LABORATORY INDENTATION TESTS SIMULATING ICE-STRUCTURE INTERACTIONS USING CONE-SHAPED ICE SAMPLES AND STEEL PLATES

摘要

This paper describes the results of a series of tests from 2010-2012 in which cone-shaped ice samples were crushed into steel indenters. Previous work by the authors described the sample production techniques and testing procedures, this paper describes the cumulative results from all tests to date (in excess of 150) in which cone angle, indentation rate, ice type and temperature, and indenter roughness were varied. All ice-cone samples were right angled, circular pyramids with an opening angle varying between 100 and 180 degrees (flat-topped) projecting from a steel retaining ring 259 mm in diameter. Indentation rate was constant for individual tests and rates between 0.01 mm/s -100 mm/s were examined along with a series of collision tests involving closing speeds over 1500m/s. Ice was produced using distilled and chilled water, un-seeded and seeded with ice seeds ranging in size from snow particles to 3cm cubes, frozen at various rates and tested at temperatures between 0 and -30 degrees Celsius. Additionally, saltwater was frozen and tested as was natural iceberg ice harvested and placed in the steel retaining ring for testing. The indenter surface remained flat and perpendicular for all tests; however, three values of surface roughness (0.13, 0.47 and 500 micrometers) were examined over a range of indentation speeds. All data have been reduced to instantaneous force and crushing energy as a function of cone penetration and nominal volume. Trends are determined indicating the nature of load sensitivity to the control parameters. The transition from ductile to brittle behaviour is identified and mechanical processes are discussed.