This paper provides the results of two small-scale testing programs linked to large-scale field programs carried out by the writers and others. The large-scale in-situ sea ice testing program was part of the Office of Naval Research's (ONR's) Sea ice Mechanics Initiative (SIMI). Three field trips to Barrow, Alaska, were completed to examine the seasonal evolution of the first-year sea ice growing on Elson Lagoon. Trips were made in November, March, and May, when significant changes in thickness and temperature profile were evident. The experiments were designed to determine the fracture behavior of sea ice in situ and make comparisons with small-scale lab tests. Due to the unique microstructure of the sea ice tested, it was necessary to complete small-scale (0.1 m) tests for comparative purposes. A detailed study of the ice fabric at the site revealed a very strong alignment of the c-axis. This prompted a study of the fracture properties parallel (hard-fail) and perpendicular (easy-fail) to the preferred c-axes orientation plane. in both the large- and small-scale tests. The effects of c-axis alignment, temperature and microstructure on the fracture toughness and tensile strength are investigated.
