On the Kinetics of Elastoplastic Growth of Through Fatigue Macrocracks in Metals under Extreme and Natural Operational Conditions

Author： Pinyak I. S.

Publisher： Springer Publishing Company

ISSN： 0039-2316

Source： Strength of Materials, Vol.36, Iss.2, 2004-03, pp. : 203-212

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Abstract

The relationship between the empirical parameters \C_1 and \C_2 established earlier by the author makes it possible to avoid the necessity of conducting, under extreme and natural conditions, of a complex experiment aimed at the evaluation of the effective characteristics of cyclic crack-growth resistance of a structural material and the upper bound \DELTA K_{fcl, X} of growth of a through fatigue macrocrack in the presence of crack-tip closure. The results of the basic tests performed to determine the nominal effective characteristics of cyclic crack-growth resistance and the indicated relationship reliably describe the kinetics of growth of macrocracks in the entire range of the kinetic diagram of fatigue fracture with the help of an equation taking into account the regularities of its behavior in a broad range of action of various factors under extreme and natural conditions and in the presence of crack closure. Under the indicated conditions, we determine the durability of the material of a cracked element and its dangerous limiting state. The analysis of the kinetics of growth of a through fatigue macrocrack shows that the stability of its propagation is guaranteed by the presence of residual compression stresses along its lips.