Interpretation of Plasticity Effects Using the CJP Crack Tip Field Model

Abstract

<jats:p>This paper will outline the development of a model of crack tip fields that represents an innovation in incorporate the influences on crack tip displacement and stress fields of the zone of local plasticity that envelops a growing fatigue crack. The model uses assumed distributions of elastic stresses induced at the elastic-plastic boundary via wake contact and compatibility requirements, and defines a set of modified elastic stress intensity factors to characterise the crack stress or displacement tip field. In particular, recent work will be presented that compares the interpretation of plasticity-induced shielding obtained from trends observed in K<jats:sub>R</jats:sub> and K<jats:sub>F</jats:sub> with values of so-called ‘crack closure’ obtained via traditional strain gauge determination.</jats:p>