Hypothesis of Local Zones with Dependent Fatigue Damages Accumulation
It is set on results the conducted experiments, that the appearance of multiple of fatigue cracks on specimens and design units with numerous concentrators takes place stochastically dependently. This stochastic relationship, both positive and negative, is observed in some zone, with certain dimensions. Positive cross-correlation relationship supposes that before there the fatigue crack will have been originated, the early the subsequent crack will be found out in direction perpendicular to the applied force. Such sequence of fatigue cracks’ originations assumes a mode as a propagation of the first crack, converting it to the only main spread out one. Such zone can be examined as a separate specimen or desigh element with probabilistic descriptions of endurance, fatigue strenght and other characteristics of reliability, that determines reliability of whole system. A physical proof of such zones existence and the description of reliability characteristics are shown as mathematical models.
A. Urbahs et al., "Hypothesis of Local Zones with Dependent Fatigue Damages Accumulation", Applied Mechanics and Materials, Vol. 232, pp. 19-23, 2012