NUCLEATION OF SPLITTING CRACKS IN COLUMNAR FRESH-WATER ICE

Under across-column uniaxial and biaxial compression loading of column ar ice polycrystals in the brittle regime, a set of cracks that split the columnar grains has been observed. However, both the mechanism res ponsible for their nucleation and a quantitative description of the st ress associated with such events have remained unresolved in the liter ature. In this paper, we first show that the nucleation of such cracks is consistent with the sliding of grain Facets along the column axes, and then describe a fracture mechanics-based model that correctly pre dicts their nucleation stress. (C) 1977 Acta Metallurgica Inc.