Inherent damage zone model for strength evaluation of small fatigue cracks

Abstract An inherent damage zone model is presented to explain the fatigue properties of small sized cracks near the fatigue limit and the crack growth threshold. A special feature of the paper is using the exact stress distributions of notched and cracked specimens at the strength evaluations. Analytical elastic solutions by Neuber and Westergaard are employed for this purpose. A crack propagation law is newly developed based on the inherent damage zone model, and the propagation properties of small sized cracks and the mechanism of non-propagating crack are discussed based on the model. The estimated propagation rates of small sized fatigue cracks, the crack size effect on threshold strength and the occurrence condition of non-propagating crack in elliptic notches and circular holes show good agreements with the previous experimental results.

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