On the effect of the release of residual stresses due to near-tip microcracking

Abstract

This article provides a comprehensive theoretical treatment of the interaction effects associated with the release of a general residual stress field as a result of the formation of microcracks in the vicinity of a main crack. The theoretical formulations are based upon the use of the complex potentials of Muskhelishvili and an appropriate superposition procedure. The induced stress intensity factor at the main crack is obtained in a series form and the leading order closed form solution was utilized to elucidate two interesting features of the study. The first is concerned with shielding and amplification effects associated with the release of a uniform residual stress field from a single microcrack. The second is concerned with shielding effects due to the formation of a microcracking zone in the vicinity of a stationary and a steadily growing main crack. The results for the case of a single microcrack reveal that, depending upon the location and orientation of the mirocrack, shielding and amplification effects may become prevalent. In the case of a microcracking zone, equivalence between the current interaction model and the contiuum mechanics approach was established based upon similar microcrack nucleation criteria.