrack kinetics under irregular loading are established, the difference in crack behavior after tension and compression overload is noted. Experimental data on the influence of the asymmetry coefficients of loading cycles and the magnitude of the stress intensity factors under basic loading and overload cycles on the subsequent crack growth are presented. Of particular interest is the effect on the fracture kinetics of various possible combinations and sequences of stress and compression overload cycles.
macrocrack, overload, crack growth rate, stress intensity factor
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