STRESS-SEPARATION CURVES FOR SALINE ICE USING FICTITIOUS CRACK MODEL

Linear elastic fracture mechanics (LEFM) is of limited use in analyzin g fracture tests conducted on laboratory-sized specimens of sea ice or saline ice. To extrapolate the results obtained from laboratory exper iments to larger sizes, nonlinear fracture mechanics must be invoked. The use of linear elastic fracture mechanics in the case of laboratory -sized specimens is invalidated-in general-by active near crack tip de formation mechanisms such as microcracking, grain boundary sliding, an d plastic slip. The fictitious crack model, which makes use of the str ess-separation curve, can be used to incorporate this process zone int o the fracture analysis so that fracture results from laboratory-sized specimens can be meaningfully interpreted. The stress-separation curv e for any type of ice has not yet been determined. In this paper, stre ss-separation curves for saline ice are constructed such that the resp onse computed using the fictitious crack model matches the experimenta l results. Crack plane orientations both parallel and perpendicular to the direction of the growth of the columnar grains are considered. Tw o different stress-separation curves are needed to model the crack gro wth in these two orientations. The fictitious crack model is implement ed using the weight function method. Various physical parameters that affect the obtained stress-separation curve are discussed.