Characterization of fatigue crack growth with the configurational force concept

How can fatigue crack growth be correctly characterized in presence of significant plastic deformation? A well-known approach is to apply the experimental cyclic J-integral ΔJ^exp. However, the application of ΔJ^exp is questionable, since it presumes, like the classical J-integral, deformation theory of plasticity, which is not applicable for cyclic loading and crack extension. This book presents the physically correct characterization of fatigue crack growth in elastic-plastic materials by using the incremental plasticity cyclic J-integral ΔJ^ep, which is derived from the configurational force concept. New insights are obtained into longstanding questions: Is the application of ΔJ^exp correct? What is the most important mechanism for crack growth retardation after an overload? It is shown that ΔJ^exp equals ΔJ^ep only for the limiting case of a non-propagating fatigue crack. In general, care should be taken when using ΔJ^exp since it can lead to a non-conservative assessment of the fatigue lifetime.