Finite ice failure depth in penetration of a vertical indentor into an ice edge

This paper presents a partial analysis of data from an extensive series of laboratory indentation tests. The tests were conducted using flat indentors pushing against sheets of fresh-water ice of thickness 65 to 115 mm. The aspect ratio ranged from 0.9 to 2.6 with indentor velocities of 10 to 80 mm s−1. Details of an ice failure mode known as “crushing with flaking” are studied by making use of measured force-displacement signals and high-speed photography. With these test conditions, ice failure is associated with a production of symmetrical flakes which emanate simultaneously up and down. The failure begins in the middle level of the ice sheet as a rapid expansion of the ice. The post-peak phase of the ice failure involves loss ol the ice material over the whole contact area. The amount of ice that is extruded after the occurrence of the peak force is characterized by a finite failure depth parameter. According to present data, this failure depth is around 70% of the total depth of crushing and flaking that occur during a cycle of loading and unloading