Abstract
Crack nucleation due to the pile-ups of extrinsic grain-boundary dislocations around triple junctions is analysed. The analysis is based on a micromechanical model of interactions between the pile-ups and a triple-junction crack, and an approximate energy-based crack nucleation criterion. For a random microstructure of aluminium, the results show that the crack orientation, the crack length and the energy decrease due to crack formation have a rectangular, a skewed and a normal probability density distribution respectively. The effects of the remote loading state, the load magnitude and the mean grain size on the mean and standard deviation of the distributions are also quantified.