Integration of Statistical and Physical Models of Short Fatigue Crack Growth

摘要

The probabilistic analysis of the propagation of small fatigue cracks has been investigated. Monte Carlo simulations have been formulated that can embrace nearly all details of the micromechanics of small crack growth. They calculate the propagation of the entire, irregular crack front as it passes through a random microstructure. The simulations illuminate both the mechanics and the statistics of small crack growth. A computationally efficient probabilistic model has also been formulated as the basis of lifetime prediction in field application. The probabilistic model is sufficiently flexible to allow incorporation of the physical aspects of propagation that have been shown in the Monte Carlo simulations to be necessary for accurate predictions. In particular, the probabilistic model begins with the premise that two independent variables, for example but not necessarily the crack length and the crack shape, are required to account for the observed statistics of growth. (jes)