A mechanistic modelling methodology for microstructure-sensitive fatigue crack growth

Microstructure-interacting short crack growth in blocky alpha Zircaloy-4

“…The studies revealed that intragranular single crystal fatigue crack growth along prism slip planes could give rise to oscillating 'zig-zag' paths as the cracks grow in to the previously strained but uncracked regions. The key crystallographic orientation giving rise to this is that in a grain in Sample A considered above which shows intragranular crack path change in good agreement with the model results in [34]. Other crystal orientations leading to prism slip lead to intragranular crack growth but without oscillations.…”

The dislocation configurational energy density in discrete dislocation plasticity

“…A quantity determined at the crystal plasticity length scale, but motivated by the idea that fatigue crack nucleation may be driven by dislocation configurational energy, was recently introduced and demonstrated to predict the fatigue crack nucleation sites in a range of alloys at the microstructural length scale [4,6,48] and to capture the microstructural sensitivity of fatigue crack growth [35,49,50]. Termed the stored energy density, this quantity assumed a small fraction (typically 5%) of the plastic work was stored in the form of dislocation structures (and hence the link to dislocation configurational energy) over a length scale given by the dislocation mean free distance, thus providing a local energy area density, given by = � :…”

Cracking simulation‐based fatigue life assessment

“…In recent studies of fatigue cracks as small as 10 μm in length, anomalous propagation behavior has been observed when comparisons were made with corresponding long crack behavior . Short FCG rates usually exhibit intermittent periods of both acceleration and deceleration.…”