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The phenomenon of stable crack growth in brittle materials is considered where stable crack growth is modeled as the formation of an elongated process zone of microcracks and isolated intact ligaments ahead of a stationary main crack. The role of residual stress in protecting the intact ligaments is explored via the hypothesis that compressive zones surrounding isolated ligaments under residual tension protect these ligaments and result in stable crack growth and toughening of the microcracked material. The dependence of process zone behavior on either a plane strain or an axisymmetric representation of microcrack distribution is considered. Numerical results based on the above hypothesis indicate that interaction between residual stress and microcracking can lead to stable crack growth with attendant toughness enhancement.

The phenomenon of stable crack growth in brittle materials is considered where stable crack growth is modeled as the formation of a bridge zone in the wake of a stably propagating main crack. The hypothesis that compressive zones surround and protect isolated ligaments under residual tension, which then leads to stable crack growth with attendant toughness enhancement, is incorporated into the bridge-zone formulation. Effects associated with debonding of ligaments on stable crack growth are explored via a simple treatment of microcrack branching. Similarity between the present bridge-zone description and a previously developed process-zone description of stable crack growth is quantitatively established. The importance of interpreting experimentally determined resistance-curve data subject to K-dominance requirements is highlighted by comparison of model predictions with select data in the literature.

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