THE COLLISION OF CONE SHAPE ICE SAMPLES AGAINST STEEL PLATES OF VARYING SURFACE ROUGHNESS

摘要

This paper describes experiments simulating ship collisions with ice, which have been conducted in the laboratory. Polycrystalline, anisotropic ice samples of 259 mm in diameter, at the steel ring/base, were shaped into 30° right angle cones. These cones were driven 40 mm or more into rigid, flat plates of varying roughness. Loads, displacements, spalling quantities and high speed video were recorded for all interactions which were conducted at closing speeds between 0.01 and 100 mm/s at a temperature of-10 °C. Three circular stainless steel plates were constructed using different contact surface finishes. The smoothest plate was polished to an average roughness (R_a) of 0.13 μm. The sanded medium plate has a roughness of 0.47 μm and the machined rough plate has a surface roughness of 500 μm. Peak force and cumulative crushing energy were determined at discrete penetrations and plotted against penetration rate and surface roughness. The results indicate that surface roughness influences peak force and crushing energy, though trends vary according to the interaction rate. At low interaction rates, 0.1 mm/s and below, the polished smooth plate gave rise to higher loads than the sanded medium plate. However, at indentation rates of 10 mm/s and above, forces on the medium plate were higher than on the smooth plate. Overall, use of the rough plate resulted in higher forces than both the sanded medium and the polished smooth plate. The data also shows the transition between ductile and brittle behaviour. A discussion of the possible mechanisms giving rise to these results is presented.